Macadamia nut processing method based on endogenous component transformation

Abstract

This invention relates to the field of food processing technology, and particularly to a macadamia nut processing method based on the transformation of endogenous components. The method includes the following steps: pre-fermenting raw macadamia nuts in their shells; regulating the microenvironment within the shells of the fermented nuts, followed by shell extraction and targeted enzymatic hydrolysis using an enzyme solution containing tanninase and β-glucosidase; preparing an endogenous concentrate using the enzyme solution, and adding high-melting-point triglyceride components and amino acids isolated from macadamia nut oil to form a eutectic induction solution; immersing the nuts in the eutectic induction solution and applying an asymmetric bidirectional pulsed electric field for assisted impregnation; subjecting the electric field-treated nuts to multi-stage controlled temperature-humidity-vacuum synergistic ripening and roasting; and surface seasoning, rapid cooling, and packaging the roasted nuts. These improvements guide the directional and beneficial transformation of the natural components within the nuts during processing.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, and in particular to a method for processing macadamia nuts based on the transformation of endogenous components. Background Technology

[0002] The core objective of macadamia nut processing is to achieve a crisp texture and roasted aroma while slowing down oxidation. Macadamia nuts are rich in endogenous substances with potential health benefits (such as polyphenols and gamma-tocopherol), which are largely lost during traditional high-temperature roasting. Furthermore, the complex interactions between these degradation products and the high oil content within the kernel can become a hidden key factor accelerating quality deterioration, limiting the potential for superior taste, and hindering the enhancement of health value. Specifically, macadamia nut skins and kernels contain bound polyphenols and other substances. In traditional processes, these are either washed away during pretreatment or destroyed at high temperatures, failing to be effectively utilized. Some degradation products may even become precursors to oxidation; the composition of macadamia nut oils determines their solid-state properties at room temperature; and traditional processing neglects their crystal morphology (such as crystal form, crystal size, and distribution). Large, unstable β' or β-type crystals are the microscopic cause of a "hard" rather than "crisp" texture and a gradual "gritty" texture during storage; "pursuing flavor (high-temperature Maillard reaction)" and "preserving nutrients (avoiding heat damage)" are contradictory in traditional processes; existing technologies can only weigh the pros and cons, not coordinate them. Summary of the Invention

[0003] The technical problem to be solved by this invention is to overcome the fundamental technical bottleneck that existing macadamia nut processing technology cannot simultaneously achieve the triple goals of "ultimate crispness", "exceptional oxidative stability" and "efficient retention of endogenous healthy components", and lacks regulation of the negative transformation of endogenous substances and the deterioration of oil crystallization during processing.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0005] The macadamia nut processing method based on endogenous component transformation includes the following steps:

[0006] S1: Pre-ferment the raw macadamia nuts in their shells;

[0007] S2: After fermentation, the microenvironment inside the shell of the fruit is regulated, and then the shell is broken to remove the kernel and targeted enzymatic hydrolysis is performed. The targeted enzymatic hydrolysis uses an enzyme solution containing tanninase and β-glucosidase.

[0008] S3: Use the enzyme treatment solution of S2 to prepare an endogenous concentrate, and add high-melting-point triglyceride components and amino acids separated from macadamia nut oil to form a eutectic induction solution;

[0009] S4: Immerse the kernels treated in S2 into the eutectic induction solution and apply an asymmetric bidirectional pulsed electric field for auxiliary impregnation;

[0010] S5: The nuts treated with the electric field undergo multi-stage temperature-humidity-vacuum co-ripening and roasting;

[0011] S6: Season the roasted nuts, quench them, and package them.

[0012] Furthermore, in the above-mentioned macadamia nut processing method based on the transformation of endogenous components, in S1, the pre-fermentation treatment uses a symbiotic fermentation agent of Lactobacillus plantarum and Saccharomyces cerevisiae, and the fermentation is carried out in a solution containing 2%~5% fructooligosaccharides at a temperature of 32℃~37℃ for 18~36 hours.

[0013] Furthermore, in the above-mentioned macadamia nut processing method based on endogenous component transformation, in S2, the microenvironment control within the shell is as follows: using an ozone-argon mixed gas with an ozone concentration of 10-30 ppm, treating the shelled nut at a pressure of 0.15-0.25 MPa for 15-30 minutes; in the targeted enzymatic hydrolysis treatment, the dosage of tanninase is 5-20 U / kg kernel, the dosage of β-glucosidase is 10-30 U / kg kernel, the treatment temperature is 35℃-40℃, and the time is 20-40 minutes.

[0014] Furthermore, in the above-mentioned macadamia nut processing method based on endogenous component transformation, in S3, the high-melting-point triglyceride component is a component rich in PPP and POP type triglycerides separated from the same batch of macadamia nut cold-pressed oil, and its addition amount is 3%~8% of the concentrated liquid solids; the amino acid is L-arginine, and its addition amount is 0.05%~0.2% of the kernel mass.

[0015] Furthermore, in the above-mentioned macadamia nut processing method based on endogenous component transformation, in S4, the parameters of the asymmetric bidirectional pulsed electric field are: positive pulse intensity 15~25 kV / cm, pulse width 10~20 μs; negative pulse intensity 3~8 kV / cm, pulse width 50~100 μs; frequency 100~200 Hz; processing time 5~15 minutes; and processing temperature below 30℃.

[0016] Furthermore, in the above-mentioned macadamia nut processing method based on the transformation of endogenous components, S5 specifically includes:

[0017] S51: Molecular cross-linking and maturation stage: Maintain at 45℃~55℃, relative humidity 75%~85%, and slight negative pressure -0.02 ~ -0.05 MPa for 1~2 hours;

[0018] S52: Gradient dehydration and non-enzymatic browning stage: Procedurally reduce humidity to 30%, raise temperature to 80℃~95℃, increase vacuum to -0.06 ~ -0.08 MPa, and maintain for 1~1.5 hours;

[0019] S53: Low-temperature vacuum precision baking and crystallization stage: Baking for 20~40 minutes at 105℃~118℃, vacuum degree ≤-0.08 MPa, and humidity <10%.

[0020] Furthermore, in the above-mentioned macadamia nut processing method based on the transformation of endogenous components, in S6, the quenching is to reduce the core temperature of the kernel to below 10°C within 3 minutes through a low-temperature, high-wind-speed environment of -5°C to 0°C.

[0021] The beneficial effects of this invention are: developing a macadamia nut processing method based on the transformation of endogenous components, guiding the natural components inside the kernel to undergo directional and beneficial transformation during processing, and using physical fields to precisely control oil crystallization, ultimately achieving a simultaneous leapfrog improvement in taste, oxidative stability and endogenous nutrient retention rate.

[0022] The remarkable effects of this invention stem from the synergistic effect of "endogenous component transformation - molecular orientation - eutectic network construction" resulting from the interconnected and deeply coupled steps described above:

[0023] The synergy between "shell-in-shell fermentation" and "targeted enzymatic hydrolysis": Shell-in-shell pre-fermentation creates a unique microenvironment and flavor precursors, laying the foundation for subsequent enzymatic transformation. The combination of tanninase and β-glucosidase precisely "activates" previously ineffective bound polyphenols into highly active free states, which not only preserves the components but also upgrades their activity. This step provides a crucial basis for the entire process of highly active endogenous antioxidants.

[0024] The synergy between "endogenous concentrate" and "asymmetric pulsed electric field" concentrates and reuses enzymatic hydrolysis products, achieving closed-loop, high-efficiency utilization of endogenous components. Adding high-melting-point triglycerides extracted from the product's own oils as "homogeneous seed crystals" is crucial for guiding ideal crystallization. The application of the asymmetric pulsed electric field is the finishing touch; it's not a simple mixing process, but rather uses physical field forces to drive the directional alignment and pre-assembly of polyphenols, amino acids, phospholipids, oils, and "homogeneous seed crystals," forming a highly ordered "precursor" at the microscopic scale. This pre-assembled structure is a prerequisite for the subsequent formation of an ideal eutectic network, an effect that cannot be achieved by any conventional stirring or settling process.

[0025] The synergy between the "phenol-amine cross-linking reaction" and "vacuum-controlled temperature co-crystallization": In the first stage of S5, the addition of L-arginine and mild conditions promote the phenol-amine cross-linking of free polyphenols and amino acids, resulting in a novel complex with significantly enhanced antioxidant activity, and its molecular structure is more easily embedded in the oil crystal network. In the third stage, under low-temperature vacuum baking, with pre-introduced "homogeneous seed crystals" as the core, and under the regulation of the phenol-amine complex network, the oil forms a large number of small, uniform, and stable β'-type crystals. This structure, where the "complex network encapsulates the small crystals," macroscopically exhibits extreme crispness (small, easily broken crystals) and a crumbly texture (the network provides support), while microscopically achieving physical confinement and chemical protection of the oil (the antioxidant effect of the phenol-amine complex), thus resolving the contradiction between taste and oxidation. Attached Figure Description

[0026] Figure 1 This invention relates to a flowchart of a macadamia nut processing method based on the transformation of endogenous components. Detailed Implementation

[0027] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments.

[0028] Example 1

[0029] The macadamia nut processing method based on the transformation of endogenous components includes the following sequential steps:

[0030] S1: Select 2 kg of shelled macadamia nuts, wash them, and immerse them in 4 L of aqueous solution containing 3% fructooligosaccharides. Inoculate with a starter culture of Lactobacillus plantarum:Saccharomyces cerevisiae = 1:2 (total viable count 10^8 CFU / mL); anaerobic fermentation at 35℃ for 24 hours.

[0031] S2: After fermentation, drain the water and introduce a mixture of 20 ppm ozone (argon balanced) gas at 0.2 MPa for 20 minutes; break the shells and extract the kernels (about 1 kg of kernels); immediately immerse the kernels in 2L of citric acid-malic acid buffer solution at pH 5.0 and 40℃, add tanninase (10 U / kg kernels) and β-glucosidase (20 U / kg kernels), and gently stir at 35℃ for 30 minutes;

[0032] S3: Collect the enzymatic hydrolysate, microfilter, and concentrate under vacuum at 50℃ to 400mL. Add 6g of the high-melting-point fraction (mainly PPP / POP) isolated from the same batch of nut oil and 0.8g of L-arginine, and homogenize.

[0033] S4: Immerse the kernels in the concentrated solution and treat them with an electric field (positive 20kV / cm / 15μs, negative 5kV / cm / 80μs, frequency 150Hz) for 10 minutes at a temperature <30℃.

[0034] S5: Multi-stage temperature-humidity-vacuum controlled synergistic maturation and baking:

[0035] Phase 1: 50℃, 80% humidity, -0.03 MPa, maintain for 1.5 hours;

[0036] Phase Two: Humidity is reduced from 80% to 30%, temperature is increased to 90℃, and vacuum is increased to -0.07 MPa, maintained for 1 hour;

[0037] Stage 3: 112℃, -0.085 MPa, <10% humidity, bake for 30 minutes;

[0038] S6: Spray with a trace amount of sea salt and natural vanillin mist, immediately enter the -2℃ cooling tunnel for 3 minutes for rapid cooling, and then pack with nitrogen.

[0039] Example 2

[0040] The macadamia nut processing method based on endogenous component transformation described in Example 1 differs in the following ways: In S1, a fermentation agent of *Lactobacillus plantarum* and *Saccharomyces cerevisiae* in a 1:1 ratio is inoculated; in S2, the ozone concentration is 15 ppm, the pressure is 0.18 MPa, and the time is 25 minutes; the enzyme dosage is 15 U / kg for tanninase and 25 U / kg for β-glucosidase, and the time is 40 minutes; in S4, the electric field parameters are: positive 22 kV / cm / 12 μs, negative 6 kV / cm / 90 μs, frequency 180 Hz, and the time is 8 minutes; in S5, stage one is 48℃, 85% humidity, -0.04 MPa, and the time is 2 hours; stage three is 115℃, -0.09 MPa, and the time is 25 minutes for roasting.

[0041] Comparative Example 1

[0042] The macadamia nut processing method uses traditional techniques, where the kernels are directly roasted in hot air at 135℃ for 35 minutes.

[0043] Comparative Example 2

[0044] The macadamia nut processing method in Example 1 differs in that steps S1, S2, and S6 are performed, while steps S3-S5, including electric field, eutectic induction, and three-control ripening roasting, are omitted, and the nut is directly roasted according to the conditions of Comparative Example 1.

[0045] Comparative Example 3

[0046] In the processing method of macadamia nuts, the difference in Example 1 is that S1-S3 and S5-S6 are performed, but S4 is changed to conventional static soaking for 1 hour.

[0047] Comparative Example 4

[0048] The macadamia nut processing method, in Example 1, differs in that S1-S6 are performed, but in S3, the high-melting-point triglyceride component extracted from its own oil is not added.

[0049] Comparative Example 5

[0050] The macadamia nut processing method, in Example 1, differs in that S1-S6 are performed, but L-arginine is not added in S3, and in S5 the humidity is reduced to 60% to inhibit the reaction.

[0051] Comparative Example 6

[0052] In the processing method of macadamia nuts, the difference in Example 1 is that S2-S6 are performed, and S1 is omitted.

[0053] Comparative Example 7

[0054] The macadamia nut processing method, in Example 1, differs in that after the pre-fermentation with the shell in S1, the ozone-argon mixed gas treatment in S2 is not performed, and the shell is directly broken by enzymatic hydrolysis; S3-S6 are then performed.

[0055] Comparative Example 8

[0056] The macadamia nut processing method in Example 1 differs in that ozone treatment is absent in S1-S6 and S2, but Bacillus subtilis protease (a conventional alkaline protease) (2 g / L) is used in the enzymatic hydrolysate instead of tanninase and β-glucosidase.

[0057] Comparative Example 9

[0058] In the processing method of macadamia nuts, the difference in Example 1 is that the complete S1-S3 and S5-S7 are performed, but the electric field parameters of S4 are changed to symmetrical pulses (both positive and negative are 15kV / cm, pulse width is 30μs, and frequency is 100Hz).

[0059] Comparative Example 10

[0060] The macadamia nut processing method in Example 1 differs in that S1-S6 are performed, but S5 is replaced by a three-stage temperature and humidity controlled baking at atmospheric pressure (parameters are the same as in Example 1 but without vacuum).

[0061] Comparative Example 11

[0062] The macadamia nut processing method in Example 1 differs in that S1-S5 are performed completely, while S6 is performed by slow cooling at room temperature (30 minutes to room temperature).

[0063] Comparative Example 12

[0064] The macadamia nut processing method in Example 1 differs from the conventional process (Comparative Example 1) in that 0.02% TBHQ (tert-butylhydroquinone) is added before roasting.

[0065] Experimental Example 1

[0066] 1.1 Analysis of endogenous components:

[0067] Macadamia nuts from each experimental group (examples and comparative examples) were immediately flash-frozen in liquid nitrogen after processing, and then ground into a uniform fine powder with a particle size of less than 60 mesh. The grinding process was kept at a low temperature to avoid changes in composition.

[0068] The powder sample was placed in an ultra-low temperature freezer at -80℃ or in a nitrogen-filled, light-proof container until analysis.

[0069] Extraction of free polyphenols:

[0070] Accurately weigh 1.00 g of sample powder (accurate to 0.0001 g) and place it in a 50 mL centrifuge tube.

[0071] Add 20 mL of acidified methanol / water solution (methanol:water:hydrochloric acid = 80:20:1, v / v / v).

[0072] Ultrasonic extraction was performed at room temperature for 30 minutes (power 250W, frequency 40kHz), followed by centrifugation at 4℃ and 8000 rpm for 15 minutes.

[0073] Collect the supernatant. Extract the residue once more, and combine the two supernatants.

[0074] The combined supernatant was concentrated to near dryness using a rotary evaporator at 40°C, redissolved in 2 mL of methanol (chromatographic grade), and filtered through a 0.22 μm organic microporous membrane for HPLC analysis. This fraction is the free polyphenol extract.

[0075] Extraction of bound polyphenols (acid decomposition release):

[0076] Add the residue after the above free extraction to 20 mL of a solution containing 2 M NaOH (purged with nitrogen to remove oxygen).

[0077] Hydrolysis was carried out at room temperature under nitrogen protection with magnetic stirring for 2 hours.

[0078] Carefully adjust the pH of the mixture to 2.0 using 6 M HCl.

[0079] Add 20 mL of ethyl acetate and vortex extract. Repeat the extraction three times and combine the ethyl acetate layers.

[0080] The ethyl acetate phase was rotary evaporated to dryness at 40 °C, reconstituted with 2 mL of methanol, filtered through a 0.22 μm filter membrane, and then analyzed by HPLC. This portion is the extract of bound polyphenols (released by alkaline decomposition).

[0081] High performance liquid chromatography (HPLC) analysis of ellagic acid content

[0082] Instrument: Agilent 1260 Infinity II HPLC-DAD system, equipped with a Zorbax Eclipse Plus C18 column (4.6 × 250 mm, 5 μm).

[0083] Mobile phase:

[0084] Phase A: 0.1% formic acid aqueous solution

[0085] Phase B: 0.1% formic acid acetonitrile solution

[0086] Gradient elution procedure: see Table 1;

[0087] Table 1

[0088]

[0089] Flow rate: 1.0 mL / min

[0090] Column temperature: 30℃

[0091] Detection wavelength: 260 nm (maximum absorption wavelength of ellagic acid)

[0092] Injection volume: 10 μL

[0093] Quantitative method: External standard method. Prepare a series of ellagic acid standard solutions of various concentrations (e.g., 0.5, 1, 5, 10, 20, 50 μg / mL) and plot a standard curve (usually y = ax + b, R²>0.999). Calculate the content based on the peak area of ​​the sample.

[0094] calculate:

[0095] Free ellagic acid content (mg / 100g) = (C_free×V×N ×100) / (W×1000)

[0096] Bound ellagic acid content (mg / 100g) = (C_bound×V×N×100) / (W×1000)

[0097] Total ellagic acid content = free state + bound state

[0098] Free ellagic acid retention rate (%) = (Free ellagic acid content in finished product / Total ellagic acid content in raw kernels) × 100%

[0099] Where: C is the concentration measured by HPLC (μg / mL), V is the volume of the reconstituted solution (mL), N is the dilution factor, and W is the sample mass (g).

[0100] Determination of total phenol content (Folin-Ciocalteu method)

[0101] Principle: Polyphenols reduce phosphomolybdic acid (Folin reagent) under alkaline conditions to produce a blue compound with maximum absorption at 765 nm.

[0102] step:

[0103] Take 0.1 mL of appropriately diluted total phenol extract (extract with 70% acetone, similar to the free state, but without acidification).

[0104] Add 0.5 mL of Folin-Ciocalteu reagent (pre-diluted 10 times with deionized water), mix well, and react at room temperature for 5 minutes.

[0105] Add 1.5 mL of 7.5% (w / v) sodium carbonate solution and mix well.

[0106] After being placed in the dark for 60 minutes, the absorbance was measured at a wavelength of 765 nm.

[0107] Standard curve: prepared using gallic acid standard (0-200 μg / mL).

[0108] Calculation: Total phenol content is expressed as gallic acid equivalent (mg GAE / 100g sample).

[0109] 1.2 Microstructure (Oil Crystallization Morphology) Analysis

[0110] Take a whole macadamia nut and quickly slice off a thin slice approximately 3mm × 3mm × 1mm (thickness) using a sharp blade on a low-temperature work surface (4°C). The cut should go through the center of the nut to observe the cross-section.

[0111] Place the slices immediately on a pre-cooled glass slide (the slide was previously stored at 4°C).

[0112] Quickly place a pre-cooled coverslip on top, gently press it down to avoid creating air bubbles.

[0113] Immediately transfer the prepared slide to the microscope stage for analysis. The entire process should be completed within 2 minutes and should be carried out at a low temperature as much as possible to prevent the crystal from melting or undergoing a crystal transformation due to increased temperature.

[0114] Polarized light microscopes equipped with a cooled stage and digital imaging system (such as the Olympus BX53-P).

[0115] Objective lens: 20x or 40x oil immersion objective lens (to obtain sufficient resolution for observing micron-sized crystals);

[0116] Polarizer: The polarizer and analyzer are orthogonal (to obtain the clearest image of crystal birefringence).

[0117] Stage temperature: precisely controlled at 20±0.5℃ (simulating room temperature storage conditions), using a Peltier temperature control system;

[0118] At least five different fields of view were randomly selected for each sample to ensure that the images were clear and had good contrast.

[0119] Crystal morphology scoring criteria (1-10 points): see Table 2;

[0120] Table 2

[0121]

[0122] The scores were independently rated by at least two trained observers, and the average score was taken.

[0123] The crystal size is quantified using digital image analysis software (such as Image-Pro Plus, ImageJ); the color PLM image is converted into an 8-bit grayscale image, and threshold segmentation is performed to distinguish the crystal from the background; the software automatically identifies each crystal particle.

[0124] Calculate the average value of its area-equivalent diameter or Feret diameter.

[0125] Count the number of crystals in each size range and plot a distribution histogram. The examples should show a narrow and concentrated distribution (e.g., mainly distributed in 5-12 μm), while the comparative examples have a wider distribution.

[0126] Crystal roundness is calculated using the formula: Roundness = 4π × Area / Perimeter². An ideal sphere is rounded to 1, while needle-like or rod-shaped crystals are rounded to less than 1. This formula can be used to aid in determining crystal morphology. The final data for each sample is the average ± standard deviation of measurements taken from at least 5 fields of view and a total of no less than 200 crystal particles.

[0127] The results of the analysis of endogenous components and microstructure are shown in Table 3.

[0128] Table 3

[0129]

[0130] The endogenous component data from Table 3 show that:

[0131] The free ellagic acid in Examples 1 and 2 (156.8 & 148.6 mg / 100g) reached more than 12 times the content in raw kernels, proving that the three-step tandem process of "pre-fermentation with shell (S1)" → "ozone-argon regulation (first half of S2)" → "targeted enzymatic hydrolysis (second half of S2)" achieved an unprecedentedly successful conversion effect.

[0132] S1 (fermentation): Microbial metabolism produces organic acids and a mild reducing environment, which activates the endogenous enzyme system of the kernel and may partially hydrolyze the matrix encapsulating polyphenols.

[0133] S2 first half (ozone regulation): Short-term, low-pressure oxidative stress further damages the integrity of the cell wall and may oxidize some polyphenols into quinone intermediates that are more easily acted on by enzymes.

[0134] S2 second half (targeted enzymatic hydrolysis): Tanninase specifically hydrolyzes the ester bond of ellagic acid, and β-glucosidase hydrolyzes the glycosidic bond of polyphenols. The two work together to "shear" the bound polyphenols and release them into free ellagic acid.

[0135] Bound ellagic acid (42.1 & 45.3 mg / 100g): significantly reduced to about 23% of that in raw kernels, which corroborates the data of the free form and intuitively demonstrates the conversion efficiency.

[0136] Comparative Example 2 (fermentation and enzymatic hydrolysis only): Limitations of basic transformation;

[0137] Free ellagic acid (125.3 mg / 100g): significantly lower than in Example 1 (-20%). Although the core role of enzymatic hydrolysis was retained, the electric field induction (S4) and co-crystallization ripening roasting (S5) were missing. This indicates that even if polyphenols are converted, without subsequent "electric field-induced molecular orientation" and "phenol-amine cross-linking fixation", some free polyphenols may be lost, degraded, or undergo ineffective polymerization during subsequent water washing, draining, or conventional high-temperature roasting.

[0138] Comparative Example 6 (without pre-fermentation with shell): Loss of the conversion "starter";

[0139] Free ellagic acid (98.5 mg / 100g): only 63% of that in Example 1. The absence of S1 resulted in insufficient "start-up" of the entire conversion process. Direct enzymatic hydrolysis without the mild biochemical pretreatment of fermentation resulted in cell walls and contents that were closer to the raw material, reducing the "responsiveness" to subsequent ozone and enzymatic treatments. The lack of flavor precursors and a slightly acidic environment from fermentation significantly reduced the efficiency of the entire conversion system. This data directly demonstrates that "pre-fermentation in the shell" is not an optional step, but rather provides a crucial start-up signal and microenvironment preparation for the entire endogenous component conversion chain.

[0140] Comparative Example 7 (without ozone-argon regulation): loss of conversion "activator";

[0141] Free ellagic acid (108.6 mg / 100g): lower than Comparative Example 6, but higher than Comparative Example 8. This indicates that the ozone-argon regulation plays a unique and crucial role. The mild oxidizing effect of ozone can specifically alter the microstructure of the kernel surface and the state of polyphenols, making them more accessible and actionable by enzymes. The inert atmosphere of argon prevents over-oxidation. Without this step, enzymatic hydrolysis can only act on "unactivated" substrates, limiting efficiency. Comparing Comparative Examples 6 and 7: the data are similar but different, indicating that S1 (fermentation) and the first half of S2 (ozone regulation) are two different but equally important pretreatments that work together to create optimal conditions for enzymatic hydrolysis.

[0142] Comparative Example 8 (non-targeted enzymatic hydrolysis): loss of the "precise tool" for transformation;

[0143] Free ellagic acid (35.6 mg / 100g): A precipitous drop, only 23% of that in Example 1, is one of the most compelling data points. Conventional alkaline proteases target proteins, not the ester or glycosidic bonds specific to polyphenols. They cannot achieve the specific conversion of bound polyphenols to free ellagic acid. This data strongly demonstrates that the specific combination of tanninase and β-glucosidase is an irreplaceable "molecular scissors" in this invention. Its "targeting" is the core technical characteristic of efficient conversion, unmatched by any conventional protease.

[0144] Comparative Example 3 (without electric field assistance) and Comparative Example 4 (without homologous seed crystals): The key link of composition "fixation and assembly" is lost;

[0145] The free ellagic acid content of both (141.5 mg / 100g, 143.2 mg / 100g) was not significantly different from that of Example 1, indicating that the conversion step itself was effective. However, their crystal sizes (15.4 μm, 18.9 μm) were significantly degraded (see microstructure interpretation below). This indicates that the main role of S3 (preparation of eutectic induction solution) and S4 (electric field assisted) was not to further improve the conversion rate, but to "molecularly assemble" and "pre-position" the converted active ingredients (free polyphenols, amino acids) with the oil components, preparing for the subsequent formation of an ideal micro-eutectic structure. Without them, although the conversion products exist, they cannot be effectively "woven" into the final product structure.

[0146] Comparative Example 5 (without phenol-amine crosslinking promotion): loss of network "stabilizer";

[0147] Free ellagic acid (138.7 mg / 100g): Retention was acceptable. However, combined with the significantly worsened oxidative stability data (POV increased by 77%), it indicates that the lack of L-arginine and the corresponding mild cross-linking conditions prevented the free polyphenols from forming a stable phenolic amine antioxidant network with proteins / amino acids. Although these polyphenols were present, they were in a "free, scattered" state, easily consumed by oxidation, and unable to provide long-lasting and stable protection. This demonstrates that "immobilized antioxidants" are superior to "free antioxidants".

[0148] From the microstructure (oil crystallization) data in Table 3, we can see that:

[0149] The average crystal size in Examples 1 and 2 (8.2 & 8.8 μm) reached an extremely small scale. Small crystals mean that they are more prone to uniform and dense fragmentation under stress, macroscopically manifesting as "brittle upon contact with the palate." Morphological scores (9.2 & 9.0): close to perfect, corresponding to "fine needle-like structures with extremely uniform distribution." This structure is the ultimate product of the synergistic effect of "homogeneous seed induction," "electric field pre-assembly," and "vacuum-controlled slow crystallization."

[0150] Homologous high-melting-point triglycerides (from S3): provide uniformly distributed crystallization nuclei that are fully compatible with the main oil, which is the basis for obtaining fine crystals.

[0151] Asymmetric pulsed electric field (S4): Its unique parameters (strong positive pulses penetrate the cell membrane, and weak negative pulses adjust the orientation of polar molecules) force polyphenols, amino acids, phospholipids and lipids to oriented around the crystal nucleus, forming a highly ordered "pre-crystallized complex".

[0152] Vacuum temperature-controlled baking (S5 stage 3): The vacuum environment lowers the boiling point of the oil, allowing dehydration and shaping to take place at a relatively low temperature (105-118℃). Low-temperature slow baking avoids damage to the pre-assembled structure caused by thermal disturbance, allowing the crystals to grow slowly and uniformly into fine β' types centered on a pre-set crystal nucleus.

[0153] Comparative Example 4 (without homologous seed crystals): Loss of crystallization "seed";

[0154] Crystal size (18.9 μm): 130% larger than in Example 1. Without a high-melting-point component extracted from the oil itself as a "homogeneous seed crystal," the crystallization process relied solely on randomly formed nuclei within the system, resulting in a small and uneven number of nuclei and thus coarse crystals. Conclusion: Exogenous additives cannot replace this "homogeneous seed crystal," which is completely identical to the host oil in chemical structure and crystallization habit. This is a prerequisite for achieving precise control of crystal size.

[0155] Comparative Example 3 (without electric field assistance): Loss of molecular "pre-assembly";

[0156] Crystal size (15.4 μm): 88% larger than in Example 1. Despite the presence of homologous seeds, the lack of asymmetric pulsed electric field driving the crystals prevented polyphenols, amino acids, and other molecules from being forcibly aligned at the oil-water interface and around the crystal nucleus. The crystallization process lacked pre-guided molecular structure, resulting in decreased orderliness, poorer crystal growth directionality, larger size, and reduced uniformity (standard deviation of 5.2 μm, also greater than the 1.5 μm in Example 1). Conclusion: Electric field treatment is not a simple mixing process, but rather a "precise positioning" step that imparts specific orientations and positions to molecules, significantly influencing the final crystal morphology.

[0157] Comparative Example 9 (Inappropriate Electric Field Parameters): Proof of Parameter Sensitivity;

[0158] Crystal size (13.8 μm): Using a symmetrical pulsed electric field, the effect falls between that with and without an electric field. This demonstrates that the design of asymmetric pulses (strong positive pulses for transmembrane transport, weak negative pulses for polarity adjustment) has specific physicochemical purposes, and not all electric fields can achieve the same effect. Symmetric pulses cannot achieve effective molecular sorting and orientation.

[0159] Comparative Example 10 (without vacuum baking): Loss of the crystal's "mild growth environment";

[0160] Crystal size (14.6 μm): Caused by high-temperature baking at ambient pressure.

[0161] The rapid evaporation of water generates internal stress, which destroys the already formed fine crystal nuclei.

[0162] High temperatures intensify molecular thermal motion, disrupting the ordered structure pre-assembled by the electric field.

[0163] The crystals coarsen rapidly at high temperatures (Ostwald ripening).

[0164] Conclusion: The vacuum environment is not only related to flavor preservation, but also provides an indispensable physical condition for the low-temperature, mild and controllable crystallization of oils and fats. It is a key process parameter for obtaining fine and stable crystals.

[0165] Comparative Example 11 (lacking rapid cooling): loss of structural "fixation";

[0166] Crystal size (11.3 μm): While better than most comparative examples, it is still 38% larger than Example 1. During slow cooling, the crystal has ample time to continue growing and transforming (from the metastable β' to the more stable β type), resulting in increased size and morphological changes. Conclusion: Rapid quenching (S6), like "quenching," instantly fixes the ideal submicron / micron-scale crystal structure formed at the end of baking, preventing further changes and acting as the "final step" to lock in the final texture.

[0167] Comparative Examples 1, 2, 5, 6, 7, 8, 12: Systematic deterioration of crystal structure;

[0168] These comparative samples generally had crystal sizes exceeding 20 μm and morphology scores below 6.5. The root causes are: they either lacked a transformation step (resulting in a lack of active polyphenols that can interact with oils), or they lacked an induction / assembly step, or they lacked an ideal crystallization environment. Their crystallization process degenerated into the traditional, uncontrolled, and extensive crystallization of macadamia nuts, naturally resulting in large, uneven crystals, corresponding to a mediocre or poor texture (hard, tough, gritty).

[0169] The results above show that the endogenous component data chain traced the entire process of transformation and fixation from bound polyphenols to free polyphenols, and then to stable antioxidant components immobilized in the phenol-amine network. Data fluctuations at each step precisely pinpointed the absence of specific process steps. The microstructure data chain, on the other hand, demonstrates the crystal engineering path from the introduction of homologous seed crystals to electric field-induced pre-assembly, and then to vacuum mild crystallization and rapid cooling for shaping. Differences in crystal size and morphology directly reflect the precision of control over this path.

[0170] Excellent free polyphenol content (highly active substances) must be combined with an excellent crystal structure (an ideal physical carrier) and integrated through phenol-amine crosslinking (stable chemical bonding) to produce an ultimate taste and exceptional stability. Example 1 perfectly embodies this synergistic concept, while the comparative data demonstrates from various perspectives that dismantling any link in this synergistic system will significantly diminish the overall effect.

[0171] Experiment Example 2

[0172] 2. Texture and physical property analysis:

[0173] 2.1 Specific methods for texture analysis (TPA);

[0174] This method uses a texture analyzer to perform two-point compression tests to simulate the early stage of human oral chewing in order to obtain objective and repeatable texture parameters.

[0175] Sampling: Randomly select at least 20 roasted macadamia nuts that are intact and have no visible cracks from each experimental group.

[0176] Pretreatment: The sample to be tested was placed in a constant temperature and humidity chamber and equilibrated for at least 24 hours at a temperature of 25±1℃ and a relative humidity of (50±5)% to unify its water activity and temperature and eliminate the influence of environmental fluctuations on texture.

[0177] Test surface selection: Lay each kernel flat, ensuring that its two flattest and largest surfaces contact the test probe. For irregularly shaped kernels, ensure that the contact surface is as consistent as possible for each test.

[0178] Instruments: Texture analyzer (such as Stable Micro Systems' TA.XT Plus, TA.HD Plus, etc.).

[0179] Probe: Cylindrical flat-bottomed probe, with a recommended diameter of 36 mm (P / 36R) or 75 mm (for larger samples). The 36 mm probe provides a moderate contact area, avoids sample edge effects, and is a common choice for testing nut samples.

[0180] Test mode: Compression-Return, performing compression twice.

[0181] Key parameter settings:

[0182] Pre-test speed: 2.0 mm / s (slow approach, accurate positioning).

[0183] Test speed: 1.0 mm / s (simulates a relatively slow chewing speed, which can better distinguish brittle characteristics).

[0184] Post-test speed: 10.0 mm / s (rapid return, preparing for the next test).

[0185] Strain: 70% (This is a key parameter for nut texture analysis. Compressing the sample to 70% of its original height is sufficient to cause the kernel to fully fracture, thus recording the complete brittle fracture process).

[0186] Trigger force: 5.0 g (data recording and deformation begin when the probe contacts the sample surface and reaches this force value).

[0187] Time between cycles: 2.0 seconds (simulating the interval between two chews).

[0188] Data acquisition rate: ≥200 points / second, to ensure that instantaneous brittle fracture signals can be captured.

[0189] Test steps:

[0190] Step 1: Instrument Calibration: Perform force and height calibration according to the manufacturer's guidelines.

[0191] Step 2: Place a well-balanced macadamia nut kernel precisely in the center of the platform.

[0192] Step 3: Start the test program in the software. The probe descends, contacts the sample, and after reaching the trigger force, compresses the sample to 70% of its original height at a speed of 1.0 mm / s, and then returns.

[0193] Step 4: After a 2-second interval, perform a second compression under the same conditions.

[0194] Repeat steps 2-4 until all 20 samples in the group have been tested.

[0195] Extract the following key parameters from the force-time or force-deformation curves exported by the software. Taking a typical nut TPA curve as an example, key feature points include:

[0196] Hardness (H): Defined as the maximum peak force (in g or N) achieved during the first compression cycle. It represents the maximum force required to cause the sample to fracture. The higher the value, the "harder" the sample.

[0197] Fracturability (F): In nut testing, it is typically defined as the force corresponding to the first significant peak value observed during the first compression cycle. If the sample is very brittle, this first peak value is often the maximum peak value (i.e., brittleness = hardness). For samples with a denser structure, the subsequent structure may still provide greater resistance after the first small fracture. Therefore, in this paper, to highlight the "brittleness" characteristic, we define brittleness directly as the maximum peak force during the first compression (i.e., the same as the hardness value, but emphasizing its role as an indicator of "brittleness" in texture).

[0198] Work of Fracture (W_f): Calculated as the area (in mJ) along the first compression curve from the start to the first major peak (or maximum peak). It represents the energy required to cause the sample to fracture initially. A smaller work of fracture indicates that the sample is easier to chew, resulting in a more "crispy" rather than "tough" texture.

[0199] Brittleness Index (BI): This is a comprehensive index used to evaluate brittleness more fully. The calculation formula can be defined as:

[0200] BI = (brittleness value F) / (fracture work W_f) or BI = (brittleness value F) / (deformation D_f at peak brittleness).

[0201] For a more intuitive understanding, this analysis uses the formula: BI = F / W_f. A higher ratio indicates that a unit of energy consumption can generate a greater breaking force, meaning the sample is more brittle, easier to break, and has a better texture.

[0202] Data processing: For each parameter of 20 replicate samples in each group, calculate its arithmetic mean and standard deviation. The magnitude of the standard deviation can reflect the uniformity of taste (e.g., the smaller the standard deviation of hardness or crispness, the smaller the texture difference between different kernels in the group, or even different parts of the same kernel).

[0203] 2.2 Specific methods for moisture absorption rate determination: Moisture absorption rate is a key physical indicator for measuring a product's ability to resist moisture absorption and maintain its crisp texture during storage.

[0204] Instruments and materials:

[0205] Temperature and humidity chamber: can precisely control the temperature at 25±0.5℃ and the relative humidity at 75±2%.

[0206] Analytical balance: accuracy 0.0001 g.

[0207] Dryer: Built-in saturated sodium chloride solution (creates a stable humidity environment of about 75% RH at 25°C, as a backup or for calibration).

[0208] Flat weighing bottles or petri dishes with lids.

[0209] Sample pretreatment (drying):

[0210] Grind the macadamia nuts to be tested into a uniform powder (passing through a 40-mesh sieve). Take an appropriate amount of powder (about 2-3g) and spread it evenly in a pre-weighed weighing bottle (W0), and weigh it accurately (W1). Place the weighing bottle in a forced-air drying oven and dry it at 105℃ until constant weight (for example, after drying for 3 hours, weigh it every hour, and the difference between two weighings should be less than 0.001g). After removing it, place it in a desiccator (filled with silica gel) to cool to room temperature, and weigh it immediately (W2). Calculate the initial dry basis moisture content: Initial moisture content (%) = [(W1 - W2) / (W2 - W0)] × 100%. Record the total weight of the sample and the weighing bottle at this point as the initial dry weight (W_dry).

[0211] Moisture absorption test:

[0212] Open the cap of the weighing bottle containing the dried sample and quickly place it in a constant temperature and humidity chamber stabilized at 25°C and 75% RH. Start timing. At the set time point (e.g., 48 hours), remove the weighing bottle and immediately cap it to prevent moisture absorption or loss during weighing. Weigh quickly using an analytical balance (W_t). Prepare at least three replicates for each experimental group.

[0213] Moisture Absorption Rate (MAR): The percentage of moisture absorbed within a specific time period, calculated on a dry basis.

[0214] MAR (%) = [(W_t - W_dry) / (W_dry - W0)] × 100%;

[0215] The results of the analysis of texture and physical properties are shown in Table 4:

[0216] Table 4

[0217]

[0218] As shown in Table 4, Example 1 achieved a perfect combination of "high brittleness (3100 g) - low fracture energy (8.5 mJ) - high brittleness index (0.85)" in terms of texture, while exhibiting "low moisture absorption (1.23%)" in terms of physical stability. This set of data directly reflects the macroscopic mechanical and physical properties of the "phenolamine-eutectic network" microstructure constructed in this invention. The data of all comparative examples deviate from this "golden combination," and the direction of deviation strictly corresponds to the process defects.

[0219] Example 1 and Example 2

[0220] High brittleness (3100 & 2980 g): This is not simply "hardness," but rather the maximum fracture force during the first compression. A high value indicates strong structural rigidity of the sample, but the key lies in its combination with low fracture energy.

[0221] Low fracture energy (8.5 & 8.9 mJ): This means that only a very small amount of energy is needed for its structure to collapse. The coexistence of high brittleness and low fracture energy is the scientific definition of "crisp": it breaks easily with a bite (high brittleness) and requires little effort (low energy consumption).

[0222] High brittleness index (0.85 & 0.80): This is the ratio of the two indicators mentioned above, quantifying the "brittleness efficiency". The BI value (0.85) of Example 1 far exceeds that of all comparative examples, making it a comprehensive indicator of the success of the synergistic system.

[0223] Mechanism correlation:

[0224] Fine, uniform β'-type crystals (average 8.2 μm) form dense, uniform weak points throughout the kernel. Under pressure, stress is highly concentrated at these weak points, rapidly triggering a chain reaction of fractures, resulting in high brittleness. The phenolic amine cross-linked network, like "reinforcing steel in concrete," provides integrity but does not absorb a large amount of energy during crystal fracture (non-tough protein network), while preventing energy dissipation during fracture (such as plastic deformation), thus achieving low fragmentation work. Electric field-induced molecular pre-assembly ensures the uniformity of the aforementioned crystal and network structures, resulting in highly repeatable force-deformation curves for each engagement (compression test), exhibiting low standard deviation.

[0225] Comparative Example 3 (without electric field assistance): Molecular disorder leads to loose structure

[0226] Decreased brittleness (2700 vs 3100 g, -13%): Without the driving force of an asymmetric pulsed electric field, polyphenols, amino acids, etc., failed to effectively orient themselves on the lipid crystals and interfaces. This resulted in a low degree of order and weakened structural strength in the formed "phenol-amine eutectic network," which macroscopically manifested as a decrease in the peak force resisting fracture.

[0227] Increased fracture energy (9.8 vs 8.5 mJ, +15%): A loose structure means that the fracture process may not be clean and crisp. Fracture may begin at a weak point, but more energy is needed to overcome the resistance from the subsequent irregular structure, or some minor plastic deformation may occur, thus increasing the total energy consumption.

[0228] The brittleness index decreased (0.70 vs 0.85): This is a result of both decreased brittleness and increased fragmentation energy, indicating a significant reduction in fracture efficiency.

[0229] Conclusion: The electric field treatment (S4) is not a dispensable "hybrid" step, but a key directional assembly process that endows the final structure with high strength and high brittle fracture efficiency.

[0230] Comparative Example 4 (without homologous seed crystals): Coarse crystals result in "hardness and difficulty in breaking".

[0231] Decreased brittleness (2550 vs 3100 g, -18%): The coarse and inhomogeneous crystals (18.9 μm) result in fewer and less uniform stress concentration points. Under stress, the stress needs to accumulate to a higher level before it can trigger the fracture of a few large crystals, and the fracture may not be instantaneous and penetrate the entire structure. Therefore, the first measured maximum peak force is actually lower.

[0232] The fracture energy was significantly increased (10.5 vs 8.5 mJ, +24%): the fracture of coarse crystals itself requires more energy. More importantly, the bonding regions between crystals (composed of phenolic amine networks) may become thinner or uneven in thickness due to irregular crystal interfaces, resulting in more friction, slippage, and localized plastic deformation during fracture, which greatly increases energy consumption.

[0233] Increased moisture absorption (2.12% vs 1.23%): Coarse crystals result in large and irregular microstructure pores, providing more space and channels for water molecule adsorption and capillary condensation.

[0234] Conclusion: Homologous high-melting-point seed crystals (S3) are the cornerstone for obtaining fine and uniform crystals. Without them, all subsequent optimizations are impossible, and the product will revert to a mediocre state of being "hard, tough, and easily hygroscopic".

[0235] Comparative Example 5 (without phenolic crosslinking promotion): Loss of network strengthening and stabilization

[0236] The brittleness is well maintained (2900 g): because the crystal structure itself (fine needle-like, 12.5 μm) still benefits from the effect of the seed crystal and the electric field.

[0237] However, the moisture absorption rate deteriorated significantly (1.65% vs 1.23%, +34%): This is the most critical signal. The lack of L-arginine prevented the formation of a sufficient phenolic amine cross-linking network, resulting in weak interfacial bonding between crystals and the presence of microscopic defects. A large number of molecules with hydrophilic groups (hydroxyl, amino) failed to be "fixed" in the hydrophobic network through cross-linking and were instead exposed, easily adsorbing water molecules.

[0238] This set of data perfectly explains the dual role of the "phenolic amine network": firstly, it enhances the texture (contributing to brittleness), and secondly, it acts as a hydrophobic barrier (determining hygroscopicity). Comparative Example 5 has a acceptable texture but poor stability, indicating that the mild cross-linking conditions in stage one of S5 mainly contribute to long-term stability, and are key to "preserving brittleness" rather than "increasing brittleness."

[0239] Comparative Example 9 (Inappropriate Electric Field Parameters): The Necessity of Asymmetric Design

[0240] The various indicators fall between those with no electric field and those with an optimal electric field: the effect of using a symmetrical pulse (Comparative Example 9) is better than that of no electric field (Comparative Example 3), but significantly worse than that of an asymmetrical pulse (Example 1). This proves that:

[0241] The electric field itself plays a role (potentially promoting penetration and mixing). However, the unique design of the asymmetric pulses (strong positive pulses break down the membrane structure, while weak negative pulses finely adjust the orientation of polar molecules) is indispensable for achieving highly ordered molecular pre-assembly. Symmetric electric fields cannot achieve this directional driving, thus compromising the uniformity and strength of the final structure.

[0242] Comparative Example 10 (without vacuum baking): Thermal disturbance damages fine structure

[0243] Overall deterioration of texture (brittleness 2600, fragmentation energy 10.8): Under normal pressure and high temperature: intense water evaporation generates internal vapor pressure, destroying the already formed fine crystal nuclei and pre-assembled structures. High temperature intensifies molecular Brownian motion, disrupting the molecular order established by the electric field. Rapid crystal coarsening (Ostwald ripening).

[0244] Result: The final result is still a relatively coarse and inhomogeneous crystal structure (14.6 μm), which macroscopically exhibits insufficient brittleness and high fracture energy consumption.

[0245] Comparative Example 11 (lacking quenching): Crystal ripening leads to textural degradation

[0246] Decreased brittleness (2850 vs 3100 g): During slow cooling, the metastable fine β' crystals have enough time to grow, merge, and transform into the more stable β type, resulting in increased crystal size (11.3 μm) and altered intensity distribution.

[0247] Increased fragmentation work (9.5 vs 8.5 mJ): Crystal growth and transformation may lead to changes in interface properties, making the fracture path less smooth.

[0248] Conclusion: Rapid cooling (S6) is the final step in "locking in" the ideal metastable microstructure formed at the end of baking. Without it, all the carefully controlled results from the earlier stages will be partially lost during the cooling phase.

[0249] Comparative Examples 1, 2, 6, 7, 8, 12 (Traditional and Severely Defective Processes): Systematic Failure

[0250] The common characteristics of these comparatives are: low brittleness (1850-2350 g), high fragmentation energy (12.5-15.2 mJ), low brittleness index (0.40-0.57), and high moisture absorption (2.85-3.56%).

[0251] The root cause is that they either completely lack the system of crystal engineering and network construction (as in Comparative Examples 1 and 12), or they are only effective in individual parts but the overall synergistic chain is broken (as in Comparative Examples 2, 6, 7, and 8). Their microstructure is coarse, disordered, and lacks an effective hydrophobic antioxidant network.

[0252] Taking Comparative Example 8 (non-targeted enzymatic hydrolysis) as an example: it contains very few free antioxidants, the oils are extremely prone to oxidation and rancidity, and the oxidation products themselves destroy the crystal structure and produce off-odors; at the same time, it lacks a phenolic amine network and has a high hygroscopicity. Its texture and stability are among the worst of all the comparative examples.

[0253] Moisture absorption rate is a key accelerated testing indicator for predicting a product's ability to maintain its texture (resistance to "toughness") in humid environments.

[0254] The extremely low moisture absorption rate (1.23%) of Example 1 stems from: a dense crystalline network: fine, uniform oil crystals form a continuous, low-porosity hydrophobic phase. A complete phenol-amine cross-linked layer: a dense monolayer or multilayer barrier is formed on the surface of crystals and cell debris, with its hydrophobic portion facing outwards, effectively blocking water molecules. Surface microstructure: vacuum baking may have created a smoother surface with fewer pores.

[0255] The reasons for the increase in comparative moisture absorption rates vary:

[0256] Comparative Example 4 (coarse crystals): has many physical pores.

[0257] Comparative Example 5 (without cross-linked network): Chemical barrier is missing, hydrophilic groups are exposed.

[0258] Comparative Example 1 (Traditional Process): Both are present, so the moisture absorption rate is the highest (3.56%).

[0259] The high brittleness mainly relies on small and uniform crystals (achieved through the synergistic effect of seed crystal S3 + electric field S4 + vacuum baking S5) as the weak points.

[0260] Low fragmentation energy mainly relies on a strong yet brittle phenolamine network (achieved through a synergistic process of targeted enzymatic hydrolysis of S2 + L-arginine S3 + mild cross-linking of S5) to guide brittle fracture and avoid energy dissipation.

[0261] The low moisture absorption rate mainly relies on the hydrophobic barrier effect of the aforementioned phenolic amine network and the physical barrier of the dense crystal structure.

[0262] The uniformity of texture (low data standard deviation) depends on the homogenization effect of electric field S4 and the uniform heat treatment of dynamic humidity control baking S5.

[0263] In any comparative example, disrupting any sub-module of "crystal engineering" or "network chemistry" results in a predictable, specific pattern of degradation in its texture and physical stability data. This rigorous and interpretable correspondence between data and process defects provides the strongest evidence for the non-obviousness and deep synergy of the technical solution of this invention. It demonstrates that the superior performance of the final product does not originate from a single "magic ingredient," but rather from a completely new material system constructed by a set of interconnected and indispensable process logics.

[0264] Experimental Example 3

[0265] 3. Oxidative stability and sensory evaluation of flavor:

[0266] 3.1 Specific methods for oxidative stability analysis: Oxidative stability is assessed by combining accelerated oxidation tests with chemical index determination. Key indicators include peroxide value (POV) and thiobarbituric acid value (TBARS), which indicate the content of primary and secondary oxidation products, respectively.

[0267] According to the Arrhenius equation, increasing the storage temperature can significantly accelerate lipid oxidation, thus predicting the product's shelf life at room temperature in a shorter time. Samples (whole kernels) from each experimental group were placed in a constant temperature and humidity incubator at 60±1℃ and 65±5% relative humidity. Samples were taken on days 0, 7, 14, and 21 of the experiment. After each sampling, the samples were immediately sealed in aluminum foil bags and placed in a -20℃ freezer to stop the oxidation reaction until analysis.

[0268] All oxidation index measurements must be performed using oils extracted from the sample.

[0269] Remove the sample stored at -20℃ and quickly grind it into a fine powder using a mortar cooled with liquid nitrogen. Accurately weigh approximately 5.0 g of sample powder (accurate to 0.0001 g), wrap it in filter paper, and place it in a Soxhlet extractor. Use anhydrous diethyl ether or petroleum ether (boiling range 30-60℃) as solvent and extract by reflux in a water bath for 6-8 hours. After extraction, evaporate the solvent in the receiving flask to dryness using a rotary evaporator in a 40℃ water bath. Cool the obtained oil to room temperature in a desiccator, weigh it, and calculate the oil yield. The extracted oil should be protected from light and used immediately for determination or sealed in a nitrogen-filled amber bottle and stored at -20℃ (for no more than 3 days).

[0270] The sodium thiosulfate titration method (refer to GB 5009.227-2016) was used. Peroxides produced by oil oxidation can oxidize potassium iodide to iodine under acidic conditions. The precipitated iodine was titrated with a standard sodium thiosulfate solution, and the peroxide value was calculated. Reagents: glacial acetic acid-isooctane mixture (3:2, v / v), saturated potassium iodide solution, 0.01 mol / L sodium thiosulfate standard solution, 1% starch indicator.

[0271] The determination method is as follows:

[0272] Weigh 2.00–3.00 g of oil (accurate to 0.0001 g) into a 250 mL iodine flask. Add 30 mL of glacial acetic acid-isooctane mixture and gently shake to dissolve the oil. Add 0.5 mL of saturated potassium iodide solution, stopper the flask, and gently shake to mix. Let the mixture stand in the dark for 3 minutes. Immediately add 30 mL of distilled water and shake well. Titrate with 0.01 mol / L sodium thiosulfate standard solution until a pale yellow color is reached. Add approximately 0.5 mL of starch indicator; the solution will turn blue. Continue titrating until the blue color just disappears, which is the endpoint. Perform a blank test simultaneously.

[0273] POV (meq / kg) = [(V - V0) × C × 1000] / m

[0274] V: Volume of sodium thiosulfate consumed by the sample (mL)

[0275] V0: Volume of sodium thiosulfate consumed in the blank (mL)

[0276] C: Concentration of sodium thiosulfate standard solution (mol / L)

[0277] m: Oil weight (g)

[0278] The results of the oxidative stability test are shown in Table 5:

[0279] Table 5

[0280]

[0281] The results above show that: Example 1: POV growth is extremely slow, with a 21-day POV of only 5.82 meq / kg, far below the industry-common rancidity threshold (10 meq / kg). This indicates that its antioxidant system can effectively block the initiation and transmission of oxidation chain reactions.

[0282] The extremely low TBARS value (0.28) demonstrates that the system not only reduces primary oxidation products but also strongly inhibits the formation of secondary toxic, harmful, and off-flavor carbonyl compounds, which is key to maintaining pure flavor.

[0283] This exceptional stability stems from a triple synergistic barrier of "physical isolation, chemical quenching, and metal chelation." The fine, uniform network of oil crystals (8.2 μm) and the phenol-amine cross-linking layer significantly restrict oxygen diffusion and the migration of oil molecules. Free ellagic acid and its phenol-amine cross-linking products, transformed and immobilized in situ within the network, are highly efficient free radical scavengers and peroxide decomposers. Polyphenols can effectively chelate trace amounts of pro-oxidant metal ions in processing equipment or raw materials.

[0284] Comparative Example 5 (without phenolic amine crosslinking) and Comparative Example 4 (without homologous seed crystals): Both had similar POVs at 14 days (6.20 vs 5.50), but the TBARS value of Comparative Example 5 (0.79) was significantly higher than that of Comparative Example 4 (0.51). Comparative Example 4, due to its larger crystals, experienced faster oxygen diffusion and oil migration, resulting in a faster primary oxidation (POV). However, Comparative Example 5, lacking a crosslinking network, had free antioxidants that were easily consumed and deactivated, leading to a faster progression of the oxidation chain reaction to the stage of producing secondary off-odor products (high TBARS). This demonstrates that the phenolic amine network plays an irreplaceable role in "blocking the depth of oxidation."

[0285] Comparative Example 3 (no electric field) and Comparative Example 9 (improper electric field): Both showed better oxidative stability than most comparative examples, but not as good as Example 1. The absence or improper electric field led to a decrease in the spatial distribution matching between antioxidant molecules (polyphenols) and pro-oxidation sites (lipid interfaces, metal ions), i.e., "uneven deployment of protective forces," which prevented the overall antioxidant network from achieving optimal efficiency.

[0286] Comparative Example 10 (without vacuum baking): Its oxidative stability was significantly worse than that of Example 1, but better than that of the conventional process. This indicates that the vacuum environment not only enhances the flavor, but its oxygen-deficient conditions also directly inhibit thermal oxidation during the baking process, making it an important part of the synergistic system.

[0287] Comparative Example 12 (with TBHQ): Its POV (8.50) and TBARS (1.25) both deteriorated significantly at 14 days, far worse than Example 1. This demonstrates that a single, exogenous antioxidant, no matter how high its initial efficiency, cannot match the multi-layered, adaptive, and tightly bound in-situ antioxidant network system constructed from endogenous components. The depletion or migration of TBHQ leads to a rapid decline in protective efficacy.

[0288] 3.2 Sensory evaluation

[0289] Evaluators: 10-12 selected and trained evaluators.

[0290] Environment: Standard sensory evaluation room, with separate cubicles and white light lighting.

[0291] Sample preparation: Whole kernels for each experimental group were randomly numbered and presented as blind samples.

[0292] Evaluation metrics and scales: A 9-point structured scale (1 = very weak / very poor, 9 = very strong / very good) was used to evaluate the following attributes: crispness, aroma intensity, aroma purity, mouthfeel uniformity, aftertaste (no astringency / runny), and overall acceptability. The mean and standard deviation of the scores for each metric were calculated. Analysis of variance (ANOVA) and multiple comparisons (such as Duncan's test) can be used to determine the significance of differences between groups (p < 0.05).

[0293] The sensory evaluation results are shown in Table 6:

[0294] Table 6

[0295]

[0296] The results above show that Example 1 achieved the highest scores (8.7-8.9) on all sensory indicators with a very small standard deviation (0.2-0.3), demonstrating its excellent sensory quality and high consistency.

[0297] The overall acceptance of all comparative examples was significantly lower than that of Example 1 (the difference was between 1.0 and 2.9 points), which intuitively shows that the absence or replacement of any technical feature would lead to a significant degradation in the sensory experience of the end user.

[0298] The sensory data are highly consistent with the aforementioned data on texture, oxidative stability, and microstructure, forming a complete chain of evidence.

[0299] Example 1 Crispness (8.9) and texture uniformity (8.9): Thanks to the fine and uniform crystal network and the strong phenolic amine cross-linking structure, the evaluators generally described it as "melts in the mouth", "every bite is equally crisp", and "no hard lumps".

[0300] Aroma purity (8.8) and finish (8.8): This is attributed to the precise control of the Maillard reaction by vacuum temperature-controlled roasting, and the effective suppression of lipid oxidation off-flavors (rancidity) and excessive burnt bitterness by the endogenous antioxidant network. Reviewers described it as "pure nutty roasted aroma" and "clean, sweet finish with no astringency." The low standard deviation reflects the extreme improvement in product uniformity achieved by electric field-assisted impregnation and dynamic humidity-controlled roasting.

[0301] Comparative Example 3 (without electric field assistance): Crispness was acceptable (7.5), but texture uniformity was significantly reduced (7.2). The evaluator noted that "some parts were crisper and some parts were slightly tougher," which is consistent with the microstructure of uneven crystal size and low pre-assembly order, proving that the electric field is crucial to the texture uniformity.

[0302] Comparative Example 4 (without homologous seed crystals): scored lowest in crispness (6.8) and uniformity (6.3). The evaluator described it as "a bit hard and difficult to bite through" and "distinctly grainy and a bit gritty." This directly corresponds to its coarse and uneven oil crystals (18.9 μm).

[0303] Comparative Example 11 (without quenching): Crispness (7.8) decreased slightly, and uniformity (7.4) decreased more significantly. The evaluator's feedback that "after cooling, it didn't feel as crisp as when it was freshly made" confirms that slow cooling leads to crystal maturation and structural deterioration.

[0304] Comparative Example 5 (without phenolic amine crosslinking): Its aftertaste score (6.9) was significantly lower than other high-scoring items. The reviewer mentioned that "it smelled very good at first, but left a slightly dry feeling in the throat after eating" and "there was a faint, slightly oily aftertaste." This corresponds perfectly with the oxidative stability data (increased POV and TBARS), indicating that the lack of crosslinking network fixation prevents endogenous antioxidants from maintaining their effectiveness, resulting in oxidative off-flavors appearing in the later stages of oral cavity.

[0305] Comparative Example 10 (without vacuum roasting): Aroma purity (7.5) is its main weakness. The evaluator pointed out that it had a "slight burnt taste" and "the aroma is a bit harsh and not mellow." This is because the Maillard reaction was overdone due to the high temperature at normal pressure, which produced bitter substances such as pyridine and pyrrole, while lipid oxidation was intensified.

[0306] Comparative Example 8 (Non-targeted enzymatic hydrolysis): Several flavor indicators were poor (aroma purity 6.3, aftertaste 5.8). Due to the lack of effective endogenous antioxidants, the product was easily oxidized, and the evaluators clearly reported "rancidity" and "astringency." This demonstrates the positive effect of targeted conversion of tanninase / β-glucosidase on flavor.

[0307] Comparative Example 12 (with TBHQ): The aftertaste (6.5) and aroma purity (6.8) were unsatisfactory. Some reviewers sensitively noticed an "artificial additive taste" or "chemical feel," indicating that exogenous antioxidants may bring negative flavors, and their overall protective effect is far inferior to that of endogenous networks.

[0308] Comparative Example 6 (without pre-fermentation) and Comparative Example 7 (without ozone regulation): Both had low aroma intensity (7.3, 7.4) and purity (7.0, 7.1). This indicates that the lack of precursor substances produced by fermentation or the activation of flavor precursors by ozone makes it difficult to form a rich and top-quality roasted aroma even with subsequent enzymatic hydrolysis.

[0309] While Comparative Examples 9 (inappropriate electric field parameters) and 11 (no quenching) did not have particularly low individual scores, their overall acceptability (7.9, 7.7) could not reach the level of Example 1 (8.9). This indicates that every process parameter must be optimized to a "synergistic point," and any compromise in any step will lower the overall experience.

[0310] While Comparative Example 2 (fermentation and enzymatic hydrolysis only) solved some of the endogenous conversion problems, its sensory performance (7.0) was only slightly better than the traditional process due to the lack of subsequent solidification, assembly, and precise baking steps, and it fell far short of the level of this invention. This proves that the three steps of conversion, assembly, and shaping must be coordinated and interconnected, and none of them can be omitted.

[0311] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A macadamia nut processing method based on the transformation of endogenous components, characterized in that, Includes the following steps: S1: Pre-ferment the raw macadamia nuts in their shells; S2: The microenvironment inside the shell of the fermented fruit is regulated. Specifically, an ozone-argon mixture with an ozone concentration of 10-30 ppm is used to treat the fruit for 15-30 minutes at a pressure of 0.15-0.25 MPa. Then, the shell is broken to remove the kernel and targeted enzymatic hydrolysis is performed. The targeted enzymatic hydrolysis uses an enzyme solution containing tanninase and β-glucosidase. S3: Use the enzyme treatment solution of S2 to prepare an endogenous concentrate, and add high-melting-point triglyceride components and amino acids separated from macadamia nut oil to form a eutectic induction solution; S4: Immerse the kernels treated in S2 into the eutectic induction solution and apply an asymmetric bidirectional pulsed electric field for auxiliary impregnation; S5: The nuts treated with the electric field undergo multi-stage temperature-humidity-vacuum co-ripening and roasting; S6: Season the roasted nuts, cool them quickly, and package them; In S3, the high-melting-point triglyceride component is a component rich in PPP and POP type triglycerides isolated from the same batch of macadamia nut cold-pressed oil, and its addition amount is 3%~8% of the solids of the concentrate; the amino acid is L-arginine, and its addition amount is 0.05%~0.2% of the kernel mass; In S4, the parameters of the asymmetric bidirectional pulsed electric field are: positive pulse intensity 15~25 kV / cm, pulse width 10~20 μs; negative pulse intensity 3~8 kV / cm, pulse width 50~100 μs; frequency 100~200 Hz; processing time 5~15 minutes; processing temperature below 30℃. S5 specifically includes: S51: Molecular cross-linking and maturation stage: Maintain at 45℃~55℃, relative humidity 75%~85%, and slight negative pressure -0.02 ~ -0.05MPa for 1~2 hours; S52: Gradient dehydration and non-enzymatic browning stage: Procedurally reduce humidity to 30%, raise temperature to 80℃~95℃, increase vacuum to -0.06 ~ -0.08 MPa, and maintain for 1~1.5 hours; S53: Low-temperature vacuum precision baking and crystallization stage: Baking for 20~40 minutes at 105℃~118℃, vacuum degree ≤-0.08 MPa, and humidity <10%.

2. The macadamia nut processing method based on endogenous component transformation according to claim 1, characterized in that, In S1, the pre-fermentation treatment uses a symbiotic fermentation agent of Lactobacillus plantarum and Saccharomyces cerevisiae. Fermentation is carried out in a solution containing 2% to 5% fructooligosaccharides at a temperature of 32°C to 37°C for 18 to 36 hours.

3. The macadamia nut processing method based on endogenous component transformation according to claim 1, characterized in that, In S2, during the targeted enzymatic hydrolysis treatment, the dosage of tanninase is 5~20 U / kg kernel, the dosage of β-glucosidase is 10~30 U / kg kernel, the treatment temperature is 35℃~40℃, and the treatment time is 20~40 minutes.

4. The macadamia nut processing method based on endogenous component transformation according to claim 1, characterized in that, In S6, the rapid cooling refers to reducing the core temperature of the kernel to below 10°C within 3 minutes through a low-temperature, high-wind-speed environment of -5°C to 0°C.

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