Instant rehydratable potato sheet and method of making same

Abstract

The application provides a kind of quick rehydration potato dried noodle and its preparation method, and belongs to the technical field of food processing.The gelatin is mixed with water, swells, then is stirred to dissolve, and potato starch is added and mixed evenly.The mixed slurry is poured into a mold and steamed in boiling water, then cooled and dried to obtain the potato dried noodle.The potato dried noodle prepared by the application has more pores on the surface and inside, and the water molecules can be combined more closely with the molecules in the potato dried noodle by adding gelatin.Compared with pure potato dried noodle, the rehydration time of the potato dried noodle provided by the application can be shortened by up to 54.64%.The addition of gelatin also improves the nutritional value of the potato dried noodle.The application provides a convenient, economical and environmentally friendly strategy to improve the quality of potato dried noodle.

Description

Technical Field

[0001] This invention belongs to the field of food processing technology, and in particular relates to a rapid rehydration method for potato starch sheets and its preparation method. Background Technology

[0002] Noodles are a beloved staple food. Among them, potato starch noodles are particularly popular with consumers due to their good extensibility and high transparency. Potato starch noodles are made from potato starch through mixing, steaming, cooling, and drying. Considering consumer acceptance, the cooking and texture characteristics of the noodles must be taken into account during the production process. Generally, dried potato noodles need to be cooked before consumption. However, the excessively long rehydration time for dried potato noodles (11-14 minutes for dried noodles with a diameter of 2mm) is considered a major bottleneck restricting the development of the dried potato noodle industry.

[0003] To address the difficulty of rehydrating dried starch noodles, their cooking properties have been improved. Currently, adding modified starch is an effective strategy to improve starch texture and cooking quality. Ma et al. (2021) found that adding heat-treated corn starch to wheat noodles effectively shortened the rehydration time. R. Jia et al. (2022) reported that using steam-modified potato starch to prepare dried potato sheets reduced the rehydration time from 12.25 min to 8.85 min. Other researchers added 20% hydroxypropyl starch to rice noodles and found that the rehydration time decreased from 16.17 min to 13.33 min (YZJia et al., 2022). Furthermore, studies have reported that forming a porous structure in noodles can effectively shorten the rehydration time. Adding oil gel to hot-air dried noodles creates a porous microstructure, accelerating water penetration and shortening the rehydration time. JPLi, Jiao, Deng, Rashed, and Jin (2018) added a medium-temperature amylase to extruded instant noodles to degrade starch and form a porous structure, reducing the rehydration time from 6 min to 2.75 min, a reduction of 54.17%. Although the above methods shortened the rehydration time, the composition of pure starch noodles is relatively simple: only starch has low nutritional value.

[0004] Gelatin is a protein produced by the partial hydrolysis of collagen and is considered a high-quality protein. Due to its excellent thickening, foaming, and water-retaining properties, gelatin is widely used in the food industry. Therefore, research on using gelatin to prepare potato starch sheets with high nutritional value and easy rehydration will help promote the development of the potato starch industry. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a method for preparing potato starch sheets, which results in potato starch sheets with high nutritional value and fast rehydration speed.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] A method for preparing potato starch sheets includes the following steps: mixing gelatin with water until it swells, then stirring until dissolved, adding potato starch and mixing well, pouring the mixed slurry into a mold and steaming it with boiling water, then cooling and drying to obtain potato starch sheets.

[0008] Preferably, the mass ratio of potato starch to gelatin is 90:10-80:20.

[0009] Preferably, the mass ratio of the gelatin and potato starch mixture to water is 35:65-50:50.

[0010] Preferably, the gelatin swells for 15-40 minutes after being mixed with water.

[0011] Preferably, the gelatin is stirred at 40-55°C after swelling, and the stirring rate is 800-1500 rpm.

[0012] Preferably, the slurry is steamed for 3.5-5 minutes after being poured into the mold.

[0013] Preferably, the drying process is carried out at 40-55°C for 3-5 hours.

[0014] Another object of the present invention is to provide a potato starch sheet, which is prepared by the above-described preparation method.

[0015] Preferably, the moisture content of the potato starch sheet is 10-15%.

[0016] Preferably, the pore diameter of the potato starch skin is 40-200 μm.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] This invention provides a potato starch sheet, in which potato starch is combined with gelatin at a certain concentration to form a dry potato starch sheet with a porous structure, which can shorten the cooking time. Compared with pure potato starch sheet, the rehydration time of the potato starch sheet provided by this invention can be shortened by up to 54.64%. Furthermore, the dry potato starch sheet of this invention has an increased number of pores, with pore sizes between 40-200 μm. By adding gelatin, this invention loosens the starch aggregate structure, and this loose structure facilitates the diffusion of water during the cooking process of the dry potato starch sheet, significantly improving its rehydration properties. Simultaneously, gelatin, as a high-quality protein, increases the nutritional value of the dry potato starch sheet when added. Attached Figure Description

[0019] Figure 1Gelatinization curves of potato starch (PSG) with different gelatin contents (a) and gelatinization curves of diluted potato starch (PS) without added gelatin (b);

[0020] Figure 2 Normal optical micrograph of potato starch paste containing gelatin: PSG 100:0 (a) PSG 95:5 (b) PSG 90:10 (c) PSG 85:15 (d) PSG 80:20 (e);

[0021] Figure 3 Storage modulus G′, loss modulus G″(a) and loss factor tanδ(b) of potato starch with different gelatin contents;

[0022] Figure 4 : The cooking water for potato starch sheets with different gelatin contents;

[0023] Figure 5 : Tensile properties of potato starch sheets with different gelatin contents;

[0024] Figure 6 T2 for potato starch sheets with different gelatin contents, where the arrow indicates T. 2b and T 21 Changes;

[0025] Figure 7 Surface (ae) and cross-sectional (fj) SEM images of potato starch sheets with different gelatin contents: PSGN 100:0 (a,f), PSGN 95:5 (b,g), PSGN 90:10 (c,h), PSGN 85:15 (d,i), PSGN 80:20 (e,j);

[0026] Figure 8 : Thermal properties of potato starch sheets with different gelatin concentrations and those with luminescent gelatin;

[0027] Figure 9 XRD patterns of potato starch sheets with different gelatin concentrations and those with luminescent gelatin.

[0028] Figure 10 FTIR (a) and deconvolution (b) of potato starch sheets with different gelatin concentrations and those with light-sensitive gelatin.

[0029] Figure 11 SAXS spectra (a) and Kratky plots (b) of potato starch sheets with different gelatin concentrations. Detailed Implementation

[0030] This invention provides a method for preparing potato starch sheets, comprising the following steps: mixing gelatin with water until swollen, then stirring until dissolved; adding potato starch and mixing well; pouring the mixture into a mold and steaming in boiling water; cooling and drying to obtain potato starch sheets. This invention utilizes gelatin to prepare potato starch sheets with a porous structure, which can shorten the steaming time of the potato starch sheets, and the resulting dried potato starch sheets have a short rehydration time and high nutritional value.

[0031] In this invention, the mass ratio of potato starch to gelatin is 90:10-80:20, preferably 88:12-83:17. Gelatin and potato starch interact through hydrogen bonds, but this hydrogen bond interaction inhibits the formation of the starch double helix structure to a certain extent. The potato starch to gelatin ratio provided by this invention can effectively improve the quality of potato starch sheets.

[0032] In this invention, the mass ratio of the gelatin and potato starch mixture to water is 35:65-50:50, preferably 40:60-45:55. This invention has found that, since starch is the main contributor to the gel network, changes in solids concentration alter the gel network of the potato starch sheet, thus affecting its quality. The ratio provided by this invention enables the preparation of high-quality potato starch sheets.

[0033] In this invention, the gelatin is mixed with water and swelled for 15-40 minutes, preferably 20-35 minutes.

[0034] In this invention, the gelatin is swollen and then stirred at 40-55°C at a stirring rate of 800-1500 rpm, preferably at 45-50°C at a stirring rate of 1000-1200 rpm.

[0035] In this invention, the slurry is steamed for 3.5-5 minutes after being poured into the mold, and the steaming is carried out after the water boils. As one feasible method, the slurry is poured into a silicone mold with dimensions of 8cm × 1.8cm × 0.2cm.

[0036] In this invention, the drying process involves drying at 40-55°C for 3-5 hours; preferably, the drying process involves drying at 45-50°C for 3.5-4.5 hours. As another possible method, the steamed rice noodles are cooled to room temperature before drying, which is performed using an oven.

[0037] The present invention also provides a potato starch sheet, which is prepared by the above-described preparation method.

[0038] In this invention, the moisture content of the potato starch sheet is 10-15%, preferably 12-13%.

[0039] In this invention, the pore diameter of the potato starch skin is 40-200 μm.

[0040] The potato starch sheets of this invention have numerous pores on their surface and inside, significantly shortening the rehydration time and maintaining the ideal texture of the sheets. The addition of gelatin also enhances the nutritional value of the dried potato starch sheets.

[0041] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0042] Example 1

[0043] A method for preparing potato starch sheets

[0044] The mass ratio of potato starch to gelatin is 90:10.

[0045] Mix 0.6g of gelatin with 9g of distilled water and allow it to swell at room temperature for 30 minutes. Then, stir at 1000 rpm at 50°C until the gelatin is completely dissolved. Add 5.4g of potato starch and stir rapidly with a glass rod to generate uniform bubbles in the mixture. Pour the mixed slurry into a silicone mold (8cm×1.8cm×0.2cm), steam for 4 minutes after the water boils, and then cool to room temperature. Dry in an oven at 45°C for 4 hours until the moisture content is 12% to obtain dried potato starch sheets.

[0046] Example 2

[0047] A method for preparing potato starch sheets

[0048] The mass ratio of potato starch to gelatin is 85:15.

[0049] Mix 0.9g of gelatin with 9g of distilled water and allow it to swell at room temperature for 30 minutes. Then, stir at 1000 rpm at 50°C until the gelatin is completely dissolved. Add 5.1g of potato starch and stir rapidly with a glass rod to generate uniform bubbles in the mixture. Pour the mixed slurry into a silicone mold (8cm×1.8cm×0.2cm), steam for 4 minutes after the water boils, and then cool to room temperature. Dry in an oven at 45°C for 4 hours until the moisture content is 12% to obtain dried potato starch sheets.

[0050] Example 3

[0051] A method for preparing potato starch sheets

[0052] The mass ratio of potato starch to gelatin is 80:20.

[0053] Mix 1.2g of gelatin with 9g of distilled water and allow it to swell at room temperature for 30 minutes. Then, stir at 1000rpm at 50℃ until the gelatin is completely dissolved. Add 4.8g of potato starch and stir rapidly with a glass rod to generate uniform bubbles in the mixture. Pour the mixed slurry into a silicone mold (8cm×1.8cm×0.2cm), steam for 4 minutes after the water boils, and then cool to room temperature. Dry in an oven at 45℃ for 4 hours until the moisture content is 12% to obtain dried potato starch sheets.

[0054] Example 4

[0055] A method for preparing potato starch sheets

[0056] The mass ratio of potato starch to gelatin is 85:15.

[0057] Mix 0.9g of gelatin with 9g of distilled water and allow it to swell at room temperature for 20 minutes. Then, stir at 1200 rpm at 45°C until the gelatin is completely dissolved. Add 5.1g of potato starch and stir rapidly with a glass rod to generate uniform bubbles in the mixture. Pour the mixed slurry into a silicone mold (8cm×1.8cm×0.2cm), steam for 4.5 minutes after the water boils, and then cool to room temperature. Dry in an oven at 50°C for 3.5 hours until the moisture content is 14%, to obtain dried potato starch sheets.

[0058] Comparative Example 1

[0059] A method for preparing potato starch sheets

[0060] The mass ratio of potato starch to gelatin is 95:5.

[0061] Mix 0.3g of gelatin with 9g of distilled water and allow it to swell at room temperature for 30 minutes. Then, stir at 1000 rpm at 50°C until the gelatin is completely dissolved. Add 5.7g of potato starch and stir rapidly with a glass rod to generate uniform bubbles in the mixture. Pour the mixed slurry into a silicone mold (8cm×1.8cm×0.2cm), steam for 4 minutes after the water boils, and then cool to room temperature. Dry in an oven at 45°C for 4 hours until the moisture content is 12% to obtain dried potato starch sheets.

[0062] Comparative Example 2

[0063] A method for preparing potato starch sheets

[0064] The mass ratio of potato starch to soy protein isolate is 90:10.

[0065] Mix 0.6g of soy protein isolate with 9g of distilled water and allow it to swell at room temperature for 30 minutes. Then, stir at 1000 rpm at 50°C until the gelatin is completely dissolved. Add 5.4g of potato starch and stir rapidly with a glass rod to generate uniform bubbles in the mixture. Pour the mixed slurry into a silicone mold (8cm×1.8cm×0.2cm), steam for 4 minutes after the water boils, and then cool to room temperature. Dry in an oven at 45°C for 4 hours until the moisture content is 12% to obtain dried potato starch sheets.

[0066] Comparative Example 3

[0067] A method for preparing potato starch sheets

[0068] The mass ratio of potato starch to whey protein isolate was 90:10.

[0069] Mix 0.6g of whey protein isolate with 9g of distilled water and allow it to swell at room temperature for 30 minutes. Then, stir at 1000 rpm at 50°C until the gelatin is completely dissolved. Add 5.4g of potato starch and stir rapidly with a glass rod to generate uniform bubbles in the mixture. Pour the mixed slurry into a silicone mold (8cm×1.8cm×0.2cm), steam for 4 minutes after the water boils, and then cool to room temperature. Dry in an oven at 45°C for 4 hours until the moisture content is 12% to obtain dried potato starch sheets.

[0070] Comparative Example 4

[0071] A method for preparing potato starch sheets

[0072] The mass ratio of potato starch to pea protein is 90:10.

[0073] Mix 0.6g of pea protein with 9g of distilled water and let it swell at room temperature for 30 minutes. Then, stir at 1000 rpm at 50°C until the gelatin is completely dissolved. Add 5.4g of potato starch and stir rapidly with a glass rod to generate uniform bubbles in the mixture. Pour the mixed slurry into a silicone mold (8cm×1.8cm×0.2cm), steam for 4 minutes after the water boils, and then cool to room temperature. Dry in an oven at 45°C for 4 hours until the moisture content is 12% to obtain potato starch sheets.

[0074] Example 5

[0075] This embodiment tested the properties of a mixture of potato starch and gelatin.

[0076] 1. Materials

[0077] Potato starch (28.0% amylopectin) was purchased from Qingdao Wanjiahe Food Co., Ltd. Gelatin (Type A pigskin) was purchased from Binzhou Jinhengda Gelatin Co., Ltd. (Binzhou, China). Unless otherwise specified, all other reagents were analytical grade, and deionized water was used.

[0078] 2. Pretreatment

[0079] Using the same mass ratio of potato starch to gelatin as in Examples 1-3 and Comparative Example 1, the two were mixed evenly separately. 1.5g of the mixture was dissolved in 26.5g of deionized water, and this mixture was denoted as PSG. 90:10 PSG 85:15 PSG 80:20 PSG 95:5 Take 1.5g, 1.425g, 1.35g, 1.25g, and 1.2g of potato starch and dissolve them in 26.5g, 26.575g, 26.65g, 26.75g, and 26.8g of deionized water, respectively, and label them as PSG. 100:0 PS 95％ PS 90％ PS 85％ PS 80％ A total of 9 sets of experimental samples were obtained.

[0080] 3. Gelatinization characteristics

[0081] The gelatinization properties of the nine experimental samples were evaluated using a rapid viscosity analyzer (RVA-4, Newport Scientific, Warriewood, Australia). The samples were heated from 50°C to 90°C and then cooled to 50°C using programmed heating and cooling, with continuous stirring at 160 rpm throughout the process (Singh, Sodhi, & Singh, 2009). RVA curves were recorded to obtain peak viscosity, breakdown viscosity, final viscosity, and settling time.

[0082] The morphology of potato starch / gelatin pastes obtained from RVA was observed under bright light using an optical microscope (Nikon Instruments Inc., Melville, NY, USA): Nine experimental sample pastes, evaluated using a rapid viscosity analyzer, were dropped onto glass slides and covered with clean coverslips. The particle morphology of the samples was observed under a 200x magnifying glass. Results are as follows: Figure 1-2 As shown in Table 1.

[0083] Table 1. Pasteurizing properties of diluted potato starch with different gelatin contents and without added gelatin.

[0084]

[0085] Note: Data are expressed as mean ± standard deviation (n=3). Mean differences between different letters (ai) within the same column are statistically significant (p<0.05). ND indicates not detected.

[0086] Gelatinization curves and properties of potato starch with different gelatin contents, as follows: Figure 1 As shown in a and Table 1, the RVA curves of the potato starch paste with added gelatin showed a significantly different shape compared to those of pure potato starch, with the viscosity increasing. The viscosity curve decreased with increasing gelatin content. The peak viscosity of the potato starch paste with added gelatin was 3034.00 ± 34.22 cP (PSG). 100:0 The value decreased to 302.33 ± 6.11 cP (PSG). 80:20 The viscosity decreased by approximately 10 times. The final viscosity value decreased from 1733.33 ± 27.79 cP (PSG). 100:0 The value decreased to 412.00 ± 2.65 cP (PSG). 80:20 Decomposition is often used as an indicator of the stability of cooked starch paste. The addition of gelatin caused the viscosity curve of starch to continuously increase during heating and cooling, and no decay value was detected in the sample, indicating that the gelatin potato starch paste has good thermal stability.

[0087] The gelatinization curves and properties of diluted potato starch without added gelatin were measured. Figure 1 (b and Table 1). The viscosity curve of the diluted starch was similar to that of the original potato starch. The total viscosity value on the curve decreased proportionally with decreasing starch concentration. The peak viscosity decreased from 3034.00 ± 34.22 cP (PSG) 100:0 The value decreased to 2462.00±36.77 cP (PS). 80％ The final viscosity was 1733.33 ± 27.79 cP (PSG). 100:0 The value decreased to 1461.33 ± 24.04 cP (PS). 80％ The degradation and retrogradation values ​​of diluted potato starch were significantly reduced. At the same starch content, there were significant differences in the gelatinization parameters between the potato starch / gelatin mixture and the diluted potato starch, confirming that the change in gelatin viscosity was due to the addition of gelatin.

[0088] The morphology of the starch paste was observed under a light microscope after the RVA test. Figure 2 Pure potato starch paste did not contain any starch granules with a specific shape, indicating that the starch granules were completely dissolved after the RVA test. Other starch pastes mixed with gelatin consisted of swollen starch granules. As the gelatin content increased, the number of swollen starch granules increased, resulting in no breakup value in the RVA curve. The retrogradation value represents the viscosity change caused by the recombination of amylose molecules during cooling. After adding gelatin, the retrogradation value of the sample showed a trend of first increasing and then decreasing (PSG).95:5 This indicates that the recrystallization of amylose during the cooling stage is related to the gelatin content. The reason may be that after absorbing water, the gelatin forms a gelatinous system, reducing the amount of water entering the microcrystalline region of the starch granules and, to some extent, inhibiting the expansion and breakage of the starch granules.

[0089] 4. Gel texture properties

[0090] Following RVA analysis, the potato starch / gelatin experimental sample paste was poured into a circular mold (4.0 cm in diameter, 1.5 cm in height) and sealed at 4°C for 12 hours. Texture properties were measured using a texture analyzer equipped with a P / 75 probe (TA, XT Plus, Stable Micro Systems, Surrey, UK), as described by Gao et al. (2023). Texture indices, including hardness, elasticity, cohesion, viscosity, chewiness, and resilience, were obtained. Data were recorded after two compressions at 30% strain.

[0091] Table 2. Texture properties of potato starch gels with different gelatin contents

[0092]

[0093] Note: Data are expressed as mean ± standard deviation (n=3). The means of different letters (ae) in the same column are significantly different (p<0.05).

[0094] Table 2 shows that the hardness of the composite gel increases with increasing gelatin content. Compared with pure potato starch gel, the hardness of the composite gel with a gelatin content of 20% is 78.78 ± 3.05 g (PSG). 100:0 The concentration was increased to 176.56 ± 6.40 g (PSG). 80:20 The elasticity of the sample increased by 2.24 times, from 0.83 ± 0.03 (PSG). 100:0 The value was increased to 0.94 ± 0.02 (PSG). 90:10 This indicates that the elasticity of the potato starch / gelatin composite gel is higher than that of the pure potato starch gel. Furthermore, with increasing gelatin content, the adhesiveness, chewiness, and resilience all improve. This suggests that the composite hydrogel is more chewy than pure potato starch hydrogel, and its structure is less prone to disruption. This is because gelatin forms a gel at low temperatures, creating a dual-network structure, which makes the composite gel harder.

[0095] 5. Rheological properties

[0096] To characterize the mechanical properties of the gels formed after cooling potato starch pastes with different gelatin contents to room temperature, their rheological properties were measured. The rheological properties of the potato starch / gelatin experimental sample pastes after RVA were measured at 25℃ using an interfacial rheometer (MCR102, Anton Paar, Austria). The measurement procedure was based on a previously established method (JYZhang et al., 2022). Immediately after the RVA test, the paste was poured onto the sample stage and allowed to stand at 25℃ for 5 min. The distance between the parallel plate and the sample stage was set to 1 mm, and excess paste was wiped off the plate. The lid was placed to reduce moisture loss. Frequency scanning was performed using a PP50 probe. Thirty-one sampling points were used, with a fixed strain of 1% and an angular frequency range of 0.1–100 rad / s. The storage modulus (G′), loss modulus (G″), and tanδ were recorded. The results are as follows: Figure 3 As shown.

[0097] Figure 3 The changes in G′ and G″ values ​​of starch pastes with angular frequency are shown. For all starch pastes, the G′ value is greater than the G″ value across the entire frequency range, indicating that all samples exhibit gel-like properties. When the frequency increases from 0.1 rad / s to 100 rad / s, the G′ and G″ values ​​of all samples increase, exhibiting weak gel-like properties. Figure 3 a) When starch gels are exposed to high frequencies, the starch chains cannot immediately rearrange; therefore, the gel exhibits solid rigidity, leading to an increase in G′ and G″ values. Furthermore, samples containing gelatin have higher G′ and G″ values ​​than pure starch paste. The loss factor (tanδ), defined as the ratio of G″ to G′, is commonly used to characterize the damping properties of a sample. The tanδ of all samples is greater than 0.1 but less than 1. Figure 3 (b) This also proves that the hydrogel is a weak gel. The tanδ value of the starch gel containing gelatin is lower than that of the pure starch gel, indicating that the composite gel has better gelling properties.

[0098] Example 6

[0099] This example compares the quality of different potato starch sheets.

[0100] Potato starch sheets were prepared using the methods provided in Examples 1-3 and Comparative Example 1, and are denoted as PSGN. 90:10 PSGN 85:15 PSGN 80:20 and PSGN 95:5 Bean curd sheets made from pure potato starch (PSGN) 100:0 () and starch sheets prepared from pure gelatin (GN) were used as controls.

[0101] Each sample was repeated three times. Data analysis was performed using SPSS 25 software (SPSS Inc., Chicago, IL). Differences were statistically significant at the 95% level (P < 0.05).

[0102] 1. Steaming and cooking characteristics of potato starch sheets

[0103] Weighing PSGN 90:10 PSGN 85:15 PSGN 80:20 PSGN 95:5 PSGN 100:0 10g each of GN (m0) and GN were placed in 350mL of boiling water and boiled until the optimal rehydration time was reached. The optimal rehydration time was when the rice noodle sheet was pressed with a glass plate until there was no hard core. After cooking, the rice noodle sheet was cooled to room temperature in cold water, the surface water was drained, and it was weighed and recorded as m1. The residue in the water was dried in an oven at 105℃ and recorded as m2. The rehydration rate and cooking loss rate were calculated using equations (1) and (2).

[0104] Water absorption rate (%) = m1 / m0 × 100 (1)

[0105] Cooking loss (%) = m2 / m0 × 100 (2)

[0106] Table 3. Cooking performance of different potato starch sheets

[0107]

[0108] Note: Data are expressed as mean ± standard deviation (n=3). The means of different letters (ae) in the same column are significantly different (p<0.05).

[0109] Table 2 shows that the rehydration time of dried starch sheets significantly decreases with increasing gelatin concentration. (Compared to PSGN) 100:0 In comparison, the rehydration time of dry starch skin containing 20% ​​gelatin was 11.75 ± 0.18 min (PSGN). 100:0 The time was shortened to 5.33 ± 0.17 min (PSGN) 80:20 The volume decreased by 54.64%. This is because gelatin has foaming properties; when mixed with potato starch, a large amount of air is introduced into the solution, creating numerous pores on the starch surface and inside, which accelerates the rehydration process. The rice noodles further expand after rehydration in the cooking water. Some potato starch and gelatin can leach out, making the structure even more porous. To confirm this, the transparency of the water after cooking was measured. Figure 4 As can be seen, the solution gradually becomes cloudy and opaque as the amount of gelatin added increases.

[0110] The cooking loss of rice noodles is mainly due to the dissolution of loosely bound gelatinized starch and gelatin. When the gelatin content is less than 15%, the cooking loss remains essentially unchanged, decreasing from 4.25% (PSGN). 100:0 It increased slightly to 5.43% (PSGN) 85:15 For the PSGN80:20 sample, the cooking loss increased to 8.54%, indicating that excessive gelatin addition led to a more open overall structure, causing gelatin to leach out during cooking. The rehydration rate also decreased with increasing gelatin content.

[0111] 2. Stretch properties of rehydrated potato starch sheets

[0112] All potato starch sheets were tested at the optimal cooking time. Following the method of QJSun, Chu, Xiong, and Si (2015), the tensile properties of flat noodles with different gelatin contents were measured using a texture analyzer equipped with an a / TGP probe (TA, XT Plus, Stable Micro Systems, Surrey, UK). The speeds before, during, and after the test were 3, 2, and 3 mm / s, respectively. The probe distance was 10 mm. The stress-strain curves of the potato starch sheets were obtained. All experiments were completed within 10 min after rehydration of the dried potato starch sheets. The results are as follows: Figure 5 As shown.

[0113] Texture is one of the important quality characteristics that determines the edible quality of potato starch sheets. The stress-strain curve of potato starch sheets under the optimal steaming time is shown below. Figure 5 As shown, potato starch sheets exhibit excellent tensile properties, with a strain of 429.66% and a stress of 0.27 MPa. After adding gelatin, the tensile stress of the potato starch sheets ranged from 0.17 to 0.33 MPa, and the strain ranged from 320.46% to 420.06%, indicating that the addition of gelatin had little effect on the tensile properties of the potato starch sheets. Replacing part of the potato starch with gelatin in the production of starch sheets weakens the original gel network due to the reduced starch concentration, leading to a decline in the texture properties of the starch sheets. When the gelatin concentration exceeds 10%, the tensile strain of the starch sheets begins to increase. Gelatin interacts with starch through hydrogen bonds, replacing the hydrogen bonds between starch molecules, allowing the starch molecular chains to slide freely, thereby enhancing their scalability. In conclusion, PSGN... 85:15 It also has good tensile properties while ensuring a short rehydration time (5.83±0.21min).

[0114] 3. Low-field nuclear magnetic resonance imaging of potato starch sheets

[0115] The transverse relaxation time (T2) of dried potato starch skin was analyzed using a low-field nuclear magnetic resonance (NMR) analyzer (Suzhou Niumai Analytical Instruments Co., Ltd.). Equal masses of potato starch skin were placed in 25 mm diameter NMR tubes for measurement. The following parameters were obtained using MultiExp Inv Analysis software (Suzhou Niumai Analytical Instruments Co., Ltd.): T2 includes T... 2b and T 21 And the corresponding area fraction PT 2b and PT 21 The results are shown in Table 4 and Figure 6 As shown.

[0116] Table 4. Changes in relaxation time and peak area ratio of different potato starch sheets

[0117]

[0118] Note: Data are expressed as mean ± standard deviation (n=3). The means of different letters (ad) in the same column are significantly different (p<0.05).

[0119] Figure 6 The transverse relaxation time (T2) spectral distribution of potato starch skin containing gelatin is shown. The T2 relaxation time reflects the chemical environment of hydrogen protons within the dried potato starch skin and is related to the binding force and degrees of freedom of the hydrogen protons. The greater the binding force or the smaller the degrees of freedom of the hydrogen protons, the shorter the T2 relaxation time, and the more the upper peak of the T2 spectrum shifts to the left.

[0120] All powder foundations exhibit two peaks. Based on the relaxation time of these peaks, relaxation times ranging from 0.1 to 10 ms are categorized as bound water (T0). 2b The relaxation time of 10-100 ms is classified as constant water (T). 21 ). with PSGN 100:0 In comparison, T in gelatin powder skin 2b and T 21 The peaks all shifted to the left (Table 4), T 2b The peak value was 4.20 ± 0.02 ms (PSGN). 100:0 The time to move to 1.59±0.07ms (PSGN) 80:20 ), T 21 The peak value was 51.31 ± 0.63 ms (PSGN). 100:0 The time was 41.50 ± 0.16 ms (PSGN) 85:15 This indicates that the addition of gelatin allows water molecules to bind more tightly to both components of the system, reducing water fluidity. Due to gelatin's strong water absorption, its addition promotes water molecule penetration, thereby increasing its binding capacity with water. Furthermore, PT... 2b From 0.960±0.002 (PSGN)100:0 The value decreased to 0.931 ± 0.006 (PSGN). 80:20 ), PT 21 From 0.040±0.002 (PSGN) 100:0 The value increased to 0.069 ± 0.006 (PSGN). 80:20 This indicates that the addition of gelatin altered the moisture distribution in the system, leading to a decrease in the interaction ability between starch and water molecules.

[0121] 4. Scanning electron microscope (SEM) of potato starch sheets

[0122] The dried potato starch sheets were coated with gold on both the surface and cross-section. The microstructure of dried potato starch sheets with different gelatin contents was observed using an S-4800 scanning electron microscope (Hitachi Instruments Ltd, Tokyo, Japan) at an accelerating voltage of 2 kV. The results are as follows: Figure 7 As shown.

[0123] Figure 7 The microstructure of the surface and cross-section of dried potato starch sheets before rehydration is shown, which relates to the cooking properties of gelatin-containing starch sheets. PSGN 100:0 Its surface and cross-sectional structure are relatively flat and compact, with almost no visible holes. (Compared to PSGN) 100:0 In contrast, gelatin-based noodle sheets have noticeable pores on their surface and cross-section, with pore sizes ranging from 40 to 200 μm. Furthermore, the number of pores in the noodle sheet increases with increasing gelatin content. This porous structure creates a larger surface area, allowing water to penetrate more quickly into the center of the noodle, thus shortening the rehydration time of the dried noodle sheet during cooking. The porous structure created by adding gelatin to the noodle sheet helps to shorten the rehydration time.

[0124] 5. Thermal properties of dried potato starch sheets

[0125] Dried potato starch and luminescent adhesive powder (4 mg, dry basis) were accurately weighed and sealed in an aluminum pot with 8 μL of ultrapure water. The samples were equilibrated at 25 °C for 12 h, using an empty crucible as a reference. The initial temperature (To), peak temperature (Tp), final temperature (Tc), and enthalpy (ΔH) of each sample were obtained using differential scanning calorimetry (Mettler Toledo, Schwerzenbach, Switzerland) at a rate of 10 °C / min from 25 °C to 125 °C in nitrogen. The results are shown in Table 5 and... Figure 8 As shown.

[0126] Table 5 Thermal properties of different potato starch sheets and gelatin sheets

[0127]

[0128] Note: Data are expressed as mean ± standard deviation (n=3). Mean differences between different letters (ad) within the same column are statistically significant (p<0.05). ND indicates not detected.

[0129] Figure 8 Table 6 shows the gelatinization characteristics of dried potato starch sheets with different levels of gelatin. PSGN 100:0 The To, Tp, and Tc values ​​were 52.23±0.06℃, 60.09±0.38℃, and 72.40±0.40℃, respectively, with no significant difference in gelatinization temperature between potato starch sheets with and without gelatin. However, the Tp of gelatin (35.46±0.02℃) was much lower than that of potato starch (60.09±0.38℃), forming a two-phase endothermic peak. Endothermic peak 1 near 30-44℃ is caused by the triple helix dissociation of gelatin, and its peak area increases with the increase of gelatin addition. Endothermic peak 2 near 50-74℃ corresponds to the melting of starch in the dried potato starch sheets.

[0130] The ΔH value represents the enthalpy of fusion of the crystal. As can be seen from the results in Table 5, ΔH1 increases with increasing gelatin concentration, from 0.34 ± 0.04 J·g. -1 (PSGN 95:5 The concentration increased to 2.52 ± 0.03 J·g. -1 (PSGN 80:20 This is predictable. ΔH2 corresponds to the enthalpy change of starch in potato starch sheets; the addition of gelatin caused ΔH2 to change from 2.13 ± 0.03 J·g. -1 (PSGN 100:0 Increased to 3.00±0.12 J·g -1 (PSGN 90:10 This indicates that the potato starch sheets prepared by this invention improve the crystallinity of the sheets. The ΔH2 value varies depending on the gelatin content of the dried potato starch sheets. When the gelatin content exceeds 10%, ΔH2 changes from 3.00 ± 0.12 J·g. -1 (PSGN 90:10 The concentration decreased to 2.73 ± 0.05 J·g. -1 (PSGN 80:20 This indicates that the interaction between gelatin and starch hinders the formation of starch crystal structure.

[0131] 6. Crystalline structure and long-range ordered structure of dried potato starch sheets

[0132] Dried potato starch sheets and luminescent gum sheets were ground, sieved through a 100-mesh sieve, and their moisture content was adjusted to 20%. The mixture was then equilibrated at 25°C for at least 12 hours. Diffraction patterns were recorded using an X-ray diffractometer (AxSD8 Advance, Bruker, Karlsruhe, Germany) under CuKα radiation (25mA, 40kV) in the 4°–40° scanning range. The formula for calculating relative crystallinity (RC) is as follows:

[0133] RC(%)=[A c / (A c +A α ]×100 (3)

[0134] from Figure 9 It can be seen that GN has a bare peak at 20.85°, indicating that gelatin is an amorphous substance. Native potato starch has a typical b-type crystal structure, with peak values ​​at 2θ of 5.6°, 17.1°, 22.0°, and 24.0°. PSGN 100:0 The diffraction peak mainly appears at 17.1°, with a crystallinity of 11.45%. According to the diffraction pattern of the gelatin-containing potato starch sheet, three diffraction peaks can be observed at 5.6°, 17.1°, and 22.0°, corresponding to the characteristic peaks of the type b structure of potato starch. The presence of type b crystals in dried potato starch sheet containing gelatin is mainly because the presence of gelatin promotes the reconstruction of the double helix structure of starch during cooling and drying.

[0135] According to the results in Table 6, the addition of gelatin reduced the relative crystallinity of the rice noodle sheet from 11.64 ± 0.18 (PSGN). 100:0 The value increased to 19.72 ± 0.21 (PSGN). 90:10 This indicates that gelatin can promote the recrystallization of dried potato starch skin, which is consistent with the increase in the retrogradation value of RVA. However, because hydrogen bonds are formed between gelatin and starch, the formation of hydrogen bonds between starches is weakened, thus preventing the recrystallization of dried potato starch skin at 45°C. When the amount of gelatin added is greater than 10%, the crystallinity of the sample decreases from 19.72% ± 0.21 (PSGN). 90:10 (PSGN) dropped to 15.80% 80:20 When the amount of gelatin added increased from 15% to 20%, the crystallinity of the rice noodle sheet began to decrease slowly. This indicates that when 20% gelatin is added to the rice noodle sheet, the hydrogen bonds formed between the gelatin and potato starch gradually become saturated.

[0136] Table 6. Long-range ordered structures of different potato starch sheets

[0137]

[0138] Note: Data are expressed as mean ± standard deviation (n=3). The means of different letters (ad) in the same column are significantly different (p<0.05).

[0139] 7. Chemical structure and short-range ordered structure of dried potato starch sheets

[0140] Each sample was thoroughly mixed with potassium bromide (KBr) at a ratio of 1:100 (w / w), and the mixture was then compressed into thin sheets. The sheets were incubated against a KBr background at a depth of 400–4000 cm⁻¹. -1 64 scans were performed within the range, with a resolution of 4 cm. -1 The spectrum of the powder skin was obtained. The spectral density at 1047 cm⁻¹ was calculated. -1 / 1022cm -1 The absorbance was measured to compare the short-range order of starch in different types of rice noodle sheets.

[0141] Figure 10 The diagram shows that, for GN, typical spectral characteristics are located at 1650 cm⁻¹. -1 and 1540cm -1 The absorption of amide I and II bands is strong. Amide I absorption is mainly due to the stretching vibration of the C=O bond, while amide II absorption is mainly due to the coupling effect of the bending of the NH bond and the stretching of the CN bond. The presence of gelatin in potato starch sheets can be detected through 1540 cm⁻¹. -1 The characteristic peak was used to confirm that it is specific to gelatin. The peak gradually intensifies with increasing gelatin content. (3000-2800 cm⁻¹) -1 The band belongs to the CH tensile vibration region. At 3300 cm⁻¹ -1 The wavelength range has been shown to be associated with the OH-strained vibrations of starch molecules or the NH-strained vibrations of proteins, and the shift of the peak to lower wavelengths represents an enhancement of hydrogen bonds in the system. When the amount of gelatin added increased from 0% to 20%, this wavelength range shifted to lower wavelengths (from 3285 to 3277 cm⁻¹). -1 The presence of hydrogen bonds indicates an enhancement in the system. This is likely due to the hydrogen bond interaction between the hydroxyl groups on potato starch and the amino groups on gelatin, which promotes the formation of a unified structure between the gelatin and potato starch.

[0142] The short-range order of potato starch sheets can be estimated by calculating R1047 / 1022. (Except for PSGN) 80:20 In addition, the R1047 / 1022 values ​​(0.5385-0.5720) of potato starch sheets containing gelatin were all higher than those of PSGN. 100:0 (0.5385) indicates that the short-range order of potato starch sheets containing gelatin is improved. Figure 10 b).

[0143] 8. The lamellar structure and fractal characteristics of dried potato starch sheets

[0144] The supramolecular structure was tested using a small-angle X-ray scattering system (λ = 0.154 nm, Xenocs, Sassenage, France) according to a previous method (K. Liu, Zhang, Chen, Li, & Zheng, 2019). Powdered sheets with a moisture content of 85% were placed at equilibrium temperature of 25°C for 12 hours before testing. The test conditions were as follows: voltage 50 kV, current 0.6 mA, two scans, and a detection time of 5 min to obtain the signal intensity of the sample. The two-dimensional data were converted to one-dimensional data, and the scattering curves were analyzed.

[0145]

[0146] In the formula, x is the distance in actual space, I(q) is the scattering intensity, and q is the scattering vector.

[0147] The fractal structure of the bean curd sheet is determined by a power-law equation:

[0148] I(q)~q -α (5)

[0149] Where α represents the slope of the double logarithmic SAXS curve in the low q range.

[0150] The lamellar structure and fractal characteristics of dried potato starch skin were further analyzed using SASX (small-angle X-ray scattering). Figure 11 As shown in Table 6, characteristic peaks can be observed in the range of 0.1–0.3 nm. By calculating D = 2π / q, the Bragg length (D) of the potato starch sheet can be determined to correspond to 23.891–33.410 nm. This represents the average total thickness of the crystalline and amorphous layered regions in the layered structure of potato starch. Multiplying the ordinate by q... 2 Make the scattering peaks clearer. Figure 11 b). It was observed that as the gelatin concentration increased, the scattering peak shifted to the lower q region, indicating that the average total thickness of the layered structure inside the potato starch skin increased.

[0151] Furthermore, to investigate the structural density of potato starch sheets, the fractal structure of the sheets was further analyzed. The α values ​​of all sheets were between 1 and 3, indicating that the dispersion exhibited a mass fractal structure, with the mass fractal dimension Dm = -α representing its density. With increasing gelatin concentration, the α value increased from 1.769 (PSGN). 100:0 Reduced to 1.308 (PSGN) 80:20 This indicates that the addition of gelatin loosens the structure of starch aggregates, which facilitates the rapid rehydration of potato starch sheets.

[0152] Example 7

[0153] This embodiment compares the rehydration properties of potato starch sheets with different proportions.

[0154] Potato starch sheets were prepared using the methods provided in Example 1 and Comparative Example 1, with sheets prepared from pure potato starch serving as a control. 10g of each sheet was weighed and placed in 350mL of boiling water to the optimal rehydration time. The optimal rehydration time was determined by pressing the sheet with a glass plate until no hard core remained. The results are shown in Table 7.

[0155] Table 7 Rehydration Time of Potato Starch Sheets Containing Different Types of Protein

[0156]

[0157] Note: Data are expressed as mean ± standard deviation (n=3). The means of different letters (ad) in the same column are significantly different (p<0.05).

[0158] As shown in Table 7, the potato starch sheet provided by this invention can significantly shorten the rehydration time.

[0159] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing potato noodles, characterized by, The method comprises the following steps: The gelatin is mixed with water to swell, then stirred to dissolve, mixed with potato starch, the mixed slurry is poured into a mold and steamed in boiling water, then cooled and dried to obtain potato starch noodles; the pore diameter of the potato starch noodles is 40-200 μm; The mass ratio of the potato starch to the gelatin is 90:10-85:15; The mass ratio of the mixture of the gelatin and the potato starch to water is 6:9; The mixed gelatin is swelled for 15-40 min after mixed with water; The drying is performed at 40-55 ℃ for 3-5 h; The swelled gelatin is stirred at 40-55 ℃, and the stirring rate is 800-1500 rpm; The slurry is steamed in the mold for 3.5-5 min.

2. A potato powder characterized in that, The potato starch noodles are prepared by the preparation method in claim 1.

3. The potato pasta of claim 2, wherein, The moisture content of the potato starch noodles is 10-15%.

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