Preparation method of low-oil crispy potato chips based on acetic acid fumigation

Abstract

The application provides a preparation method of low-oil crispy potato chips based on acetic acid fumigation. The steps include: (1) washing and peeling potatoes, cutting into thin slices, further cutting into round slices with a mold, and washing surface starch with deionized water; (2) fumigating with an acetic acid solution for 40-120 min; (3) taking out, blanching the fumigated potato slices in boiling water for 9-11 s, taking out, and draining water to obtain pretreated potato slices; (4) oil frying the pretreated potato slices for 4.5-5.5 min; (5) taking out, draining oil for 10 min, and cooling to room temperature. Through acetic acid fumigation pretreatment, the oil content of the potato chips can be significantly reduced, the crispness can be improved, the color and microstructure integrity can be maintained, and a low-cost, green and practical low-oil crispy potato chip preparation method is provided.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, specifically to a method for preparing low-oil, crispy potato chips based on acetic acid fumigation. Background Technology

[0002] Potato chips, with their unique texture, golden color, and enticing flavor, are beloved by consumers worldwide. However, traditional deep-frying methods result in potato chips with an oil content ranging from 35% to 45%. In this era of food freedom, obesity, cardiovascular disease, and diabetes caused by excessive oil intake have become global public health challenges. The shift from food scarcity to abundance has created an urgent need for developing healthy, low-fat foods. Furthermore, potato chips are fragile during storage and distribution, especially those not packaged with nitrogen, which frequently break, severely impacting their marketability. Therefore, developing green processing technologies that can effectively reduce the oil content of potato chips while significantly improving their crispness and firmness is crucial.

[0003] Pretreatment is a crucial step in reducing the oil content and improving the crispness of potato chips. Current pretreatment methods mainly focus on physical and chemical approaches. Studies have shown that ultrasonic pretreatment can reduce the intercellular spaces and oil surface adhesion coefficient of fried French fries, thereby reducing oil absorption; a combination of basil seed gum coating and ultrasonic (150w) pretreatment can reduce the oil content of potato chips from 26.92% to 14.56%; meanwhile, research has shown that 50×10 3 Pretreatment with ppm CaCl2 solution combined with ultrasound can reduce the oil content of potato chips from 30.3% to 17.2%, but this CaCl2 solution... 2+At certain concentrations, the fried fries had a bitter taste. While ultrasonic treatment was used, it did not significantly reduce oil content in the study; instead, ohmic heating pretreatment reduced the oil content of the potato fries from 32.01% to 26.06%. The study found that microwave pretreatment of potato fries resulted in a higher content of V-shaped starch-lipid complexes during frying, which were distributed on the outer surface of the fries, forming a protective shell that hindered oil penetration. Simultaneously, vacuum drying pretreatment reduced the volume of the fries, making their structure denser and reducing pores, further decreasing oil absorption. Compared to the untreated control group (39.72%), microwave cooking pretreatment for 60 seconds and vacuum drying pretreatment for 240 minutes reduced the oil content of the potato fries by 17.93% and 19.53%, respectively. The study also showed that compared to traditional blanching (95℃, 10 minutes), microwave pretreatment for 60 seconds significantly reduced the oil content. This method not only reduced the oil content of fried French fries from 41.3% to 18.1%, but also improved their hardness, stickiness, and chewiness. Pulsed electric field pretreatment disrupts smaller micropores in the potato chips, merging them into larger ones. This helps increase the rate of moisture evaporation during frying, reduces oil adsorption, and increases the hardness and crispness of the fries, improving their color and thus enhancing their overall quality. Furthermore, researchers have studied the effects of cold plasma, 3D printing, and hot air frying on the oil content, texture, appearance, and sensory qualities of potato chips. While these methods have shown some effectiveness, their high equipment investment costs limit their practicality. For manufacturers, a low-cost, simple-to-operate, and effective green processing technology that reduces oil content and improves crispness is highly desirable.

[0004] Acetic acid (AA), as an acidity regulator, is safe, inexpensive, and widely recognized for its food safety properties. It is well known that adding vinegar when stir-frying shredded potatoes makes them crisper. Based on this, the team's research found that acid treatment enhances potato cell integrity, and 1% AA soaking enhances the potatoes' resistance to boiling. They inferred that acid-induced pectin gelation is the target of acid treatment in improving the heat processing hardness of potatoes. Building on this, researchers investigated the effects of CaCl2 blanching combined with 1% AA soaking, microwave irradiation combined with 1% AA soaking, and ultrasound combined with 1% AA soaking on the quality of potato chips. They found that AA soaking makes the surface of potato chips smoother, reduces pore size, and makes the structure denser, thereby reducing oil absorption. Among the various methods, scalding with 0.3% CaCl2 combined with soaking in 1% AA for 2-8 hours reduced the oil content of potato chips by 10.52%-12.68%; microwave treatment combined with soaking in 1% AA for 4 hours reduced the oil content by approximately 20%; and ultrasonic treatment at 400 W combined with soaking in 1% AA for 1-8 hours reduced the oil content by 21.85%-30.27%. This indicates that AA soaking combined with other pretreatments not only improves the heat processing hardness of potatoes but also reduces the oil content of potato chips. However, traditional soaking methods may result in residual acidity and nutrient leaching. Fumigation, as a gas-phase treatment method, can act more evenly on the material surface, effectively avoiding residual acidity in the product and reducing nutrient loss, while producing almost no wastewater, making it highly practical for enterprises. However, its application potential and mechanism of action in reducing oil content and maintaining crispness in potato chips still lack systematic research.

[0005] Our team's latest research shows that potato pectin solution (3%) begins to gel at pH 4.6 or lower, and acid-induced potato pectin gels exhibit high strength. Based on this research, this study used AA solution (pH 2.4) fumigation (AAF) on potato slices and compared it with AA solution (pH 2.4) soaking (AAI) and blanching in water to systematically explore the effects of AAF on the oil content, texture, color, and microstructure of potato chips. The aim is to elucidate the mechanism by which AAF enhances the oil reduction and crispness retention of potato chips, providing a novel, efficient, and practical technical strategy and theoretical basis for developing low-fat, high-quality fried potato products. Summary of the Invention

[0006] Technical Problem to be Solved: Addressing the issues of high oil content, poor crispness, and brittleness in existing potato chips, while avoiding the potential problems of residual sourness, nutrient loss, and industrial wastewater discharge caused by traditional acetic acid soaking methods, the present invention aims to provide a method for preparing low-oil, crispy potato chips based on acetic acid fumigation. Through acetic acid fumigation pretreatment, the oil content of the potato chips can be significantly reduced, their crispness improved, and good color and microstructure integrity maintained. This provides a low-cost, green, and practical method for preparing low-oil, crispy potato chips.

[0007] Technical solution: A method for preparing low-oil, crispy potato chips based on acetic acid fumigation, comprising the following steps: (1) Wash and peel the potatoes, cut them into thin slices, and then cut them into round slices using a mold. Rinse the surface starch with deionized water. (2) Fumigate with acetic acid solution for 40-120 min; (3) Take out the steamed potato slices and blanch them in boiling water for 9-11 seconds. Remove them, drain the water, and obtain the pre-treated potato slices. (4) Fry the pretreated potato chips for 4.5-5.5 minutes; (5) Remove from the water, drain the oil for 10 minutes, and cool to room temperature.

[0008] Furthermore, the thickness of the sheet in step (1) is 2.5-3.5 mm; the diameter of the disc is 3.5-4.0 cm.

[0009] Furthermore, the acetic acid solution in step (2) has a concentration of 0.5-1.5% (v / v) and a pH of 3.5.

[0010] Furthermore, the acetic acid solution in step (2) has a concentration of 1.0% (v / v) and a pH of 2.4.

[0011] Furthermore, in step (3), the mass ratio of the steamed potato slices to boiling water is 1:9-10.

[0012] Furthermore, the frying process in step (4) specifically involves: waiting for the oil temperature to rise to 180°C and stabilizing it for 10 minutes before frying the potato slices.

[0013] Furthermore, the ratio of potato chips to oil in step (4) is 1g:40-60mL.

[0014] The present invention also provides low-oil, crispy potato chips prepared by the above method.

[0015] Beneficial effects: 1. The present invention uses acetic acid fumigation pretreatment, which significantly reduces the oil content of potato chips by 11.25% compared with the control group, and the oil reduction effect is significant. 2. This invention induces pectin gelation through acetic acid fumigation, enhances the integrity of cell wall structure, and increases the crispness of fried chips by 4.8 times compared to the control group; 3. This invention avoids the problems of residual acidity and nutrient dissolution associated with traditional soaking methods, resulting in a product with a golden color and excellent sensory quality; 4. This invention is simple to operate, requires low equipment investment, and produces almost no wastewater, making it suitable for industrial promotion. Attached Figure Description

[0016] Figure 1 The moisture and oil content of potato chips were compared with those of the control group, acetic acid soaking, and acetic acid fumigation for different times. Among them, (A) represents acetic acid soaking; (B) represents acetic acid fumigation. Note: Different lowercase letters indicate significant differences (P < 0.05). Figure 2 The T2 relaxation time and peak area ratio of moisture in potato chips were used for the control group, AAI (4 h) and AAF (40 min) treatment groups; where (A) is the T2 relaxation time of moisture and (B) is the peak area ratio. Figure 3 Comparison photos of potato chips processed in different ways; Figure 4 SEM images of potato chips with different treatments, magnified 100 times; Figure 5 CLSM diagrams of potato chips with different processing methods; Figure 6 X-ray μCT images of potato chips processed in different ways. Detailed Implementation

[0017] This invention proposes a method for preparing low-oil, crispy potato chips based on acetic acid fumigation. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the following will provide a more detailed description of the invention with reference to specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention.

[0018] The potato variety used was Yunshu 304, purchased from Shiban Logistics Park, Huaxi District, Guiyang City, China. Fresh potatoes with smooth surfaces, uniform size, and no pests or diseases were selected as experimental materials. The rapeseed oil was provided by COFCO Fortune Food Marketing Co., Ltd. (Tianjin, China).

[0019] Digital display constant temperature fryer (BST-81, Bingsite Electric (Jiangsu) Co., Ltd.); Oven (GZX-907MBE, Shanghai Boxun Industrial Co., Ltd.); Freeze dryer (CTFD-10S, Qingdao Yonghe Chuangxin Electronic Technology Co., Ltd.); Spherical Soxhlet extractor (Tianchang Kaiteng Experimental Equipment Co., Ltd.); Low field nuclear magnetic resonance imaging analyzer (NMI20-040V-1, Suzhou Newmai Analytical Instrument Co., Ltd.); Texture analyzer (TMS-Pro type physical property analyzer, FTC Corporation, USA); Colorimeter (D25NC, Shanghai Xinlianchuang Electronic Co., Ltd.); Electron microscope (HITACHI S4800, Hitachi, Tokyo, Japan); Supercritical carbon dioxide dryer (Himatic-250, Harbin Haixing High-tech Instrument Co., Ltd.); Confocal laser scanning microscope (LSM800, Carl Zeiss, Germany); Microtome (RM2016, Leica, Germany); X-μCT (phoenix vtomex m, Waygate Technologies, Germany).

[0020] Example 1 The method for preparing potato chips includes the following steps: (1) Wash and peel the potatoes, cut them into thin slices with a thickness of 3 mm, and further cut them into round slices with a diameter of 3.7 cm using a mold. Rinse the surface starch with deionized water. (2) The samples were divided into 3 groups: Group 1: Control group (CK), fresh-cut potato slices without any treatment, blanched in boiling water for 10 seconds, with a liquid-to-material ratio of 1:10 (w / w). Group 2: Acetic acid soaking group (AAI), soaked in 1.0% (v / v) acetic acid solution (pH 2.4) for 1 h, 2 h, 4 h and 8 h respectively, then removed and blanched in boiling water for 10 s, with a material-to-liquid ratio of 1:10 (w / w). Group 3: Acetic acid fumigation group (AAF), 1.0% (v / v) acetic acid solution (pH 2.4) was used for fumigation for 20 min, 40 min, 60 min, 120 min and 180 min respectively. After being removed, it was blanched in boiling water for 10 s. The material-to-liquid ratio was 1:10 (w / w). (3) The pretreated potato slices were fried in rapeseed oil in a digital display constant temperature fryer. When the oil temperature reached 180℃ and was stabilized for 10 min, 10 potato slices of the same group were put in at a time. The ratio of potato slices to oil was 1:50 (g / mL). The pretreated potato slices were fried for 5 min. (5) Remove from the water and drain the oil in the matching stainless steel oil draining basket for 10 minutes, then cool to room temperature.

[0021] Performance testing: (1) Moisture content determination The moisture content of potato chips before and after frying was determined using the direct drying method according to national standard GB 5009.3-2016. Under normal pressure, potato chips were dried in an oven at 105℃ to constant weight; the decrease in mass was the moisture content. Results are expressed as a percentage.

[0022] (2) Determination of oil content The oil content of potato chips was determined using the national standard Soxhlet extraction method. Before Soxhlet extraction, the potato chips were freeze-dried to remove moisture. The freeze-drying parameters were: temperature -60 ℃, drying time 48 h. The dried sample was then ground and extracted using a 250 mL spherical Soxhlet extractor for 8 h. Oil content is expressed as a percentage (%, dry weight).

[0023] (3) Determination of moisture distribution Method for testing the moisture distribution of potato slices before frying: Place one potato slice (approximately 3 g) into a 40 mm diameter glass tube, and then measure it in a low-field nuclear magnetic resonance imaging analyzer. Parameter settings: RF signal frequency (SF) = 20 MHz, RF 90-degree pulse width (P1) = 7 μs, RF 180-degree pulse width (P2) = 14.48 μs, receiver bandwidth (SW) = 100 kHz, RF delay (RFD) = 0.08 ms, repetition sampling interval (TW) = 4000 ms, analog gain (RG1) = 20, digital gain (DRG1) = 3, preamplifier gain (PRG) = 2, cumulative sampling count (NS) = 4, echo time (TE) = 0.25 ms, number of echoes (NECH) = 15000. The transverse relaxation time of the samples was analyzed using the Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence analysis software. T 2 and relative peak area A 2 .

[0024] (4) Texture determination The textural properties of potato chips were analyzed using a texture analyzer. The hardness, cohesion, elasticity, and chewiness of the chips were determined by compression tests; the maximum modulus (brittleness) of the chips was determined by puncture tests. The compression test used a 25 mm diameter cylindrical probe, with a compression deformation of 40%, a trigger force of 1.5 N, and a test speed of 1 mm / s. The puncture test used a 25 mm diameter stainless steel spherical probe. During the test, the potato chip was placed on a hollow cylindrical platform in the central area, with a test speed of 1 mm / s, a trigger force of 0.5 N, and a puncture distance of 5 mm.

[0025] (5) Color measurement The color of potato chips was measured using a colorimeter, primarily focusing on the color of the central area of ​​the chips. Color was determined by... L * 、a * 、 b * Characterization, in which L * This represents the brightness value (0-100); the higher the value, the brighter the brightness. a * This represents the red-green value; a negative value indicates that the color leans towards green, and a positive value indicates that the color leans towards red. b * The value represents the yellow-blue tint; a negative value indicates a blue tint, and a positive value indicates a yellow tint. The formula for calculating color difference (ΔE) is as follows:

[0026] in L * 、a * 、b * To preprocess the color values ​​of potato chips, L * 0 、a * 0 、b * 0 The color value is for the control group of potato chips.

[0027] (6) Microstructure observation The surface structure of potato chips before and after frying was observed using scanning electron microscopy (SEM). Before frying, the potato chip samples were dehydrated using a supercritical carbon dioxide dryer; after frying, the samples underwent freeze-drying and Soxhlet extraction to remove oil. The treated samples were then fixed onto conductive adhesive and sputter-coated with gold. The microstructure of the samples was observed at an accelerating voltage of 3 kV and a magnification of 100×.

[0028] (7) Oil distribution Microscopic lipid distribution and cell wall structure of potato chips were observed using confocal laser scanning microscopy (CLSM) dual-channel 3D imaging. Thin slices approximately 5 mm × 5 mm × 1 mm in size were cut from the center of the chips using a sharp blade, embedded in paraffin, and then sliced ​​into 5 μm thick sections using a microtome. The slices were stained with Nile Red (3.33 μM), rinsed, and dried, then stained with 4′,6-diamidino-2-phenylindole (DAPI) (5 mg / mL), rinsed, and dried. CLSM imaging was performed with the Nile Red channel at excitation wavelength of 543 nm and emission wavelength of 586 nm, and the DAPI channel at excitation wavelength of 377 nm and emission wavelength of 447 nm. The objective lens was set to 10x magnification, and 3D reconstruction imaging was performed using Z-stack tomography mode. Image processing was performed using Carl Zeiss ZEN software.

[0029] (8) X-ray micro-computed tomography (X-μCT) observation Cross-sections of potato chips were scanned using X-ray μCT. The image acquisition parameters were: voltage 150 kV, current 150 μA, resolution 20.987 μm, and magnification 9.52 × 10⁻⁶. Each sample was rotated 360°. 。 1500 image slices were obtained, each with an exposure time of 0.3 s. The acquired images were reconstructed into a series of 3D images using VG Studio software, and the average cell wall thickness, average porosity, and average pore equivalent diameter of potato chips with different treatments were calculated.

[0030] (9) Data Analysis All experiments were performed at least three times. Data analysis was performed using SPSS 22.0. Data in tables are expressed as mean ± standard deviation. Error bars in all figures correspond to standard deviations. One-way ANOVA and Duncan's multiple comparison test were used to determine significant differences between groups. P < 0.05). The charts were created using Origin 2021 and Adobe Illustrator 2025.

[0031] The results are as follows: (1) Moisture content and oil content The moisture and oil content of potato chips before and after frying were as follows: (This is a direct translation of the first sentence, but the full context is unclear.) Figure 1 As shown in (A) and 1(B), there was no significant difference in the moisture content of potato slices after different times of acetic acid soaking and acetic acid fumigation.P ＞ 0.05). Overall, the moisture content was slightly higher after acetic acid fumigation, mainly due to the different mechanisms of action. Acetic acid soaking directly affects the potato slices, causing slight water loss due to osmotic pressure; while acetic acid fumigation involves the acetic acid molecules gently acting on the surface and shallow layers of the potato slices, resulting in less significant water loss. Significant differences in moisture content were observed between the different treatments after frying. P <0.05), with the highest moisture content in the control group being 0.91%. This result differs from studies showing that the moisture content of fried potato chips is higher than 10%. In this study, the moisture content of fried potato chips was less than 1%, which meets the requirements for crispy potato chips and makes them more resistant to storage.

[0032] During the frying process of potato chips, surface moisture evaporates rapidly, while internal moisture, upon heating, migrates outward as bubbles, forming a porous structure. External oil migrates inward through these pores into the potato chip. During cooling, the pressure difference between the inside and outside of the chip causes surface-adhered oil to penetrate into the porous structure. Furthermore, the roughness of the potato chip surface also affects oil absorption. Figure 1 In (A), the oil content of potato chips soaked in acetic acid for 1 h, 2 h, and 4 h gradually decreased, with the lowest oil content of 35.58% after 4 h of soaking. However, the oil content increased to 41.76% after 8 h of soaking in acetic acid. This may be because the acetic acid solution directly acted on the potato slices for too long, resulting in damage to the cell structure on the slice surface and an increase in oil absorption. Figure 1 In (B), the oil content of potato chips showed a trend of first decreasing and then increasing with the extension of acetic acid fumigation time, reaching its lowest point at 33.09% when the fumigation time was 40 min. The study indicates that acetic acid treatment can make the surface of potato slices smoother and the structure denser, thereby reducing oil absorption and adhesion. The initial moisture content of potato chips treated with acetic acid fumigation was slightly higher than that treated with acetic acid soaking, but the oil content was slightly lower, indicating that the oil content is not only related to the initial moisture content but also affected by the microstructure of the potato chips. Compared with the control group (44.34%), the oil content of potato chips soaked in acetic acid for 4 h and fumigated with acetic acid for 40 min decreased by 8.76% and 11.25%, respectively, showing a significant oil reduction effect.

[0033] Subsequently, acetic acid soaking for 4 h (hereinafter referred to as the AAI group) and acetic acid fumigation for 40 min (hereinafter referred to as the AAF group) were used as optimized processes to further explore the effects of the two on reducing oil and maintaining crispness of potato chips.

[0034] (2) Moisture distribution The moisture distribution of potato chips before frying was determined using LF-NMR. Figure 2 As shown in (A), the relaxation curves of the control group, AAI, and AAF treatment groups all showed only two peaks. 21(0.1-10 ms) represents bound water, which has a high binding energy and low fluidity; T 22 (10-1000 ms) represents free water, with low binding energy and high mobility. A larger T2 value indicates a greater degree of freedom for hydrogen protons, lower binding force, and easier removal of water. Figure 2 (B) It can be seen that, compared with the control group, the bound water (A) of potato slices treated with acetic acid was significantly higher. 21 The increased proportion of free water was mainly due to acid-induced pectin gelation, which trapped some free water in the three-dimensional network and converted it into bound water. The conversion of free water into bound water was particularly significant in the AAI-treated group. P < 0.05), indicating that the pectin gel of potato chips treated with AAI was more thoroughly gelled, and more free water was retained; the free water peak area (A 22 The proportion of oil absorption in potato chips was highest in the control group, at 96.61%. The oil absorption characteristics of potato chips during frying may be related to their moisture state. During frying, bound water is more difficult to lose than free water; therefore, the higher the bound water content, the less space there is for oil to replace the oil in the chips. However, the moisture state during frying is not the only factor affecting oil absorption; it may also be related to pectin gelation and changes in microstructure during pretreatment.

[0035] (3) Texture The texture of potato chips is an important indicator of their sensory quality, and the texture properties of the chips also affect their oil absorption characteristics. Generally, a compact and dense surface structure exhibits higher hardness, a property that effectively inhibits oil absorption. As shown in Table 1, the maximum modulus, hardness, cohesiveness, elasticity, and chewiness of the chips treated with AAI and AAF were all significantly higher than those of the control group. P< 0.05). Maximum modulus, the ratio of maximum puncture force to puncture distance, is used to characterize the brittleness of the frying pellets; a higher value indicates higher brittleness. In Table 1, the frying pellets treated with AAF had the highest maximum modulus, 4.8 times that of the control group, indicating that AAF effectively improves the brittleness of the frying pellets. Secondly, the hardness and cohesion were also higher in the AAF-treated group. Cohesion reflects the internal bonding force of the sample and is characterized by the ratio of the work done in two compressions; the closer the value is to 1, the stronger the internal bonding force and the denser the structure. The AAF-treated group had the highest cohesion at 0.78, indicating strong internal bonding force and a dense structure. In this invention, the hardness, brittleness, and cohesion of the frying pellets treated with AAF are even superior to those treated with AAI. The reason for this difference may be that the AAI treatment involves directly immersing potato slices in an acetic acid solution. The low pH environment causes acid hydrolysis of some protopectin in the cell walls of the potato slice surface, leading to the depolymerization of the rigid structure. Furthermore, the osmotic pressure difference between the acetic acid solution and the potato cells results in slight water loss from the surface cells, causing a decrease in cell turgor pressure. Therefore, the hardness, crispness, and cohesiveness of the fried potato slices are slightly lower than those of the AAF treatment group. The AAF treatment, on the other hand, acts on the surface of the potato slices in a gentler way (pectin gelation), reducing acid hydrolysis and water loss of protopectin, thus effectively improving the texture of the fried potato chips. In Table 1, the AAI treatment group showed the highest elasticity and chewiness, mainly due to the hydrolysis of protopectin that maintains the rigid cell structure under low pH conditions, and the more thorough acid-induced pectin gelation, which increases elasticity. Since chewiness is directly proportional to elasticity, the AAI treatment group also showed the highest chewiness.

[0036] Table 1. Effects of different treatments on the texture of potato chips

[0037] Note: Different lowercase letters represent significant differences. p < 0.05) (4) Color As shown in Table 2 and Figure 3 As shown, the untreated control group potato chips were golden in color and had a reddish hue. a * Value and yellowness b * The highest value was found in the brightness of potato chips after AAI and AAF pretreatment. L * The value is significant ( P < 0.05) increases redness a * Value and yellowness b * Value decreases ( P< 0.05). Specifically, the color of potato chips pretreated with AAI was significantly lighter, with an overall color (ΔE) that differed considerably from the control group. During frying, the Maillard reaction is a crucial step in the color development of the chips. The depth of color in fried potato chips is mainly related to the reducing sugar and amino acid content of the potato slices. During AAI treatment, water-soluble components in potato cells, including reducing sugars and some free amino acids, dissolve, leading to a decrease in the concentration of the Maillard reaction substrate and preventing the formation of large amounts of yellow or brown products. Furthermore, the optimal pH environment for the Maillard reaction is neutral or alkaline; the Maillard reaction rate decreases significantly in acidic environments. Under acidic conditions, the amino groups (-NH2) participating in the Maillard reaction are protonated, forming positively charged ammonium ions (-NH3). + Acetic acid molecules are difficult to condense with the carbonyl groups of reducing sugars, thus inhibiting the Maillard reaction. In AAF treatment, acetic acid molecules are adsorbed in gaseous form onto the surface of potato chips, mainly causing a decrease in the pH of the surface area. This has limited effect on the dissolution of internal reducing sugars and amino acids, therefore the color lightening effect is not as good as AAI treatment.

[0038] Table 2. Effects of different treatment methods on potato chip color

[0039] Note: Different lowercase letters represent significant differences. p < 0.05) (5) Observe the microstructure of potato chips using dual-channel 3D imaging techniques of SEM and CLSM. The microstructure and oil distribution of potato chips were observed using dual-channel 3D imaging techniques, namely SEM and CLSM. Figure 4As shown, after blanching, potato chips exhibited signs of cell collapse, particularly in the control group where cell wall collapse was severe, even producing cracks and holes, with most starch gelatinized. In contrast, potato chips pretreated with AAI and AAF still showed intact cell morphology and ungelatinized starch granules. This is mainly because acid-induced pectin gelatinization enhances the mechanical strength and heat resistance of the cell walls, allowing starch to be better retained within the cells. AAF-pretreated potato chips showed more rounded starch granules, while AAI-treated potato chips showed slight wrinkling at the edge cells. This indicates that AAF treatment is more conducive to maintaining the integrity of potato cells, while AAI treatment, due to the continuous direct action of acetic acid solution from the surface to the interior, may have damaged the surface cells. After frying, clear cell outlines were still visible on the surface of the potato chips, but the cell walls were no longer upright, and the starch was gelatinized. Furthermore, some pores were found on the surface of the potato chips, which were caused by the large amount of water evaporation during frying. The control group had looser surface cells, more cracks, larger pores, and a rougher surface; the AAI and AAF treated groups had tightly connected surface cells with fewer pores, with the AAF group having the smoothest surface and the AAI treated group having a slightly wrinkled surface.

[0040] like Figure 5 As shown in the Clear-field plot, the cell walls of potato chips treated with AAI and AAF were significantly thickened, mainly due to acid-induced pectin gelation. Larger gaps existed between cells in the AAI-treated group, while the cells in the AAF-treated group were more evenly distributed. The DAPI plot visually revealed severe cell wall rupture in the control group after frying, with almost no intact cell wall morphology observed; the cell walls of the AA-treated potato chips were relatively intact, with the AAF-treated group showing the most intact cell wall morphology, fewer ruptures, and more even distribution. In the NielRe plot, the red area represents oil; the brighter the color and the larger the area, the more oil is distributed. The control group had the largest red area, which was clumped together, indicating a high oil content. The oil was distributed not only in surface cells and gaps but also in deeper pores, a phenomenon confirmed by the 3D reconstruction. The AAI-treated group also had a large red area, with oil following the cell shape and mainly distributed in the cell walls and intercellular spaces; the red area in the AAF-treated group was no longer obvious. The above oil distribution and oil content (…) Figure 1The results are largely consistent. The complex field is an overlay of the Clear-field plot, DAPI plot, and NilRe plot, while the 3D plot is a Z-stack tomographic reconstruction image that visualizes the distribution and penetration depth of oils. Both the complex field and 3D plots allow for a clear observation of the cell wall network and oil distribution. In the AAF-treated group, the cell wall outlines are clear and evenly distributed, the cell morphology is intact, the red area is small, and the oil is mainly located in the cell wall. This indicates that the AAF-treated potato slices retain their cell morphology well after frying, and the pectin gelation of the cell wall on the slice surface effectively prevents oil penetration. In contrast, the AAI-treated group, due to direct contact of the acetic acid solution with the potato slices, while achieving thorough pectin gelation, damaged the surface cells, leading to increased oil penetration.

[0041] (6) X-ray micro-computed tomography The oil absorption capacity of potato chips is mainly related to their porous structure. During frying, the oil in the large cavities and cracks is primarily generated by the replacement of water by oil after evaporation, while the absorption of oil in the small pores mainly stems from the vacuum effect during cooling. Figure 6 As shown in Table 3, X-ray microscopic analysis and quantitative measurement of the microstructure of potato chips, including the solid matrix, pores, and oil, were performed using X-ray microscopic coherence tomography (XMT). Due to the different densities of the solid matrix, pores, and oil, they can be distinguished. The solid matrix has the highest density and appears brightest in the image (white); the oil has a medium density and appears moderately bright in the image (gray); and the air has the lowest density and appears darkest in the image (black). Figure 6 A is the original two-dimensional planar diagram of the cross-section of potato chips, which clearly shows the distribution of pores in the chips. The control group has more pores and a higher proportion of large pores. The AAI and AAF treatment groups have relatively fewer pores and a more obvious solid matrix. However, the AAI treatment group clearly has large pores, especially in the surface cells at the edges. This indicates that the direct soaking in acetic acid solution will damage the surface cells of the potato chips, causing starch or nutrients to dissolve and form large cavities. During frying, the water in the large cavities evaporates, and oil enters and replaces the water. Figure 6 The pore distribution is consistent with the quantitative detection results of average porosity and average pore size in Table 3. The average porosity is higher in the control group, and the average pore size is larger in the control group and the AAI treatment group. Figure 6 B is a 3D reconstructed image of the original two-dimensional planar image. In the image, the control group has large and widely distributed pores, the AAI treatment group also has relatively large pores, and the AAF treatment group has small and sparse pores. Figure 6C represents the three-dimensional skeleton of the solid matrix rendered in blue. The blue color is darker in the AAI and AAF treatment groups, indicating a high density and compact structure with thicker cell walls. This is mainly due to the acid-induced pectin gelation effect. Table 3 also confirms this phenomenon; the average cell wall thickness in the AAI and AAF treatment groups is significantly higher than that in the control group. P <0.05). Figure 6 D is a 3D visualization of oil distribution rendered in yellow, corresponding to the pore distribution. The control group has the deepest yellow color, the largest area, and the highest oil content, mainly consisting of large oil droplets. The AAI treatment group also has a relatively deep yellow color and a large area, and similarly contains large oil droplets. The AAF treatment group has a significantly smaller yellow area and a significantly lower oil content. Figure 6 D. Distribution of oil and oil content ( Figure 1 (To maintain consistency) Figure 6 E shows a 3D rendering of the mixture of oil and matrix skeleton, clearly presenting the proportion of oil. The control group had the highest proportion, followed by the AAI treatment group, and the AAF treatment group had the lowest proportion. In the AAF treatment group, the oil was mainly distributed on the surface of the fried slices. It is speculated that acetic acid molecules mainly act on the surface of potato slices, causing the pectin in the surface cell walls to gel, tightly connecting the cells together and forming a "shell" during frying, effectively preventing the oil from penetrating. In contrast, during the AAI treatment, the acetic acid solution directly acts on the potato slices, causing the cell wall pectin to gel from the surface inward. Due to excessive contact with the acetic acid solution, some of the protopectin in the cell walls undergoes acid hydrolysis, the rigid structure depolymerizes, the surface cells are damaged, and starch or nutrients dissolve to form large cavities, allowing oil to enter.

[0042] Table 3. Quantitative parameters of potato chips calculated based on X-ray diffraction microscopy.

[0043] Note: Different lowercase letters represent significant differences. p < 0.05) In summary, this study compared the effects of acetic acid fumigation and acetic acid soaking on reducing oil content and maintaining crispness in potato chips. The results showed that compared to blanching in water, acetic acid fumigation for 40 min and acetic acid soaking for 4 h reduced the oil content of potato chips by 11.25% and 8.76%, respectively, and increased the crispness by 3.80 times and 3.20 times, respectively, significantly improving crispness while reducing oil content. The microstructure and oil distribution of potato chips were observed using SEM, CLSM dual-channel 3D imaging technology, and X-μCT technology. It was found that AAI and AAF pretreatment could better maintain the cell morphology of potato chips. Among them, the cell wall outline of potato chips treated with AAF was the clearest, the distribution was uniform, the porosity was the lowest (9.85%), the surface was smooth, and the oil distribution was the least. In contrast, the water blanching group had severe cell wall rupture, structural collapse, cracks and pores, with more macropores (222.39 μm) and high porosity (28.61%). The surface of the chips was rough, and the oil was distributed not only in the surface cells and gaps, but also in the deep pores. AAI-treated potato chips exhibit thorough pectin gelation, resulting in high bound water content and excellent elasticity and chewiness after frying. However, the direct contact between the potato chips and the acetic acid solution causes acid hydrolysis of the protopectin in the cell walls of the slices, leading to the depolymerization of the rigid structure, the dissolution of nutrients and starch, and the formation of large pores (150.04 μm), which in turn increases the oil content. Overall, AAF-treated potato chips not only have low oil content and high crispness but also a golden color. The process is simple, the processing time is short, and industrial wastewater is minimal, providing a simple, feasible, and effective strategy for producing low-fat, high-quality fried potato products.

[0044] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the technical solutions of the present invention, shall still fall within the scope of protection of the present invention.

Claims

1. A method for preparing low-oil, crispy potato chips based on acetic acid fumigation, characterized in that, Includes the following steps: (1) Wash and peel the potatoes, cut them into thin slices, and then cut them into round slices using a mold. Rinse the surface starch with deionized water. (2) Fumigate with acetic acid solution for 40-120 min; (3) Take out the steamed potato slices and blanch them in boiling water for 9-11 seconds. Remove them, drain the water, and obtain the pre-treated potato slices. (4) Fry the pretreated potato chips for 4.5-5.5 minutes; (5) Remove from the water, drain the oil for 10 minutes, and cool to room temperature.

2. The method for preparing low-oil, crispy potato chips based on acetic acid fumigation according to claim 1, characterized in that, The thickness of the sheet in step (1) is 2.5-3.5 mm; the diameter of the disc is 3.5-4.0 cm.

3. The method for preparing low-oil, crispy potato chips based on acetic acid fumigation according to claim 1, characterized in that, The acetic acid solution in step (2) has a concentration of 0.5-1.5% (v / v) and a pH of 3.

5.

4. The method for preparing low-oil, crispy potato chips based on acetic acid fumigation according to claim 1, characterized in that, The acetic acid solution in step (2) has a concentration of 1.0% (v / v) and a pH of 2.

4.

5. The method for preparing low-oil, crispy potato chips based on acetic acid fumigation according to claim 1, characterized in that, The mass ratio of the steamed potato slices to boiling water in step (3) is 1:9-10.

6. The method for preparing low-oil, crispy potato chips based on acetic acid fumigation according to claim 1, characterized in that, The frying process in step (4) specifically involves: waiting for the oil temperature to rise to 180°C and stabilizing for 10 minutes before frying the potato chips.

7. The method for preparing low-oil, crispy potato chips based on acetic acid fumigation according to claim 1, characterized in that, The ratio of potato chips to oil in step (4) is 1g:40-60mL.

8. Low-oil crispy potato chips prepared by the method according to any one of claims 1-7.

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