Method for increasing content of resistant starch and polyphenol through cooperation of ultrasound and infrared enzyme inactivation

Abstract

The invention discloses a method for increasing the content of resistant starch and polyphenol through cooperation of ultrasound and infrared enzyme inactivation, and relates to the technical field of agricultural product and food processing. The method comprises the following steps: selecting and cutting raw materials, treating for 10 minutes at the ultrasonic frequency of 40 kHz, the power of 300 W and the temperature of 60 DEG C, then treating for 50 minutes at the infrared emission wavelength of 4-18 microns, the emission power of 8 kW, the distance between a sample and an infrared plate of 8 cm and the surface temperature of the sample of 60 DEG C, and peeling and cleaning to obtain fresh peeled Chinese yam sections. The inactivation rates of alpha-amylase and beta-amylase are as high as 100% and 95.15% through the innovative design of ultrasonic and infrared treatment and parameter optimization; the contents of total starch and resistant starch are as high as 74.70% and 14.27%; the polyphenol content is 0.69 mg / g, various indexes are obviously higher than those of single heat treatment, single ultrasonic treatment and single infrared treatment, enzyme inactivation is more efficient, and the quality improvement of the Chinese yam is facilitated.

Description

Technical Field

[0001] This invention belongs to the field of agricultural product and food processing technology, specifically relating to a method for simultaneously and efficiently inactivating α-amylase and β-amylase to inhibit starch hydrolysis and increase the content of resistant starch and polyphenols through ultrasound-assisted infrared treatment. Background Technology

[0002] Starch provides a rich source of energy for the human body and, due to its unique physicochemical properties such as viscosity, has broad application prospects in the food processing field. However, endogenous amylases in fresh vegetables (such as α-amylase and β-amylase) readily hydrolyze the starch substrate during processing, reducing its quality and functional properties. α-Amylase is an endoglucosidase that randomly hydrolyzes the α-1,4-glycosidic bonds within starch molecules, producing small sugar molecules such as dextrin and maltose. β-Amylase, on the other hand, is an exoglucosidase that cleaves α-1,4-glycosidic bonds at the maltose level until it encounters an α-1,6-branching point, at which point hydrolysis stops. If the hydrolytic activity of amylase is not precisely controlled, it will lead to the deterioration of the quality of starch-based foods. In addition, resistant starch, as a special form of starch, has special effects such as lowering blood sugar and improving gut health. Polyphenols possess various biological activities, including antioxidant, anti-inflammatory, and antibacterial properties. However, fresh vegetables have low levels of resistant starch, and polyphenols mainly exist in a bound state, bound to starch. Furthermore, the content of both is easily affected by amylase hydrolysis, leading to a decrease in their levels and preventing them from fully exerting their health benefits. Therefore, timely and effective inactivation of amylase activity is a key control point for ensuring product quality, guaranteeing food shelf life, and achieving standardization in industrial production.

[0003] Traditional methods for inactivating amylase include heat treatment (such as blanching and pasteurization) and chemical soaking (such as with citric acid, malic acid, phosphoric acid, and sulfites). However, heat treatment leads to a significant loss of nutrients (such as polyphenols and resistant starch), affecting the nutritional value of yams. Furthermore, high-temperature treatment can cause browning on the surface of yams, affecting their appearance. Chemical treatment can affect the flavor and texture of the product, and chemical residues may be harmful to human health. Some emerging processing technologies, such as high-pressure processing (HPP) and pulsed electric field (PEF) treatment, have also been reported to have potential for enzyme inactivation. While high-pressure processing can effectively inhibit enzyme activity, the high cost of the equipment limits its widespread application in industrial production; pulsed electric fields are less effective for highly conductive or particulate foods, and the equipment maintenance costs are high. Therefore, developing technologies for efficiently inactivating amylase and increasing the content of polyphenols and resistant starch is of great significance for improving the processing quality of starch-based foods.

[0004] Infrared technology has attracted much attention due to its unique advantages of rapid heating, high thermal conversion efficiency, and direct action on the target substance. Studies show that the photothermal effect generated by infrared radiation can achieve localized heating and vibration of enzyme active sites, thereby achieving a "switch-on" regulation effect on enzyme activity, providing a new approach for precise enzyme control. Ultrasonic treatment, through the cavitation effect of ultrasound, can generate a localized, instantaneous high-temperature and high-pressure environment, which can directly act on the enzyme's active sites, disrupting their structure and effectively inactivating the enzyme in a short time. Furthermore, the localized high temperature, high pressure, and strong vibration impact generated by the photothermal effect of infrared radiation and the cavitation effect of ultrasound can also help release bound polyphenols into free polyphenols, better exerting their functional activity. Infrared and ultrasonic treatments can also promote the recrystallization of starch granules, increasing their order and promoting the formation of resistant starch. Therefore, using a gentler power-temperature-time combination, ultrasound combined with infrared treatment has the potential to inactivate amylase activity, increase polyphenol and resistant starch content, thereby better preserving nutrients, ensuring product quality, and enhancing its health benefits. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a method for increasing the content of resistant starch and polyphenols by using ultrasound in synergistic infrared inactivation of enzymes. This method fully leverages the synergistic effect of ultrasound and infrared to efficiently and simultaneously inactivate α-amylase and β-amylase, thereby increasing the content of resistant starch and polyphenols and improving product quality.

[0006] A method for increasing the content of resistant starch and polyphenols by ultrasound-assisted infrared enzyme inactivation, comprising the following steps:

[0007] (1) Raw material selection and cutting: Select fresh yam with no obvious signs of rot, mold or deterioration on the surface, and cut it into sections;

[0008] (2) Ultrasonic treatment: The yam segments obtained in step (1) are placed in an aqueous solution and then subjected to ultrasonic treatment at an ultrasonic frequency of 40 kHz, an ultrasonic power of 120-300 W, and an ultrasonic temperature of 40-80 ℃ for 5-30 min.

[0009] (3) Infrared treatment: Then the yam segments obtained in step (2) are taken out of the water and placed under an infrared plate. They are treated for 6-50 min at an infrared emission wavelength of 4-18 μm, an emission power of 8 kW, a distance of 8 cm between the sample and the infrared plate, and an infrared treatment sample surface temperature of 40-80 ℃.

[0010] (4) Peeling: Peel the yam segments after ultrasonic and infrared treatment in step (3) using a peeling device and rinse them with clean water;

[0011] (5) Packaging: Drain the peeled and cleaned yam segments from step (4), seal them in a package to obtain fresh peeled yam segments, and store them at 0-4 ℃.

[0012] Preferably, the ultrasonic power in step (2) is 300 W, the ultrasonic temperature is 60 ℃, and the processing time is 10 min;

[0013] Preferably, the infrared treatment sample surface temperature in step (3) is 60 °C and the treatment time is 50 min.

[0014] This invention presents an ultrasound-assisted infrared processing method with significant practical implications and broad application prospects. This innovative method, which directly applies physical waves to the target material, efficiently inactivates amylase, inhibits starch hydrolysis, increases polyphenol and resistant starch content, and improves product quality and health benefits. The ultrasound-assisted infrared processing method offers advantages such as efficient enzyme inactivation, significant increase in polyphenol and resistant starch content, and quality improvement. Furthermore, it boasts advantages such as simple equipment operation, safety and environmental friendliness, and low processing costs, making it highly practical and suitable for large-scale industrial production. Therefore, developing this method not only meets consumer demand for healthy foods but also promotes the development of food processing technology, possessing significant scientific and practical value.

[0015] The beneficial effects of this invention are as follows:

[0016] (1) Highly efficient enzyme inactivation to inhibit starch hydrolysis: The ultrasonic-assisted infrared treatment of the present invention can efficiently and simultaneously inactivate α-amylase and β-amylase (inactivation rate up to 100% and 95.15% respectively), which is significantly better than single heat, single ultrasound and single infrared treatment, and can effectively inhibit starch hydrolysis and ensure product quality.

[0017] (2) Increased total starch and resistant starch content: The total starch and resistant starch content of yam treated with ultrasound and infrared synergy (74.70% and 14.27%) were significantly higher than those treated with heat alone, ultrasound alone, and infrared alone, by 1.60% & 3.02%, 2.52% & 2.11%, and 1.90% & 2.07%, respectively. This indicates that ultrasound and infrared synergy treatment can promote the recrystallization of starch granules, increase the formation of resistant starch, thereby increasing the resistant starch content and improving its health function.

[0018] (3) Better preservation of polyphenols: The polyphenol content of yam treated with ultrasound and infrared synergy (0.69 mg / g) was significantly higher than that of other single treatments, by 27.78%, 15%, and 4.55%, respectively. This indicates that ultrasound and infrared synergy treatment can effectively release bound polyphenols, thereby increasing the polyphenol content. This shows that it can better preserve nutrients while inactivating enzymes.

[0019] (4) Facilitates industrial application: The processing technology of this invention is simple, the operating cost is low, the equipment is simple, and the operation steps are not complicated, which facilitates its application in industrial production. It has great advantages in terms of technology and equipment commercialization, standardization, and marketization. It has good application prospects. Detailed Implementation

[0020] The present invention will now be described in further detail with reference to specific embodiments and data. These embodiments are merely illustrative of the technical solutions of the present invention and are not intended to limit the scope of the invention in any way.

[0021] Example 1: Ultrasonic-Infrared Synergistic Processing

[0022] A method for increasing the content of resistant starch and polyphenols by ultrasound-assisted infrared enzyme inactivation, comprising the following steps:

[0023] (1) Raw material selection and cutting: Select fresh yam with no obvious signs of rot, mold or deterioration on the surface, and cut it into sections;

[0024] (2) Ultrasonic treatment: The yam segments obtained in step (1) are placed in an aqueous solution and then subjected to ultrasonic treatment at an ultrasonic frequency of 40 kHz, ultrasonic power of 300 W and ultrasonic temperature of 60 ℃ for 10 min.

[0025] (3) Infrared treatment: Then the yam segments obtained in step (2) are taken out of the water and placed under an infrared plate. They are treated for 50 min at an infrared emission wavelength of 4-18 μm, an emission power of 8 kW, a distance of 8 cm between the sample and the infrared plate, and an infrared treatment sample surface temperature of 60 ℃.

[0026] (4) Peeling: Peel the yam segments after ultrasonic and infrared treatment in step (3) using a peeling device and rinse them with clean water;

[0027] (5) Packaging: Drain the peeled and washed yam segments from step (4), seal them in a package to obtain fresh peeled yam segments, and store them at 0-4 ℃;

[0028] (6) The inactivation rates of α-amylase and β-amylase, total starch content, resistant starch content, polyphenol content, and color change values ​​in the treated samples were measured. The specific results are shown in Table 1-6.

[0029] 1) Method for determining total amylase activity: Accurately weigh 20 g of the treated sample, add 20 mL of pH 5.5 phosphate buffer and crush. Extract at 4 ℃ for a certain time, then centrifuge and collect the supernatant as the enzyme extraction solution. Take 0.4 mL of the enzyme extraction solution and add 3.6 mL of 1.1% soluble starch solution. React at 60 ℃ for 30 min. Quickly pipette 0.5 mL of the reaction solution into a container containing 1.5 mL of DNS solution, incubate in a boiling water bath for 5 min, then rapidly cool. Dilute to 15 mL with deionized water and measure the absorbance at 540 nm to calculate the total amylase activity. The blank solution is prepared by replacing the reaction solution with 0.5 mL of deionized water, with the rest as above. Amylase activity is defined as the amount of enzyme that catalyzes the production of 1 mg of reducing sugar from the substrate in 1 min, which is one enzyme activity unit (U).

[0030]

[0031] Methods for determining the residual activities of α-amylase and β-amylase: The method for determining α-amylase activity utilizes the heat-sensitive nature of β-amylase. The extracted enzyme solution is preheated to 70 °C in a water bath for 15 min to inactivate β-amylase. Then, the activity of α-amylase is determined following the same procedure as for total amylase activity. The activity of β-amylase is calculated using the difference between the total amylase activity and the α-amylase activity.

[0032]

[0033]

[0034]

[0035] In the formula, A1 is the amount of reducing sugar (mg / mL) corresponding to the absorbance value of the enzyme extract; A2 is the amount of reducing sugar (mg / mL) corresponding to the absorbance value of the enzyme extract after 15 min in a 70 ℃ water bath; n is the dilution factor; m is the dry weight of yam (g); t is the reaction time (min); V1 is the total volume of the reaction solution during color development (mL); and V2 is the volume of the reaction solution used during color development (mL).

[0036] 2) Total starch content:

[0037] Preparation of the standard curve: Pipette 1, 2, 3, 4, 5, and 6 mL of 0.5 mg / mL amylose standard solution into six different beakers, add 40 mL of distilled water to each, adjust the pH to 3.5 with 0.1 mol / L HCl solution, and add 1 mL of iodine reagent. Make up to 100 mL with distilled water, let stand for 20 min, and use distilled water as a blank. Measure A at wavelengths λ1 and λ2. λ1 and A λ2 , thus obtaining ΔA直 =A λ2 -A λ1 , with ΔA 直 A standard curve for amylose was prepared with the ordinate as the vertical axis and the amylose content (mg) as the horizontal axis. Using the same method, 6, 8, 10, 12, 14, and 16 mL of 0.5 mg / mL amylopectin standard solution were diluted, the pH was adjusted, 1 mL of iodine reagent was added, and the volume was brought to 100 mL. A content was measured at wavelengths λ3 and λ4. λ3 and A λ4 That is, ΔA 支 =A λ4 -A λ3 , with ΔA 支 A standard curve for amylopectin was prepared by plotting the amylopectin content (mg) on ​​the x-axis.

[0038] Sample Measurement: Weigh 50 mg of the treated sample into a beaker, add 10 mL of 0.5 mol / L KOH solution, heat and stir in a boiling water bath for 30 min until the sample is completely dissolved, then dilute to 100 mL with distilled water. Pipette 15 mL (V2) of the sample solution into two beakers (sample test solution and blank solution), add 30 mL of distilled water to each, adjust the pH to 3.5 with 0.1 mol / L HCl solution, add 1 mL of iodine reagent (no iodine reagent added to the blank solution), and then dilute to 100 mL (V1) for both. Let stand for 20 min, using the blank solution as a control, and measure A. λ1 (535 nm), A λ2 (570 nm), A λ3 (760 nm) and A λ4 (555 nm).

[0039]

[0040] In the formula, x is the amylose / amylopectin content in the sample solution calculated based on the amylose / amylopectin standard curve (mg); V2 is the sample solution volume (mL); V1 is the total volume of the reaction solution (mL); and m is the dry weight of yam (mg).

[0041]

[0042] 3) Resistant starch content: 100 mg of the treated sample was mixed with 4 mL of enzyme solution (1200 U α-amylase and 12 U glucoamylase), shaken in a 37 ℃ water bath for 16 h, centrifuged at 4000 r / min for 10 min, and the supernatant was removed. The precipitate was washed twice with 50% ethanol to remove soluble sugars, and the supernatant was discarded. Then, 2 mL of 2 mol / L KOH solution was added, stirred for 20 min, and then 8 mL of 1.2 mol / L pH 3.8 sodium acetate buffer was added. After mixing, 330 U of glucoamylase was added, and the mixture was incubated in a 50 ℃ water bath for 30 min, centrifuged at 4000 r / min for 10 min, and the supernatant (V1) was collected. The supernatant was appropriately diluted (V2) and reacted with 2 mL of dinitrosalicylic acid in a boiling water bath for 5 min. After cooling, the absorbance was measured at 540 nm. A standard curve was prepared using glucose. The formula for calculating the resistant starch content is:

[0043]

[0044] In the formula, c is the glucose content (mg) obtained from the standard curve; V2 is the sample volume (mL) used for color development; V1 is the total volume of the extract (mL); m is the dry weight of yam (mg); and 0.9 is the coefficient for glucose to starch conversion.

[0045] 4) Method for determining polyphenol content: Weigh a certain amount of the treated sample and extract polyphenols using 80% ethanol aqueous solution. Take 1 mL of the polyphenol extract, add 0.4 mL of Folin-Ciocalteu reagent and 0.8 mL of 10% sodium carbonate solution, and then dilute to 10 mL. Incubate in the dark for 1 h, and measure the absorbance at 760 nm. Use gallic acid as a standard curve. The formula for calculating polyphenol content is:

[0046]

[0047] In the formula: C is the polyphenol concentration (mg / mL) obtained from the standard curve; V is the volume of the polyphenol extract (mL); m is the dry weight of yam (g).

[0048] 5) The colorimetric change value was measured using a fully automatic colorimeter CR-400:

[0049]

[0050] In the formula, ΔE0 represents the surface color of the sample before treatment; ΔE i The surface color of the sample after processing.

[0051] Example 2:

[0052] The experimental treatment process was the same as in Example 1, except that the ultrasonic power was 120 W. The specific results are shown in Table 1.

[0053] Example 3:

[0054] The experimental treatment process was the same as in Example 1, except that the ultrasonic power was 180 W. The specific results are shown in Table 1.

[0055] Table 1. Effect of different ultrasonic powers on amylase inactivation rate

[0056] Example Ultrasonic power (W) α-Amylase inactivation rate (%) β-amylase inactivation rate (%) Example 2 120 <![CDATA[86.77±0.40 c ]]> <![CDATA[40.33±1.39 c ]]> Example 3 180 <![CDATA[97.80±0.20 b ]]> <![CDATA[75.39±0.37 b ]]> Example 1 300 <![CDATA[100±0.9 a ]]> <![CDATA[95.15±0.90 a ]]>

[0057] Comparative analysis of Table 1 revealed that ultrasonic power significantly affected the inactivation rates of both α-amylase and β-amylase. As the ultrasonic power increased from 120 W to 300 W, the inactivation rate of α-amylase increased from 86.77% to 100%, and the inactivation rate of β-amylase increased from 40.33% to 95.15%. This indicates that high-power treatment at 300 W can achieve efficient and simultaneous inactivation of both enzymes (>95%), effectively inhibiting starch hydrolysis and ensuring product quality. Considering the overall inactivation effect on both enzymes, 300 W is the optimal ultrasonic treatment power.

[0058] Example 4:

[0059] The experimental treatment process was the same as in Example 1, except that the ultrasonic temperature was 40 ℃. The specific results are shown in Table 2.

[0060] Example 5:

[0061] The experimental treatment process was the same as in Example 1, except that the ultrasonic temperature was 80 ℃. The specific results are shown in Table 2.

[0062] Table 2. Effect of different ultrasonic temperatures on amylase inactivation rate

[0063] Example Ultrasonic temperature (°C) α-Amylase inactivation rate (%) β-amylase inactivation rate (%) Example 4 40 <![CDATA[80.42±1.31 b ]]> <![CDATA[79.04±0.43 c ]]> Example 1 60 <![CDATA[100±0.9 a ]]> <![CDATA[95.15±0.90 a ]]> Example 5 80 <![CDATA[100±0 a ]]> <![CDATA[93.20±1.63 b ]]>

[0064] Comparative analysis of Table 2 revealed that ultrasonic temperature significantly affected the inactivation rates of both amylases; however, excessively high or low temperatures resulted in poor inactivation. At 60 ℃, the inactivation rate of α-amylase reached 100%, and the inactivation rate of β-amylase reached 95.15% (>95%), achieving efficient and simultaneous inactivation of both enzymes. Therefore, 60 ℃ is the optimal ultrasonic treatment temperature.

[0065] Example 6:

[0066] The experimental treatment process was the same as in Example 1, except that the ultrasonic time was 5 min. The specific results are shown in Table 3.

[0067] Example 7:

[0068] The experimental treatment process was the same as in Example 1, except that the ultrasonic time was 30 min. The specific results are shown in Table 3.

[0069] Table 3. Effect of different sonication times on amylase inactivation rate

[0070] Example Ultrasound time (min) α-Amylase inactivation rate (%) β-amylase inactivation rate (%) Example 6 5 <![CDATA[98.82±0.29 a ]]> <![CDATA[87.18±0.84 b ]]> Example 1 10 <![CDATA[100±0.9 a ]]> <![CDATA[95.15±0.90 a ]]> Example 7 30 <![CDATA[100±0 a ]]> <![CDATA[95.64±124 a ]]>

[0071] Comparative analysis of Table 3 revealed that ultrasonic time significantly affected the inactivation rates of α-amylase and β-amylase. As the ultrasonic time increased from 5 min to 10 min, the inactivation rate of α-amylase gradually increased from 98.82% to 100%; the inactivation rate of β-amylase significantly increased from 87.18% to 95.15% (at 10 min), and then only slightly increased to 95.64% (at 30 min). With the goals of simultaneous and efficient inactivation of both enzymes and cost reduction, 10 min is sufficient for efficient simultaneous inactivation of α-amylase and β-amylase. Further extending the time did not significantly improve the inactivation rate and may even increase energy consumption due to prolonged processing time. Therefore, 10 min is the optimal ultrasonic treatment time.

[0072] Example 8:

[0073] The experimental treatment process was the same as in Example 1, except that the surface temperature of the infrared-treated sample was 40 °C. The specific results are shown in Table 4.

[0074] Example 9:

[0075] The experimental treatment process was the same as in Example 1, except that the surface temperature of the infrared-treated sample was 80 °C. The specific results are shown in Table 4.

[0076] Table 4. Effect of different infrared-treated sample surface temperatures on amylase inactivation rate

[0077] Example Infrared temperature (°C) α-Amylase inactivation rate (%) β-amylase inactivation rate (%) Example 8 40 <![CDATA[78.07±1.62 b ]]> <![CDATA[34.89±0.62 b ]]> Example 1 60 <![CDATA[100±0.9 a ]]> <![CDATA[95.15±0.90 a ]]> Example 9 80 <![CDATA[100±0 a ]]> <![CDATA[97.03±0.86 a ]]>

[0078] Comparative analysis of Table 4 revealed that infrared treatment temperature significantly affected the inactivation rates of α-amylase and β-amylase. As the sample surface temperature increased from 40 °C to 60 °C, the inactivation rate of α-amylase significantly increased from 78.07% to 100%; the inactivation rate of β-amylase significantly increased from 34.89% to 95.15% (10 min), then increased slightly to 97.03% (30 min). At 60 °C, the inactivation effect on both enzymes reached >95%. Although 80 °C further improved the inactivation rates of both enzymes, the increase was not significant and instead increased energy consumption and the risk of product quality deterioration. Therefore, 60 °C is the optimal infrared treatment temperature for sample surfaces.

[0079] Example 10:

[0080] The experimental treatment process was the same as in Example 1, except that the infrared time was 6 minutes. The specific results are shown in Table 5.

[0081] Example 11:

[0082] The experimental treatment process was the same as in Example 1, except that the infrared time was 13 min. The specific results are shown in Table 5.

[0083] Table 5. Effect of different infrared times on amylase inactivation rate

[0084] Example Infrared time (min) α-Amylase inactivation rate (%) β-amylase inactivation rate (%) Example 10 6 <![CDATA[97.16±0.61 b ]]> <![CDATA[85.06±1.06 c ]]> Example 11 13 <![CDATA[98.24±0.29 ab ]]> <![CDATA[89.31±0.93 b ]]> Example 1 50 <![CDATA[100±0.9 a ]]> <![CDATA[95.15±0.90 a ]]>

[0085] Comparative analysis of Table 5 revealed that infrared treatment time significantly affected the inactivation rates of α-amylase and β-amylase. As the infrared treatment time increased from 6 min to 50 min, the inactivation rate of α-amylase gradually increased from 97.16% to 100%, while the inactivation rate of β-amylase significantly increased from 85.06% to 95.15% (> 95%). With the goal of simultaneous and efficient inactivation of both, the inactivation rates of β-amylase at 6 min and 13 min were only 85.06% and 89.31%, respectively, failing to meet the requirements for efficient inactivation. Therefore, 50 min is the recommended infrared treatment time.

[0086] Comparison with Example 1: Single heat treatment

[0087] A method for increasing the content of resistant starch and polyphenols by using a single heat-inactivating enzyme, comprising the following steps:

[0088] (1) Raw material selection and cutting: Select fresh yam with no obvious signs of rot, mold or deterioration on the surface, and cut it into sections;

[0089] (2) Hot water treatment: The yam segments obtained in step (1) are placed in an aqueous solution and then subjected to water bath heating treatment at a temperature of 60 ℃ for 60 min;

[0090] (3) Peeling: Take the yam segments that have been heat-treated in step (2) out of the water, peel them with a peeling device, and rinse them with clean water;

[0091] (4) Packaging: Drain the peeled and washed yam segments from step (3), seal them in a package to obtain fresh peeled yam segments, and store them at 0-4 ℃. See Table 6 for specific results.

[0092] Comparative Examples 2 & 3: Single Ultrasonic Treatment

[0093] A method for increasing the content of resistant starch and polyphenols by using ultrasound-mediated inactivation of enzymes alone, comprising the following steps:

[0094] (1) Raw material selection and cutting: Select fresh yam with no obvious signs of rot, mold or deterioration on the surface, and cut it into sections;

[0095] (2) Ultrasonic treatment: The yam segments obtained in step (1) are placed in an aqueous solution and then subjected to ultrasonic treatment at an ultrasonic frequency of 40 kHz, an ultrasonic power of 300 W, and an ultrasonic temperature of 60 ℃ for 10 min and 60 min.

[0096] (3) Peeling: Take the yam segments that have been ultrasonically treated in step (2) out of the water, peel them with a peeling device, and rinse them with clean water;

[0097] (4) Packaging: Drain the peeled and washed yam segments from step (3), seal them in a package to obtain fresh peeled yam segments, and store them at 0-4 ℃. See Table 6 for specific results.

[0098] Comparison Examples 4 & 5: Single Infrared Processing

[0099] A method for increasing the content of resistant starch and polyphenols by using a single infrared-inactivated enzyme, comprising the following steps:

[0100] (1) Raw material selection and cutting: Select fresh yam with no obvious signs of rot, mold or deterioration on the surface, and cut it into sections;

[0101] (2) Infrared treatment: Then the yam segments obtained in step (1) are placed under an infrared plate and treated for 50 min & 60 min at an infrared emission wavelength of 4-18 μm, an emission power of 8 kW, a distance of 8 cm between the sample and the infrared plate, and an infrared treatment sample surface temperature of 60 ℃.

[0102] (3) Peeling: Peel the yam segments after infrared treatment in step (2) using a peeling device and rinse them with clean water;

[0103] (4) Packaging: Drain the peeled and washed yam segments from step (3), seal them in a package to obtain fresh peeled yam segments, and store them at 0-4 ℃. See Table 6 for specific results.

[0104] Table 6. Effects of different treatments on amylase inactivation rate, color, polyphenols, total starch, and resistant starch content.

[0105] Example Handling method α-Amylase inactivation rate (%) β-amylase inactivation rate (%) Color change value Polyphenol content (mg / g) Total starch content (%) Resistant starch content (%) Compare with Example 1 Heat treatment for 60 min <![CDATA[82.02±0.21 b ]]> <![CDATA[39.15±2.41 e ]]> <![CDATA[5.65±0.16 b ]]> <![CDATA[0.54±0.02 d ]]> <![CDATA[73.11±0.71 b ]]> <![CDATA[11.25±0.08 d ]]> Compare with Example 2 Ultrasonic treatment for 10 min <![CDATA[63.43±0.74 c ]]> <![CDATA[22.52±2.06 f ]]> <![CDATA[2.40±0.19 d ]]> <![CDATA[0.50±0.01 e ]]> <![CDATA[73.06±0.31 b ]]> <![CDATA[9.68±0.14 e ]]> Compare with Example 3 Ultrasonic treatment for 60 min <![CDATA[100±0 a ]]> <![CDATA[74.40±0.10 d ]]> <![CDATA[5.18±0.12 c ]]> <![CDATA[0.60±0.03 c ]]> <![CDATA[72.18±0.40 c ]]> <![CDATA[12.16±0.42 b ]]> Compare with Example 4 Infrared processing for 50 min <![CDATA[99.14±0.40 a ]]> <![CDATA[79.24±0.45 c ]]> <![CDATA[7.23±0.41 a ]]> <![CDATA[0.65±0.03 b ]]> <![CDATA[73.58±0.72 ab ]]> <![CDATA[11.70±0.20 c ]]> Compare with Example 5 Infrared processing for 60 min <![CDATA[100±0 a ]]> <![CDATA[93.21±1.02 b ]]> <![CDATA[7.78±1.12 a ]]> <![CDATA[0.66±0.02 b ]]> <![CDATA[72.80±0.81 c ]]> <![CDATA[12.20±0.32 b ]]> Example 1 Ultrasound combined with infrared processing for 10+50 min <![CDATA[100±0.9 a ]]> <![CDATA[95.15±0.90 a ]]> <![CDATA[7.55±0.41 a ]]> <![CDATA[0.69±0.01 a ]]> <![CDATA[74.70±0.40 a ]]> <![CDATA[14.27±0.37 a ]]>

[0106] Comparative analysis of Table 6 revealed significant differences in the effects of different treatment methods on the inactivation rate of amylase and quality indicators in yam. Regarding amylase inactivation, under the same treatment time, the single heat treatment for 60 min resulted in an α-amylase inactivation rate of 82.02% and a β-amylase inactivation rate of only 39.15% (< 95%), exhibiting the worst inactivation effect. The single ultrasound treatment for 60 min achieved a 100% α-amylase inactivation rate and a β-amylase inactivation rate of only 74.40% (< 95%), lower than the ultrasound-assisted infrared treatment. The single infrared treatment for 60 min achieved a 100% α-amylase inactivation rate, but its effect on β-amylase inactivation was also poor (< 95%). The combined ultrasound and infrared treatment (10+50 min) showed the best effect, achieving a 100% α-amylase inactivation rate and a β-amylase inactivation rate of 95.15% (> 95%), significantly superior to single heat, single ultrasound, and single infrared treatments.

[0107] In terms of quality indicators, the polyphenol content reached 0.69 mg / g, the total starch content reached 74.70%, and the resistant starch content reached 14.27% under ultrasonic combined with infrared treatment, which was significantly higher than other single treatment methods. This indicates that it can better retain nutrients while inactivating enzymes and also has a good protective effect on color.

[0108] This leads to the conclusion that the combined ultrasound and infrared treatment method is superior to single heat, single ultrasound, and single infrared treatment, and is more efficient at deactivating enzymes and improving the quality of yam.

Claims

1. A method for increasing the content of resistant starch and polyphenols by ultrasound-assisted infrared enzyme inactivation, characterized in that... Follow these steps: (1) Raw material selection and cutting: Select fresh yam with no obvious signs of rot, mold or deterioration on the surface, and cut it into sections; (2) Ultrasonic treatment: The yam segments obtained in step (1) are placed in an aqueous solution and then subjected to ultrasonic treatment at an ultrasonic frequency of 40 kHz, an ultrasonic power of 120-300 W, and an ultrasonic temperature of 40-80 ℃ for 5-30 min. (3) Infrared treatment: Then the yam segments obtained in step (2) are taken out of the water and placed under an infrared plate. They are treated for 6-50 min at an infrared emission wavelength of 4-18 μm, an emission power of 8 kW, a distance of 8 cm between the sample and the infrared plate, and an infrared treatment sample surface temperature of 40-80 ℃. (4) Peeling: Peel the yam segments after ultrasonic and infrared treatment in step (3) using a peeling device and rinse them with clean water; (5) Packaging: Drain the peeled and cleaned yam segments from step (4), seal them in a package to obtain fresh peeled yam segments, and store them at 0-4℃.

2. The method for increasing the content of resistant starch and polyphenols by ultrasound-assisted infrared inactivation of enzymes according to claim 1, characterized in that... The ultrasonic power in step (2) is 300 W, the ultrasonic temperature is 60 ℃, and the processing time is 10 min.

3. The method for increasing the content of resistant starch and polyphenols by ultrasound-assisted infrared inactivation of enzymes according to claim 1, characterized in that... In step (3), the infrared treatment raises the sample surface temperature to 60 °C and the treatment time is 50 min.

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