Method for improving reheating quality of refrigerated prefabricated noodles by combining compound colloid with modified atmosphere packaging

Abstract

The invention discloses a method for improving the reheating quality of refrigerated prefabricated noodles by combining compound colloid with modified atmosphere packaging, and belongs to the technical field of instant food processing. According to the invention, 0.03% of Sa-son seed gum and sunflower pectin compound colloids with different contents are added to prepare the prefabricated noodles, modified atmosphere packaging and refrigeration are combined, and the influence of the compound colloids and a packaging mode on the reheating quality of the prefabricated noodles after refrigeration is explored. Through a response surface test, the maximum tensile force after refrigeration is taken as a response value, and the optimal preparation process of the prefabricated noodles is determined as follows: the sunflower pectin addition amount is 0.35%, the water addition amount is 40%, and the dough kneading time is 15 minutes. When the prefabricated noodles optimized by the process are refrigerated for 7 days under modified atmosphere packaging, the sensory score of an optimal process group is 70.4, the microstructure is more compact, the breaking rate is only 20.0%, the maximum tensile force is 106.4 g, the hardness is 1888 g, the chewiness is 1241 g, the number is obviously higher than that of a control group, the total number of bacterial colonies does not exceed 104 and is obviously lower than that of the control group, and the quality of the prepared noodles is improved. Therefore, modified atmosphere packaging can be used as an optimal packaging mode for refrigeration of the prefabricated noodles.

Description

Technical Field

[0001] The invention belongs to the technical field of instant food processing, and in particular relates to a method for improving the reheating quality of refrigerated prefabricated noodles by utilizing compound colloid combined with modified atmosphere packaging. Background Art

[0002] During the refrigeration or freezing process, the prefabricated noodles will experience loose gluten network, water loss, starch aging and other phenomena, resulting in a decrease in quality. Adding hydrophilic colloids to the system is generally used to improve the water retention and texture characteristics of prefabricated noodles, and improve the quality after refrigeration and freeze-thaw. Studies have shown that 0.3% curdlan gum or 0.6% xanthan gum can delay the evaporation of water in prefabricated noodles during refrigeration, increase water holding capacity, and improve its texture characteristics; adding 1.2% trisammonium gum can slow down the salt-free frozen cooked noodles to inhibit the recrystallization of water and the breaking of disulfide bonds, and improve freeze-thaw stability. Artemisia Sphaerocephala Krasch Gum (ASKG) is a hydrophilic colloid with good water absorption and swelling properties, and is widely used in different food formulations, such as thickeners, stabilizers and water retaining agents. Studies have shown that 0.1% to 0.5% ASKG can enhance the texture properties by improving the network structure of potato starch paste; ASKG can form a stable cross-linked structure with gluten protein, protect gluten protein during -18℃ freezing, and make the gluten network more compact; in addition, ASKG can inhibit the aging of starch during 4℃ refrigeration. However, GB 2760-2014 "National Food Safety Standard for the Use of Food Additives" stipulates that the amount of ASKG added to flour products shall not exceed 0.3g / kg, which cannot achieve the desired effect. Sunflower pectin (SP) is a low-cost, highly safe, and widely sourced hydrophilic colloid that has been widely used in the food industry as a thickener, gelling agent, etc. Adding SP to Cantonese sausage can reduce water migration during room temperature storage and improve water retention.

[0003] The compound colloids with appropriate proportions can better protect the gluten network structure and starch integrity, reduce the migration of various water, and the compounding of 0.25% xanthan gum, 0.21% carrageenan, 0.28% konjac gum and 0.39% guar gum has a synergistic effect, which significantly improves the sensory quality of quick-frozen dumplings; konjac gum and ASKG compounded in a ratio of 8:2 can make the network structure of the compound gel more compact, improve hardness, adhesion and elasticity; adding 0.7% ASKG and 0.3% sodium polyacrylate compound colloids to wet potato noodles can form hydrogen bonds with starch and improve the stability of the system. However, there is still a blank in the research on the improvement of the reheating quality of pre-made noodles after refrigeration by SP compounding ASKG. In addition, in order to extend the shelf life, vacuum packaging, modified atmosphere packaging and other technologies are widely used in fresh and fried foods, while there are few related studies on pre-made noodles.

[0004] Based on the above reasons, this application is hereby filed. Summary of the invention

[0005] In view of the problems or defects of the above-mentioned prior art, the purpose of the present invention is to provide a method for improving the reheating quality of refrigerated prefabricated noodles by using compound colloids combined with modified atmosphere packaging. The present invention adds 0.03% ASKG and SP compound colloids of different proportions to prefabricated noodles, takes the maximum tensile force as the response value, and optimizes the process parameters of prefabricated noodles such as SP addition amount, water addition amount, and dough mixing time through response surface test; heat sealing (HS), vacuum packaging (VP) and modified atmosphere packaging (MP) are selected to package and refrigerate the prefabricated noodles, and the effects of compound colloids and packaging methods on the reheating quality of prefabricated noodles such as sensory quality, microstructure, cooking characteristics, and texture characteristics within 7 days of refrigeration are explored, so as to provide a theoretical basis for further improving the quality of prefabricated noodles.

[0006] In order to achieve the above-mentioned purpose of the present invention, the technical solution adopted by the present invention is as follows:

[0007] A method for improving the reheating quality of refrigerated prefabricated noodles by using a compound colloid combined with modified atmosphere packaging, comprising the following steps:

[0008] Artemisia gum, sunflower pectin and sodium chloride are added to water in sequence according to a proportion, mixed evenly, and an additive solution is obtained; the additive solution is then mixed with flour, the dough is kneaded and left to rise, pressed into sheets to form noodles, cooked, packaged in an atmosphere-controlled manner, and then refrigerated.

[0009] Further, in the above technical solution, the wormwood glue is prepared from wormwood seeds, and the specific method is as follows:

[0010] The wormwood seeds are mixed with water according to a ratio, and after heating, they are subjected to ultrasound, high-speed stirring and centrifugation in sequence to obtain an intermediate layer of emulsion colloid, and the wormwood seeds in the colloid are removed, freeze-dried and crushed to obtain the wormwood glue.

[0011] Preferably, in the above technical solution, the mass ratio of the Artemisia ordosica seeds to water is 1:60.

[0012] Preferably, in the above technical solution, the heating temperature is 55-65° C., and the heating time is 1.5-2.5 h.

[0013] Preferably, in the above technical solution, the rotation speed of the high-speed stirring is 400-450 rpm, and the stirring time is 25-35 min.

[0014] Furthermore, in the above technical solution, the mass ratio of the artemisia gum to flour is 0.03:100.

[0015] Furthermore, in the above technical solution, the mass ratio of sunflower pectin to flour is 0.3-0.9:100.

[0016] Preferably, in the above technical solution, the mass ratio of sunflower pectin to flour is 0.3-0.6:100.

[0017] More preferably, in the above technical solution, the mass ratio of sunflower pectin to flour is 0.35:100.

[0018] Furthermore, in the above technical solution, the mass ratio of sodium chloride to flour is 1:100.

[0019] Furthermore, in the above technical solution, the mass ratio of water to flour is 35-45:100.

[0020] Preferably, in the above technical solution, the mass ratio of water to flour is 40:100.

[0021] Furthermore, in the above technical solution, the time for kneading the dough is 5-20 minutes.

[0022] Preferably, in the above technical solution, the kneading time is 10-20 minutes.

[0023] More preferably, in the above technical solution, the kneading time is 15 minutes.

[0024] Furthermore, in the above technical solution, the proofing time is 25-40 minutes.

[0025] Preferably, in the above technical solution, the proofing time is 30 minutes.

[0026] Furthermore, in the above technical solution, the flour is high-gluten flour.

[0027] Furthermore, in the above technical solution, the gas in the modified atmosphere packaging consists of 60% CO2 and 40% N2.

[0028] Furthermore, in the above technical solution, the material used for the modified atmosphere packaging is PA / PE.

[0029] Furthermore, in the above technical solution, the refrigeration time does not exceed 7 days.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention adds different amounts of sunflower pectin and 0.03% wormwood gum to a compound colloid, and combines gas conditioning and vacuum packaging for 7 days of refrigeration to explore the effects of compound colloid and packaging methods on the reheating quality of prefabricated noodles after refrigeration. The optimal process parameters are determined by response surface experiment: 40% water addition, 0.35% sunflower pectin addition, and 15 minutes of dough mixing time. The prefabricated noodles after process optimization are refrigerated in vacuum and gas conditioning packaging, respectively. It is found that vacuum packaging seriously damages the gluten network of the prefabricated noodles, making the sensory quality after reheating lower than that of other groups, and the cooking loss rate and broken rate are significantly increased (P<0.05), and the tensile and texture characteristics are significantly decreased (P<0.05). The network structure of the prefabricated noodles under gas conditioning packaging is more complete, the sensory quality is higher, the cooking loss rate and broken rate are significantly decreased (P<0.05), the tensile and texture characteristics are higher than other groups, and it has a good antibacterial effect, so it can be used as the best packaging method for refrigeration of prefabricated noodles. In addition, the prefabricated noodles with the addition of compound colloids showed a denser gluten network structure, improved water holding capacity, inhibited starch aging to a certain extent, significantly improved the sensory quality after refrigeration and reheating (P<0.05), significantly increased water absorption (P<0.05), significantly reduced cooking loss rate and broken rate (P<0.05), and improved tensile and texture properties. This study provides some references for exploring the packaging methods of prefabricated noodles and the influence mechanism of compound hydrophilic colloids on prefabricated noodles. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 : Effects of SP addition amount (A), water addition amount (B), dough mixing time (C), and proofing time (D) on the maximum tensile force and sensory scores of pre-made noodles reheated after refrigeration.

[0033] Figure 2 (a), (b), and (c) respectively show the effects of the interaction of different factors on the maximum tensile force.

[0034] Figure 3 :Actual pictures of samples at each stage.

[0035] Figure 4:Changes in sensory scores of pre-made noodles after reheating in different packaging methods with storage time; Note: Different lowercase letters indicate significant differences in the same experimental group and different storage times (P<0.05); Different uppercase letters indicate significant differences in different experimental groups and the same storage time (P<0.05).

[0036] Figure 5 Changes in the microstructure of pre-made noodles after reheating in different packaging methods with storage time (500×).

[0037] Figure 6 Changes in cooking characteristics of pre-made noodles after reheating in different packaging methods with storage time.

[0038] Figure 7 Changes in total colony count of pre-made noodles in different packaging methods over storage time. DETAILED DESCRIPTION

[0039] The present invention is further described in detail below through implementation cases. This implementation case is implemented based on the technology of the present invention, and a detailed implementation method and specific operation process are now given to illustrate that the present invention is creative, but the protection scope of the present invention is not limited to the following implementation cases.

[0040] Based on the information contained in this application, it is easy for those skilled in the art to make various changes to the precise description of the present invention without departing from the spirit and scope of the appended claims. It should be understood that the scope of the present invention is not limited to the defined process, properties or components, because these embodiments and other descriptions are only for illustrating specific aspects of the present invention. In fact, various changes that the technicians in this field or related fields can obviously make to the embodiments of the present invention are all covered within the scope of the appended claims.

[0041] In order to better understand the present invention but not to limit the scope of the present invention, all the numbers used in this application to express the amount, percentage, and other numerical values ​​should be understood as modified by the word "about" in all cases. Therefore, unless otherwise specified, the numerical parameters listed in the specification and the appended claims are approximate values, which may be changed according to the different ideal properties attempted to be obtained. Each numerical parameter should at least be regarded as obtained based on the reported significant figures and by conventional rounding methods.

[0042] The materials and reagents used in the following examples, unless otherwise specified, can be obtained from commercial sources. For example, the sunflower pectin CSP855-Y used in the following examples was purchased from Inner Mongolia Kangster Biotechnology Co., Ltd.; Artemisia ordosus seeds were purchased from Dongwayao Wholesale Market, Saihan District, Hohhot, Inner Mongolia; high-gluten wheat flour was purchased from Shanghai Yihai Kerry Food Marketing Co., Ltd.; sodium chloride was purchased from Sinopharm Chemical Reagent Co., Ltd.; PCA culture medium was purchased from Qingdao Haibo Biotechnology Co., Ltd.

[0043] Example 1

[0044] A method of improving the reheating quality of refrigerated prefabricated noodles by using a compound colloid combined with modified atmosphere packaging in this embodiment comprises the following steps:

[0045] (1) Preparation of Artemisia sphaerocephala glue

[0046] Weigh 20g of Artemisia sphaerocephala seeds and mix them with water in a mass ratio of 1:60, heat them in a 60℃ water bath for 2h, and then ultrasonically treat them for 10min; place the mixture under a high-speed stirrer, set the speed to 400-450rpm, and the time for 30min; centrifuge it in a high-speed centrifuge for 10min, the speed is 8000rpm, and the temperature is -15℃; take the middle layer of emulsion colloid and spread it on a plate, pick out the Artemisia sphaerocephala seeds, freeze-dry them for more than 24h, take out the sample and crush it for later use;

[0047] (2) Production of pre-made noodles

[0048] A certain mass of high-gluten wheat flour was weighed, 0.03wt% of artemisia gum, sunflower pectin and 1.0wt% of sodium chloride were added to water, the flour was poured in after thorough mixing, the dough was kneaded with a dough mixer and then allowed to stand, and the noodles (5mm wide and 1.5mm thick) were sheeted and heated in a pot with an induction cooker with 500mL of distilled water. After the water boiled, the noodles were added and cooked for 3min, then put into a ziplock bag, refrigerated for 3 days, and then boiled for 90s for testing.

[0049] Single factor experiment

[0050] The effects of water addition amount (35, 40, 45 and 50wt%), SP addition amount (0, 0.3, 0.6 and 0.9wt%), mixing time (5, 10, 15 and 20min) and proofing time (25, 30, 35 and 40min) on the tensile properties and sensory scores of prefabricated noodles after re-cooking were investigated to determine the optimal indicators for each condition.

[0051] Response Surface Optimization Experimental Design

[0052] Based on the above single-factor experimental results, three factors, namely, water addition, SP addition, and dough kneading time, were selected as independent variables. The independent variables and level designs are shown in Table 1. With the maximum tensile force as the response value, a three-factor three-level experimental design was performed according to the Box-Behnken experimental design principle. Data processing and analysis were performed to determine the optimal process parameters. The maximum tensile force was repeatedly measured under the optimized conditions to verify accuracy and stability.

[0053] Table 1 Factors and levels of response surface experiment

[0054]

[0055] Experiment on packaging and storage of pre-made noodles

[0056] The prefabricated noodles prepared by the optimization results obtained by the above response surface optimization test design were named OP group, and the control group (CK) without adding compound colloid was used. The prefabricated noodles were prepared according to the above prefabricated noodles production method, and heat-sealed (HS), vacuum packaged (VP), and modified atmosphere packaged (MP) were respectively performed, and named CK-HS, OP-HS, CK-VP, OP-VP, CK-MP, and OP-MP. Among them, the materials of the above packaging were all PA / PE, and the ratio of modified atmosphere was 60% CO2 and 40% N2. After refrigeration at 4°C for 0, 3, 5, and 7 days, the noodles were reheated and the following indicators were tested.

[0057] Sensory Rating

[0058] The sensory evaluation was conducted in the sensory evaluation laboratory by 10 professionally trained sensory evaluators, and the scoring criteria were referred to Table 2.

[0059] Table 2 Sensory evaluation score table for pre-made noodles

[0060]

[0061] Microstructure (SEM)

[0062] After the sample was freeze-dried, it was fixed to the sample stage with a conductive double-sided tape and observed under a scanning electron microscope at a magnification of 500×, with an acceleration voltage of 15 kV.

[0063] Cooking characteristics

[0064] Boil 15 raw noodles in a pot, record the number of breaks (n), and calculate the breakage rate according to equation (1). Rinse the reheated pre-made noodles slowly in pure water for 10 seconds, pour the rinse water into the pot, heat until most of the water evaporates, transfer to a beaker and dry, weigh the dry material (A2), and calculate the cooking loss rate according to (2). Let the rinsed pre-made noodles stand for 2 minutes, weigh (A3), and calculate the water absorption rate according to equation (3).

[0065]

[0066] Where n is the number of cooked noodles that are broken after cooking; A1 is the mass of raw noodles, g; A2 is the weight of dry material, g; A3 is the mass of cooked noodles after cooking, g.

[0067] Tensile and texture properties

[0068] The noodles were immediately taken out after re-cooking and rinsed with pure water to drain the excess water. Then, the residual water on the surface of the noodles was further absorbed with filter paper. The tensile and texture properties of the noodles were determined using a texture analyzer. The test was completed within 30 minutes after the noodles were re-cooked.

[0069] Tensile characteristics: Cut a 10cm length, wrap it around a probe rod, use A / SPR probe, set the spacing to 20mm, the pre-measurement speed to 1.00mm / s, the measurement speed to 3.00mm / s, the post-measurement speed to 10.00mm / s, and the trigger force to 5.0g.

[0070] Texture characteristics: The probe used is P60 type, the spacing is set to 25mm, the speed before the test is 2mm / s, the speed during the test is 1mm / s, the speed after the test is 2mm / s, the deformation is 50%, the trigger force is 5.0g, and the time interval is 1s. In each test, 3 noodles are placed vertically on the loading platform.

[0071] Total colony count

[0072] After the prepared noodles were refrigerated for 0, 3, 5 and 7 days, the total number of colonies was determined according to GB 4789.2-2022 "Determination of the total number of colonies in food microbiological examination". TCCA024-2022 "Prepared Dishes" stipulates that the acceptable limit of the total number of colonies in preprepared noodles is 10 4 CFU / g, the maximum safety limit is 10 5 CFU / g.

[0073] Data analysis

[0074] All experiments were repeated at least 3 times, and SPSS27.0 and Origin 2022 were used for statistical analysis and graph drawing, and Duncan test was used for significance analysis, with P < 0.05 as a significant difference. Design-Expert 13 was used for response surface method optimization analysis.

[0075] Results and Analysis

[0076] Single factor experiment results

[0077] Effects of SP addition on tensile properties and sensory scores of prefabricated noodles

[0078] like Figure 1 A. Compared with the group with only ASKG, the tensile properties of noodles were significantly improved after adding SP (P<0.05). The maximum tensile force showed a trend of first increasing and then decreasing with the increase of SP addition, reaching a maximum value of 115.2g when the addition amount was 0.3wt%. This is because SP and ASKG interact with gluten protein, making the network structure denser; however, excessive addition of SP will aggravate the phenomenon of hydrophilic colloid competition for water in the system, and the increase in the content of polysaccharide macromolecules will make gluten protein relatively loose, resulting in changes in the network structure. Sensory evaluation can directly reflect people's satisfaction and acceptance of noodle quality. The effect of SP addition on sensory scores is similar to that of tensile properties, indicating that the above phenomenon will also affect sensory quality.

[0079] Effects of water addition on tensile properties and sensory scores of prefabricated noodles

[0080] like Figure 1 B. The maximum tensile force and sensory score showed a trend of first increasing and then decreasing with the increase of water addition, reaching a maximum value of 95.8g when the water addition was 40%. This is because too much or too little water addition is not conducive to the formation of the gluten network. 40% water addition increases the disulfide bond content in the gluten, which is beneficial to the formation of the gluten network, thereby helping to improve the texture, tensile properties and other properties.

[0081] Effects of dough mixing time on tensile properties and sensory scores of pre-made noodles

[0082] like Figure 1 C. The maximum tensile force increases first and then decreases with the increase of dough mixing time, reaching a maximum value of 119.9g at 15 minutes, and the sensory score also shows the same trend. This is because as the dough mixing time increases, the moisture distribution in the dough gradually becomes uniform, which helps the formation of the gluten network; when the dough is mixed for 20 minutes, the tensile force decreases, which is because the long dough mixing time destroys the formed gluten network.

[0083] Effects of fermentation time on tensile properties and sensory scores of prefabricated noodles

[0084] like Figure 1 D. The effect of the fermentation time on the tensile properties and sensory scores of noodles was not significant (P>0.05). When the fermentation time was 30 minutes, the gluten protein and water molecules were more tightly bound, and the gluten network structure was more stable; when the fermentation time was more than 30 minutes, the gluten, starch and water were more stable, and there was no significant difference in properties, which also had no significant effect on the sensory quality. The fermentation time had the least effect on the system, so it was not considered as a factor in the response surface experiment.

[0085] Optimization results of response surface experiment on processing technology of prefabricated noodles

[0086] According to the results of the single factor test, the Design-Expert software was used, with the amount of water added (A), the amount of SP added (B), and the dough mixing time (C) as the response surface test factors, and the maximum tensile force (Y) as the evaluation index. The response surface test results are shown in Table 3.

[0087] The experimental data in Table 3 were fitted with multiple regression using Design-Expert 13 statistical software, and the quadratic multinomial regression model of the maximum tensile force (g) on ​​the three factors of water addition (A), SP addition (B), and dough mixing time (C) was obtained: Y = 117.48-1.46A+4.34B+0.40C-0.65AB-3.63AC-1.83BC-16.54A 2 -15.34B 2 -23.13C 2 .

[0088] Table 3 Box-Behnken experimental design and results

[0089]

[0090]

[0091] Model variance analysis and response surface analysis

[0092] Table 4 Analysis of variance of regression model

[0093]

[0094] Note: * indicates significant difference (P<0.05); ** indicates extremely significant difference (P<0.01).

[0095] The analysis and results of the regression model are shown in Table 4. The quadratic multinomial regression equation model established with the maximum tensile force as the response value is extremely significant (P<0.0001), and the lack of fit term of the fitting equation is not significant (P>0.05), indicating that the regression model fits the response value well; the determination coefficient R 2 =0.9816, good correlation; Corrected determination coefficient R 2 Adj =0.9580, coefficient of variation CV% <5%, indicating that the experiment has high precision and accuracy, and the model has high credibility; the signal-to-noise ratio of the model is >4, which shows that the model can be used to determine the optimal process parameters for prefabricated noodles. Comparing the size of the F value, it can be seen that the order of factors affecting the maximum tensile force of prefabricated noodles after refrigeration and reheating is B (SP addition amount) > A (water addition amount) > C (dough mixing time); from the P value, it can be seen that B has a significant effect on the maximum tensile force (P < 0.05); A 2 , B 2 , C 2The effect on the maximum tensile force was extremely significant (P<0.01).

[0096] The response surface and contour lines of the interaction between factors on the maximum tensile force are shown in Figure 2. Figure 2 As shown in the figure. The more curved the surface in the response surface diagram, the greater the influence of the research factors on the results. It can be seen that the interaction between the amount of water added and the dough mixing time is relatively obvious, indicating that these two factors can more effectively affect the formation of the gluten network structure. The appropriate dough mixing time can make the water mix more evenly without destroying the already formed system structure. However, there is no obvious interaction between the amount of SP added and the amount of water added and the dough mixing time (P>0.05).

[0097] The optimal process for pre-made noodles was predicted by Design-Expert 13 as follows: water addition 39.76%, SP addition 0.34%, and dough mixing time 15.04 min. Considering the actual operation problems, the process parameters were adjusted to: water addition 40%, SP addition 0.35%, and dough mixing time 15 min. Three parallel experiments were conducted under this condition, and the maximum tensile force was measured to be 115.7 ± 3.4 g, with a relative error of 1.90% with the model prediction value, indicating that the optimized process parameters are highly reliable.

[0098] Effect of packaging methods on sensory scores of pre-prepared noodles after refrigeration and reheating

[0099] exist Figure 4 The sensory scores of each experimental group decreased with the extension of storage time; the sensory quality of the CK-VP and OP-VP groups was lower than that of the other groups at each storage period. This may be due to the excessive pressure of the vacuum on the prefabricated noodles, which destroyed the original texture characteristics of the noodles. Figure 3 The actual pictures presented also reflect this phenomenon; on the 7th day, the sensory scores of the CK-MP and OP-MP groups were 70.8 and 70.4, respectively, both higher than those of the other groups, indicating that MP is more conducive to the storage and preservation of prefabricated noodles. Figure 3 and 4 It can be found that the sensory quality of OP-MP during the refrigeration process is higher than that of CK-MP. This is because the compound colloid is hydrophilic and thickening, which can not only improve the texture characteristics and sensory quality, but also reduce water loss, inhibit starch aging, and enhance the toughness of the gluten network, thereby delaying the decline of sensory quality.

[0100] 2.4 Effect of packaging method on the microstructure (SEM) of pre-prepared noodles after refrigeration and reheating

[0101] like Figure 5It can be observed that as the refrigeration time increases, the gluten network of each experimental group gradually becomes loose and the number of holes increases, which indicates that refrigeration will destroy the gluten network structure and reduce the cross-linking of starch and protein. The network structure of CK-VP and OP-VP was more obviously damaged because the noodles were squeezed and deformed by the air pressure. In contrast, the microstructures of CK-MP and OP-MP were more complete, indicating that MP can retain the quality of prefabricated noodles to a greater extent. During refrigeration, the structure of OP-MP is denser than that of CK-MP, and the system structure changes less with the extension of storage time, which shows that after the addition of the compound colloid, the gluten protein is better bonded and the network structure is denser.

[28] , making the system more resistant to the adverse effects of refrigeration.

[0102] Effect of packaging methods on cooking characteristics of pre-prepared noodles after refrigeration and reheating

[0103] Cooking properties, including water absorption, cooking loss, and noodle breakage, play an important role in determining noodle quality and overall acceptability. Water absorption represents the degree of noodle expansion after cooking. Figure 6 A. As the cold storage time increased, the gluten network structure was destroyed during the cold storage period, the starch aged and partially lost during re-cooking, and the water absorption rate of each experimental group decreased significantly (P<0.05); CK-VP and OP-VP decreased by 6.3% and 4.4%, respectively, because the network structure was damaged and the water absorption capacity decreased, while CK-HS, OP-HS, CK-MP and OP-MP had no significant effect on the water absorption rate (P>0.05). The water absorption rates of the CK-MP and OP-MP groups on the 0th day were 119.0% and 124.1%, respectively, indicating that the addition of the compound colloid made the pre-made noodles absorb more water during the cooking process and had higher water holding capacity; the water absorption rate of the CK-MP group on the 7th day was 3.6% lower than that on the 0th day, and the OP-MP group only decreased by 2.5%, indicating that the compound colloid improved the water holding capacity of the system.

[0104] The cooking loss rate represents the amount of residual substances in the water after cooking. Gluten protein has hydration, and the proteins will aggregate into clumps. Starch will be interspersed in them or wrapped by the gluten network. Therefore, if the network structure is damaged, starch and other substances will be further lost, exacerbating the cooking loss. Figure 6 In B, the cooking loss of each experimental group increased significantly with the extension of refrigeration time (P<0.05). Among them, due to the serious damage to the structure of VP packaging, the cooking loss rate of CK-VP on the 7th day was 5.6%, which was higher than that of other groups; there was no significant difference in the cooking loss of CK-HS, OP-HS, CK-MP and OP-MP (P>0.05). On the 7th day, the cooking loss rate of OP-MP was 1.4% lower than that of CK-MP, indicating that the compound colloid caused less loss of starch and other substances.

[0105] The breaking rate refers to the degree of noodle breaking after steaming and is closely related to the gluten network structure.

[32] .exist Figure 6 In C, the breaking rate increased significantly with the extension of storage time (P<0.05); the breaking rate of CK-VP and OP-VP on the 7th day was as high as 77.8% and 88.9%, which was significantly higher than that of other groups (P<0.05); the breaking rate of CK-MP was 35.5%, while that of OP-MP was only 20%, indicating that the compound colloid improved the gluten network structure. In summary, the OP-MP group had better cooking characteristics than other experimental groups.

[0106] Effect of packaging methods on tensile properties of pre-made noodles after refrigeration and reheating

[0107] The stretching distance can reflect the elongation and plasticity of noodles, and the maximum tensile force can reflect the strength and gluten of noodles. According to Table 5, the tensile properties of each experimental group decreased with the extension of refrigeration time. Since the network structure of CK-VP and OP-VP was severely damaged, the tensile properties were also negatively affected. On the 7th day, the stretching distance of CK-VP and OP-VP was only 10.7 mm and 33.1 mm, and the maximum tensile force was only 45.3 g and 64.3 g. The stretching distance and maximum tensile force of OP-MP on the 7th day of refrigeration were 45.9 mm and 106.4 g, respectively, which were 46.2% and 48.2% higher than those of CK-MP, respectively. This is because the prefabricated noodles form irreversible gels during the pre-cooking process. The addition of compound colloids can form a more resistant structure with the system, further counteracting the adverse effects of refrigeration on the system.

[0108] Table 5 Changes of tensile properties of pre-made noodles after reheating with storage time under different packaging methods

[0109]

[0110]

[0111] Note: Different lowercase letters indicate significant differences in the same experimental group at different storage times (P<0.05); Different uppercase letters indicate significant differences in different experimental groups at the same storage time (P<0.05).

[0112] Effect of packaging methods on the texture characteristics of pre-prepared noodles after refrigeration and reheating

[0113] Texture properties are crucial to the quality of prefabricated noodles. Hardness and chewiness are texture parameters closely related to sensory perception. Hardness mainly depends on the strength of the gluten network. Elasticity refers to the ability of noodles to return to their original shape after being compressed. Chewiness is affected by hardness to a certain extent. As shown in Table 6, with the extension of refrigeration time, the hardness, elasticity and chewiness of each experimental group decreased significantly (P<0.05). This is because the gluten network structure was further destroyed during the reheating process, and a large amount of starch, soluble protein and other substances were lost. On the 7th day, the hardness, elasticity and chewiness of CK-VP and OP-VP were significantly lower than those of other groups (P<0.05). The hardness, elasticity and chewiness of CK-VP decreased by 52.6%, 17.4% and 61.6% respectively compared with the 0th day, and the hardness, elasticity and chewiness of OP-VP decreased by 44.0%, 8.1% and 41.0% respectively compared with the 0th day, indicating that the destruction of the gluten network will directly affect the texture characteristics of prefabricated noodles. The hardness, elasticity and chewiness of OP-MP on the 7th day were 1888g, 0.83 and 1241g, respectively, which were 20.3%, 1.2% and 10.2% higher than those of CK-MP on the 7th day, indicating that the compound colloid interacted with starch and gluten protein to form a structurally stable complex, which helped to maintain better reheating quality and prevented starch aging to a certain extent, thereby improving elasticity.

[0114] Table 6 Changes of texture characteristics of pre-made noodles after reheating with storage time under different packaging methods

[0115]

[0116]

[0117] Effect of packaging methods on total bacterial count of pre-made noodles after refrigeration

[0118] The total number of colonies is used to determine the degree of microbial contamination and sanitary quality, and is also the standard for judging the shelf life of noodles. The shelf life of pre-made noodles is generally 3 days. Bacteria and mold are the main microorganisms that cause spoilage. During the refrigerated storage period, the total number of viable bacteria in each group increases with the storage time; Figure 7 , the total viable count of CK-HS and OP-HS exceeded 104 on the 5th day; CK-VP and OP-VP had obvious antibacterial effects (P<0.05), but VP packaging would seriously damage the structure of the system and its quality would be greatly reduced; the microorganisms inside CK-MP and OP-MP were effectively inhibited, because the addition of CO2 can inhibit the growth of mold. Therefore, MP is the most suitable packaging method for refrigerated pre-made noodles.

[0119] In summary, the present invention adds different amounts of sunflower pectin and 0.03wt% of Artemisia sphaerocephala gum to a composite colloid, and combines gas conditioning and vacuum packaging for 7 days of refrigeration to explore the effects of composite colloids and packaging methods on the quality of prefabricated noodles after refrigeration. The optimal process parameters were determined by response surface experiment: 40wt% water addition, 0.35wt% sunflower pectin addition, and 15 minutes of dough mixing time. The prefabricated noodles after process optimization were refrigerated in vacuum and gas conditioning packaging, respectively. It was found that vacuum packaging seriously damaged the gluten network of the prefabricated noodles, making the sensory quality after reheating lower than that of other groups, and the cooking loss rate and broken rate were significantly increased (P<0.05), and the tensile and texture characteristics were significantly decreased (P<0.05). The network structure of the prefabricated noodles under gas conditioning packaging is more complete, the sensory quality is higher, the cooking loss rate and broken rate are significantly decreased (P<0.05), the tensile and texture characteristics are higher than other groups, and it has a good antibacterial effect, so it can be used as the best packaging method for refrigeration of prefabricated noodles. In addition, the prefabricated noodles with the addition of the compound colloid showed a denser gluten network structure, improved water holding capacity, inhibited starch aging to a certain extent, significantly improved the sensory quality after refrigeration and reheating (P<0.05), significantly increased water absorption (P<0.05), significantly reduced cooking loss rate and broken rate (P<0.05), and improved tensile and texture properties. The present invention provides some references for exploring the packaging method of prefabricated noodles and the influence mechanism of compound hydrophilic colloids on prefabricated noodles.

Claims

1. A method for improving the reheating quality of refrigerated prefabricated noodles by using a compound colloid combined with modified atmosphere packaging, characterized in that: The steps include: Artemisia gum, sunflower pectin and sodium chloride are added to water in sequence according to a proportion, mixed evenly, and an additive solution is obtained; the additive solution is then mixed with flour, the dough is kneaded and left to rise, pressed into sheets to form noodles, cooked, packaged in an atmosphere-controlled manner, and then refrigerated.

2. The method according to claim 1, characterized in that: The wormwood glue is prepared from wormwood seeds, and the specific method is as follows: The wormwood seeds are mixed with water according to a ratio, and after heating, they are subjected to ultrasound, high-speed stirring and centrifugation in sequence to obtain an intermediate layer of emulsion colloid, and the wormwood seeds in the colloid are removed, freeze-dried and crushed to obtain the wormwood glue.

3. The method according to claim 2, characterized in that: The heating temperature is 55-65° C., and the heating time is 1.5-2.5 h.

4. The method according to claim 1, characterized in that: The mass ratio of the artemisia gum to flour is 0.03:

100.

5. The method according to claim 1, characterized in that: The mass ratio of the sunflower pectin to the flour is 0.3-0.9:

100.

6. The method according to claim 5, characterized in that: The mass ratio of sunflower pectin to flour is 0.3-0.6:

100.

7. The method according to claim 1, characterized in that: The mass ratio of the sodium chloride to the flour is 1:

100.

8. The method according to claim 1, characterized in that: The mass ratio of water to flour is 35-45:

100.

9. The method according to claim 1, characterized in that: The time for kneading the dough is 5-20 minutes.

10. The method according to claim 1, characterized in that: The gas in the modified atmosphere packaging consists of 60% CO2 and 40% N2.

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