Cinnamaldehyde-enzyme preparation-based fresh-keeping agent and fresh-keeping method of fresh and wet rice noodles

Abstract

The invention discloses a cinnamyl aldehyde-enzyme preparation-based preservative and a preservation method of fresh and wet rice noodles. The preservative is prepared from cinnamyl aldehyde and an enzyme preparation, the enzyme preparation comprises glucose oxidase. The fresh-keeping method comprises the following steps: adding cinnamyl aldehyde and an enzyme preparation into rice milk to prepare fresh wet rice noodles, and then packaging, and carrying out low-temperature plasma sterilization treatment on the packaged fresh and wet rice noodles. The preservative disclosed by the invention can obviously prolong the shelf life of the fresh and wet rice noodles, and the fresh and wet rice noodles do not have obvious rancidity phenomenon in the storage period and have better sensory quality. The fresh-keeping method of the fresh and wet rice noodles can prolong the shelf life of the fresh and wet rice noodles without influencing the quality of the fresh and wet rice noodles, is beneficial to promoting the healthy development of the fresh and wet rice noodle processing industry in China, and has huge economic and social significance.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, specifically, to the technical field of food preservation. More specifically, the invention relates to a preservative based on cinnamaldehyde-enzyme preparation and a method for preserving fresh wet rice noodles. Background Art

[0002] Fresh wet rice noodles are made from rice and processed through a series of steps, including grinding, gelatinization, shaping, and cooling, without drying. They are popular with consumers for their ease of processing, excellent taste, and quality. However, due to their high moisture content and rich nutrients, fresh wet rice noodles are susceptible to microbial contamination and spoilage during storage. Therefore, preservatives are often added to prevent deterioration, improve storage quality, and extend their shelf life.

[0003] Sodium dehydroacetate, a preservative currently widely used in rice noodle preservation, has been banned by the new GB 2760-2024. Rice noodle manufacturers have begun to actively seek other food preservatives as alternatives. However, it is difficult to strike a balance between antibacterial effects and the quality of fresh wet rice noodles during storage.

[0004] In addition, to kill residual microorganisms in the finished fresh wet rice noodles and further extend the shelf life of the fresh wet rice noodles, post-sterilization treatment is required. Currently, the most widely used post-sterilization technology for fresh wet rice noodles is heat sterilization, but heat sterilization can easily damage the quality of heat-sensitive fresh wet rice noodles. Summary of the Invention

[0005] Based on this, the object of the present invention is to provide a preservative that can prolong the shelf life of fresh wet rice noodles without affecting the quality of the fresh wet rice noodles during storage, and a method for preserving fresh wet rice noodles.

[0006] The specific technical solutions for achieving the above-mentioned invention objectives include the following.

[0007] A first aspect of the present invention provides a preservative, which is composed of cinnamaldehyde and an enzyme preparation in a mass ratio of 7-9:20-50; the enzyme preparation includes glucose oxidase.

[0008] The second aspect of the present invention provides the use of the above-mentioned preservative in preserving fresh wet rice noodles.

[0009] A third aspect of the present invention provides a method for preserving fresh wet rice noodles using the above-mentioned preservative, comprising the following steps:

[0010] (1) adding cinnamaldehyde and enzyme preparation to rice milk to prepare fresh wet rice noodles, and then packaging; the cinnamaldehyde accounts for 0.07% to 0.09% of the mass of the rice milk, and the enzyme preparation accounts for 0.2% to 0.5% of the mass of the rice milk.

[0011] (2) The packaged fresh wet rice noodles are sterilized by low-temperature plasma.

[0012] In the present invention, the inventors found after a large number of experiments that when making fresh wet rice noodles, adding a certain mass ratio of cinnamaldehyde and an enzyme preparation with glucose oxidase as the main raw material to the rice slurry can more effectively inhibit the total colony count of the prepared fresh wet rice noodles than using cinnamaldehyde alone as a preservative, and extend the shelf life of the fresh wet rice noodles from 6 days to 37 days. In addition, the fresh wet rice noodles do not suffer from obvious rancidity during the storage period, and have better sensory quality.

[0013] In addition, the inventors found that after adding the cinnamaldehyde of a certain mass ratio and the composite preservative of the enzyme preparation with glucose oxidase as the main raw material to make fresh wet rice, they packaged it, and then the fresh wet rice was subjected to plasma cold treatment under a certain processing voltage and time. Under this combined fresh-keeping process, the shelf life of the fresh wet rice can be further extended to 43d. During the storage period, the rising of the acidity of the fresh wet rice was significantly delayed. The quality of the fresh wet rice was kept very well, and the total score of the sensory organoleptics remained at a high level, and the downward trend was delayed. Therefore, the preservation method of the fresh wet rice of the present invention can extend the shelf life of the fresh wet rice without affecting the quality of the fresh wet rice, and is conducive to promoting the healthy development of my country's fresh wet rice processing industry, with huge economic and social significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The figures show the changing trend of total bacterial count and shelf life of fresh wet rice noodles in each composite preservative treatment group during storage in Example 1 of the present invention.

[0015] Figure 2 The figures show the changes in moisture content and acidity of fresh wet rice noodles in the composite preservative treatment groups during storage in Example 1 of the present invention.

[0016] Figure 3 The results show the changes in sensory quality of fresh wet rice noodles in the composite preservative treatment groups during storage in Example 1 of the present invention.

[0017] Figure 4 The figures show the trend of total colony count and shelf life of the fresh wet rice noodles in the combined fresh-keeping treatment group during storage in Example 2 of the present invention.

[0018] Figure 5 The results of the changes in moisture content and acidity of the fresh wet rice noodles in the combined fresh-keeping treatment group during storage in Example 2 of the present invention are shown.

[0019] Figure 6 The results show the changes in sensory quality of the fresh wet rice noodles in the combined fresh-keeping treatment group during storage in Example 2 of the present invention.

[0020] Figure 7The figures show the changing trend of total colony count and shelf life of fresh wet rice noodles in each cinnamaldehyde-treated group during storage in Example 3 of the present invention.

[0021] Figure 8 The figures show the change in moisture content of fresh wet rice noodles in each cinnamaldehyde-treated group during storage in Example 3 of the present invention.

[0022] Figure 9 The figures show the acidity changes of the fresh wet rice noodles of each cinnamaldehyde-treated group during storage in Example 3 of the present invention.

[0023] Figure 10 These are the changes in sensory quality of the fresh wet rice noodles in each cinnamaldehyde treatment group during storage in Example 3 of the present invention. DETAILED DESCRIPTION

[0024] To facilitate understanding of the present invention, the present invention will be described more fully below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the present disclosure more thorough and comprehensive.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification are for the purpose of describing specific embodiments only and are not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0026] Unless otherwise specified, the examples were conducted under conventional experimental conditions or the conditions recommended by the manufacturer's instructions. All raw materials used were commercially available raw materials.

[0027] In one embodiment of the present invention, a preservative is disclosed, comprising cinnamaldehyde and an enzyme preparation in a mass ratio of 7-9:20-50; the enzyme preparation includes glucose oxidase. When preparing fresh wet rice noodles, if only cinnamaldehyde is added as a preservative, the shelf life of the fresh wet rice noodles can only reach 6 days, which is still not ideal. The inventors have discovered that a compound enzyme preparation with cinnamaldehyde and glucose oxidase as the main raw materials can extend the shelf life of fresh wet rice noodles to more than 30 days, and during storage, no obvious rancidity occurs, resulting in better sensory quality.

[0028] In one embodiment, the preservative consists of cinnamaldehyde and enzyme preparation in a mass ratio of 7.5-8.5:25-50.

[0029] In one embodiment, the preservative is composed of cinnamaldehyde and enzyme preparation in a mass ratio of 7.8-8.2:25-40.

[0030] In one embodiment, the enzyme preparation further comprises vinegar powder and acetylated distarch phosphate, wherein the mass ratio of glucose oxidase, vinegar powder, and acetylated distarch phosphate in the enzyme preparation is 1.5 to 4:0.8 to 3:1. Adding vinegar powder to glucose oxidase can assist the antibacterial effect of glucose oxidase and extend the shelf life, while adding acetylated distarch phosphate can maintain the quality of fresh wet rice noodles.

[0031] In one embodiment, the mass ratio of glucose oxidase, vinegar powder and acetylated distarch phosphate in the enzyme preparation is 2.2-2.6:1-1.4:1.

[0032] In one embodiment, the preservative comprises cinnamaldehyde and an enzyme preparation in a mass ratio of 7.8-8.2:28-32; the enzyme preparation comprises glucose oxidase, vinegar powder, and acetylated distarch phosphate in a mass ratio of 2.3-2.5:1.1-1.3:1. Using this preservative, the shelf life of fresh wet rice noodles can be extended to over 37 days.

[0033] In another embodiment of the present invention, the use of the above-mentioned preservative in preserving fresh wet rice noodles is disclosed.

[0034] In another embodiment of the present invention, a method for preserving fresh wet rice noodles is disclosed, using the above-mentioned preservative, comprising the following steps:

[0035] (1) adding cinnamaldehyde and an enzyme preparation to rice milk to prepare fresh wet rice noodles, and then packaging; the cinnamaldehyde accounts for 0.07% to 0.09% of the mass of the rice milk, and the enzyme preparation accounts for 0.2% to 0.5% of the mass of the rice milk;

[0036] (2) The packaged fresh wet rice noodles are sterilized by low-temperature plasma.

[0037] In one embodiment, the discharge voltage of the low-temperature plasma sterilization treatment is 100KV to 140KV, and the discharge time of the low-temperature plasma sterilization treatment is 12 minutes to 18 minutes.

[0038] In the present invention, the rice slurry is obtained by grinding with a certain material-water ratio (usually 1:2-4). Those skilled in the art can adjust the material-water ratio according to actual conditions, as long as fresh wet rice noodles can be produced. After adding a composite preservative to the rice slurry to produce fresh wet rice noodles, the packaged fresh wet rice noodles are sterilized with a low-temperature plasma at a discharge voltage of 100KV to 140KV for 12-18 minutes. This can further extend the shelf life of the fresh wet rice noodles, delay the increase in acidity during storage, maintain good quality of the rice noodles, and maintain a high level of sensory structure.

[0039] In one embodiment, the discharge voltage of the low-temperature plasma sterilization treatment in step (2) is 110KV to 130KV, and the discharge time of the low-temperature plasma sterilization treatment is 13min to 17min.

[0040] In one embodiment, the discharge voltage of the low-temperature plasma sterilization treatment in step (2) is 115KV to 125KV, and the discharge time of the low-temperature plasma sterilization treatment is 14min to 16min.

[0041] In one embodiment, the discharge voltage of the low-temperature plasma sterilization treatment in step (2) is 118KV to 122KV, and the discharge time of the low-temperature plasma sterilization treatment is 14min to 16min.

[0042] In the following examples of the present invention, the cinnamaldehyde, glucose oxidase, vinegar powder, and acetylated distarch phosphate used are all food grade with a purity of 99% and are commercially available.

[0043] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] Example 1 Effect of different proportions of composite preservatives on the preservation of fresh wet rice noodles

[0045] This example compares the effects of different ratios of cinnamaldehyde (CAS) and an enzyme preparation (composed of 2.4 g glucose oxidase (GOD), 1.2 g vinegar powder (HAc), and 1 g acetylated distarch phosphate (ADSP)) on the shelf life and storage quality of fresh wet rice noodles.

[0046] Rice slurry was prepared by grinding the rice slurry at a material-water ratio of 1:3. 0.08 wt% of cinnamaldehyde and enzyme preparations of varying concentrations (0.2%, 0.3%, 0.4%, and 0.5%) were then added to the rice slurry. The mixture was magnetically stirred for approximately 30 minutes until uniform and free of suspended matter. Fresh wet rice noodles were then prepared according to conventional methods. The changes in the total bacterial count and the quality of the fresh wet rice noodles during storage were tested, specifically:

[0047] 1. Changes in total colony count

[0048] The results are as follows Figure 1 As shown, from Figure 1As shown, with the 0.08% cinnamaldehyde treatment group as the control group, the total colony counts of all the composite preservative treatment groups remained within the standard, and the shelf life reached more than 30 days, significantly extending the shelf life compared to the control group (6 days) (P < 0.05). Specifically, compared to the shelf life of the 0.08% cinnamaldehyde + 0.2% enzyme preparation treatment group (32 days), the shelf life of the 0.08% cinnamaldehyde + 0.3% enzyme preparation treatment group was significantly extended, reaching 37 days. Further increasing the enzyme preparation dosage did not significantly extend the shelf life of fresh wet rice noodles. During storage, the 0.08% cinnamaldehyde + 0.2% enzyme preparation compound treatment group increased at a higher level of total colony count, while the total colony counts of the other groups did not differ significantly.

[0049] 2. Changes in moisture content and acidity

[0050] The results are as follows Figure 2 As shown in the figure, the initial moisture content of fresh wet rice noodles with the addition of the composite preservative is relatively high, and with the increase of the enzyme preparation content, the trend of a significant decrease in moisture content is delayed.

[0051] With the increase of enzyme content, acidity increased slowly. The lower acidity levels of all compound preservative treatment groups indicated that no obvious rancidity occurred during the 30-day storage process.

[0052] 3. Changes in sensory quality

[0053] The results are as follows Figure 3 With the addition of enzyme preparations, the color score of fresh wet rice noodles improved in the early stages, then decreased more rapidly in the later stages with higher addition levels. No significant differences were observed in the groups containing more than 0.3% enzyme preparation. Excessive addition of enzyme preparations resulted in a looser structure and a rougher surface for fresh wet rice noodles. During storage, the structure of the rice noodles deteriorated significantly after 12 days. In contrast, the structure of the rice noodles treated with a composite preservative of 0.08% cinnamaldehyde and 0.3% enzyme preparation remained optimal. The addition of enzyme preparations masked the rice aroma in the early stages of storage, leading to a decrease in the rice noodle flavor score. The more enzyme preparations were added, the less acceptable the pungent aroma became. In the later stages, insufficient additions led to microbial proliferation, resulting in flavor deterioration. Based on the total sensory score evaluation, fresh wet rice noodles prepared by adding 0.08% cinnamaldehyde and 0.3% enzyme preparation as a composite preservative to the rice slurry exhibited the best sensory quality.

[0054] Example 2 Effect of different combined preservation treatment methods on the preservation of fresh wet rice noodles

[0055] This example compares the effects of different combined preservation methods on the shelf life and storage quality of fresh wet rice noodles.

[0056] Combined preservation methods include:

[0057] ①0.08% CAS + microwave (800W / 60s) (labeled as "CAS+MS" group)

[0058] ②0.08% CAS + 0.3% enzyme preparation + microwave (800W / 60s) (labeled as "compound + MS" group)

[0059] ③0.08% CAS + low-temperature plasma (120 kV / 15 min) (labeled as "CAS+CPS" group)

[0060] ④0.08% CAS + 0.3% enzyme preparation + low-temperature plasma (120 kV / 15 min) (labeled as "compound + CPS" group)

[0061] Rice slurry was ground at a material-water ratio of 1:3 to obtain rice slurry. 0.08 wt% of cinnamaldehyde (labeled as the "CAS" group) and 0.08 wt% of cinnamaldehyde plus 0.3% of an enzyme preparation (labeled as the "compound" group) were then added to the rice slurry. The mixture was magnetically stirred (approximately 30 minutes) until uniform and free of suspended matter. Fresh wet rice noodles were then prepared according to conventional methods. After packaging, the noodles were then subjected to microwave or low-temperature plasma treatment. Changes in the total bacterial count and quality during storage were tested, specifically:

[0062] 1. Changes in total colony count and shelf life

[0063] Changes in total bacterial counts during storage and shelf life of each group of fresh wet rice noodles Figure 4 shown.

[0064] from Figure 4 It can be seen that the total colony count of fresh wet rice noodles in the CAS+MS, CAS+CPS, compound+MS, and compound+CPS groups began to increase rapidly at 15d, 10d, 20d, and 25d, respectively, and the shelf life could reach 23d, 14d, 33d, and 43d, respectively.

[0065] Compared with the CAS group (6 days), the shelf life of rice noodles in the CAS+MS and CAS+CPS groups was significantly extended (P < 0.05), and the shelf life of the CAS+MS group was significantly longer than that of the CAS+CPS group (P < 0.05), indicating that the addition of CAS followed by MS and CPS treatments has a synergistic effect on the preservation effect, the two sterilization treatments will not destroy the antibacterial effect of CAS, and the MS treatment has a better bactericidal effect than the CPS treatment.

[0066] Compared with the combined preservative group (37 days), the shelf life of rice noodles in the combined preservative + CPS group was significantly extended (P < 0.05), but the shelf life of the combined preservative + MS group was significantly shortened (P < 0.05). This indicates that after the addition of the combined preservative, CPS treatment enhanced the preservation effect, while MS treatment damaged the antibacterial effect of the combined preservative. The specific reason why MS treatment damaged the antibacterial effect of the combined preservative remains unknown. We speculate that the MS treatment may have destroyed the antibacterial function of the enzyme preparation, or that the high temperature of the MS treatment directly passivated the GOD in it, causing it to inactivate, or that the acetic acid in it volatilized at high temperature, increasing the pH and reducing the antibacterial activity of GOD.

[0067] 2. Changes in moisture content and acidity

[0068] The results are as follows Figure 5 As shown. Figure 5 It can be seen that MS treatment reduced the initial moisture content of rice noodles in the CAS and compound groups, and the CAS+MS group and the compound+MS group maintained a low level during storage; while the moisture content of fresh wet rice noodles in the CAS+CPS group and the compound+CPS group was relatively high, and the time when the moisture content began to decrease in the compound+MS group was delayed compared with the compound+CPS group, which indicates that compared with CPS, the compound+MS delayed the aging and water loss process of rice noodles.

[0069] The MS and CPS treatments reduced the initial acidity of the rice noodles in the CAS treatment group and increased it in the combined treatment group, but the differences were not significant. During storage, the acidity of the CAS+MS and CAS+CPS groups increased rapidly from day 0 to day 5. However, the acidity of the combined+MS group increased rapidly after a slight fluctuation from day 0 to day 25. The acidity increase in the combined+CPS group was delayed the longest during storage, and the rice noodles maintained the best quality.

[0070] 3. Changes in sensory quality

[0071] Changes in sensory quality of fresh wet rice noodles during storage after combined preservation treatment Figure 6 As shown in the figure, in the early storage period (before 20 days), the colors of CAS+MS, compound+MS, and compound+CPS remained good. After 20 days, the color of CAS+MS decreased, while the color of compound+MS and compound+CPS remained good.

[0072] Treatment with MS and CPS increased the texture score of the CAS group, while treatment with MS and CPS decreased it in the combined group. The combined group's texture score continued to decline, but was surpassed by the combined + CPS group between days 20 and 25. The combined + CPS group maintained a high level of sensory texture until day 35. Furthermore, rice aroma scores increased in fresh wet rice noodles from the CAS and combined groups after treatment with MS and CPS, with the increasing effect of MS being more pronounced.

[0073] Based on the total sensory score evaluation, the initial sensory scores of the CAS+CPS and compound+CPS groups were higher than those of the MS group. There was little difference in the total sensory scores among all treatment groups during storage for 0 to 5 days. Over time, the sensory scores of the CAS+MS group remained higher than those of the CAS+CPS group, and the compound+CPS group compared to the compound+MS group, and their downward trend slowed. The advantages of the combined CAS+MS and compound+CPS preservation methods gradually emerged. In comparison, the combined compound+CPS preservation method significantly delayed quality deterioration.

[0074] Example 3 Effect of Cinnamaldehyde as a Preservative on the Preservation of Fresh Wet Rice Noodles

[0075] In this example, we studied the effects of using only cinnamaldehyde as a preservative and different cinnamaldehyde concentrations on the preservation of fresh wet rice noodles.

[0076] Rice slurry was prepared by grinding at a material-water ratio of 1:3. Cinnamaldehyde (CAS) was then added to the slurry as a preservative at varying concentrations. The rice slurry was magnetically stirred for approximately 30 minutes until uniform and free of suspended matter. Fresh wet rice noodles were then prepared according to conventional methods. The total bacterial count and quality of the fresh wet rice noodles containing varying concentrations of CAS during storage were tested. The following information was analyzed:

[0077] 1. Changes in total colony count

[0078] The fresh wet rice noodles without preservatives were used as blank control. The changes of total bacterial counts in the fresh wet rice noodles treated with CAS at different addition levels during storage and shelf life were analyzed. Figure 7 shown.

[0079] from Figure 7 It can be seen that the total colony counts of the blank group and the 0.04% cinnamaldehyde treatment group increased rapidly from 0d to 2d, and exceeded the microbial limit (≥10 5 ). The shelf life of the 0.04% cinnamaldehyde treatment group was not significantly different from that of the blank control (less than 1 day). The 0.06% cinnamaldehyde treatment group had deteriorated by the 6th day, with a shelf life of only 4 days. However, the shelf life of the 0.08% and 0.1% cinnamaldehyde treatments reached 6 days, and the trends in total bacterial counts were similar. Therefore, 0.08% cinnamaldehyde can achieve better preservation effects at a lower dosage.

[0080] 2. Changes in moisture content

[0081] The results are as follows Figure 8 As shown by Figure 8As can be seen, the moisture content of fresh wet rice noodles decreased with increasing cinnamaldehyde content at day 0, likely due to cinnamaldehyde being slightly soluble in water and leaching out moisture from the rice noodles. After two days of deterioration, the structure of the fresh wet rice noodles in the blank and 0.04% cinnamaldehyde-treated groups was disrupted by the massive growth of microorganisms, resulting in the noodles becoming watery and decomposing, with an increase in moisture. The moisture content of the 0.08% and 0.1% cinnamaldehyde-treated groups showed a trend of first increasing, then decreasing, and then increasing again. The subsequent dehydration timelines of the fresh wet rice noodles in the 0.08% and 0.1% cinnamaldehyde-treated groups suggest that cinnamaldehyde has a certain anti-aging effect.

[0082] 3. Changes in acidity

[0083] The results are as follows Figure 9 As shown by Figure 9 It can be seen that the acidity of fresh wet rice noodles continued to increase during storage, with the blank group increasing most rapidly, exceeding the acidity standard of DBS 44 / 012-2019 (≤2.0) on the second day. Due to the weak acidity of cinnamaldehyde itself, the initial acidity of the fresh wet rice noodles in the cinnamaldehyde-treated group was slightly higher than that in the blank group, but cinnamaldehyde treatment could significantly slow down the rate of increase in acidity and delay the rancidity process of rice noodles. The acidity of the fresh wet rice noodles in all cinnamaldehyde-treated groups increased significantly after the microorganisms exceeded the limit standard. The acidity change trends of the fresh wet rice noodles in the 0.08% cinnamaldehyde-treated group and the 0.1% cinnamaldehyde-treated group during storage were similar, and the acidity increased slowly from 0d to 6d, indicating that the two concentrations of cinnamaldehyde had a good inhibitory effect on microbial acid production and spoilage.

[0084] Based on the above results, low doses of cinnamaldehyde (less than 0.06%) cannot achieve a significant effect in maintaining quality, while additions of 0.08% and 0.1% cinnamaldehyde can effectively delay the quality deterioration of fresh wet rice noodles.

[0085] 4. Changes in sensory quality

[0086] The results are as follows Figure 10 As shown, from Figure 10 It can be seen that the addition of cinnamaldehyde to fresh wet rice noodles reduces their sensory acceptability. The 0.1% cinnamaldehyde treatment significantly impacted all sensory qualities of fresh wet rice noodles, resulting in a yellower color, larger surface pores and poor smoothness, a slightly pungent odor that masked the rice aroma, and a significant decrease in the total sensory score. Compared with the 0.1% cinnamaldehyde treatment, the 0.08% cinnamaldehyde treatment maintained better sensory quality and showed a slower decline. Therefore, the addition of 0.08% cinnamaldehyde provides the best balance between sensory quality and preservation. However, using only 0.08% cinnamaldehyde as a preservative only extends the shelf life of fresh wet rice noodles to 6 days, far from meeting actual market demand.

[0087] Example 4 Effect of Microwave Sterilization Treatment on the Preservation of Fresh Wet Rice Noodles

[0088] In the present embodiment, we studied the effect of post-sterilization (microwave sterilization) on the preservation of fresh wet rice noodles without adding a preservative.

[0089] Rice slurry was obtained by grinding at a material-water ratio of 1:3, and fresh wet rice noodles were made according to conventional methods. After conventional packaging, the fresh wet rice noodles were subjected to microwave sterilization (MS) treatment with different parameters. The total bacterial count and quality of the fresh wet rice noodles during storage were tested, including:

[0090] 1. Changes in total colony count

[0091] The changes in the total colony count of fresh wet rice noodles during storage after microwave sterilization under different conditions are shown in Table 1.

[0092] Table 1

[0093]

[0094] Note: “+++” means the total colony count has exceeded the standard limit

[0095] As shown in Table 1, the sterilization effect of microwave heat treatment under different treatment powers and times was different. Compared with the control group without sterilization treatment (no preservative), the total number of colonies remaining in the fresh wet rice noodles after sterilization decreased with the increase of microwave sterilization power and the extension of microwave sterilization time. Among them, the preservation effect of the 700W / 50s group was poor, and the total number of colonies on the first day exceeded the standard limit (10 5 The shelf life of fresh wet rice noodles in the 900W / 60s and 900W / 70s treatment groups was extended to 2 to 3 days, while that of the other groups was only 1 to 2 days.

[0096] We found that if the power and time of microwave treatment were further increased, the ziplock bags would burst, so 900W and 70s were selected as the maximum intensity of microwave treatment.

[0097] 2. Changes in moisture content and acidity

[0098] Table 2 shows the changes in moisture content and acidity of fresh wet rice noodles during storage after microwave sterilization under different conditions.

[0099] Table 2

[0100]

[0101] As shown in Table 2, the moisture content of fresh wet rice noodles after microwave sterilization remained within the range of 66.30% to 71.45%, with little change overall. Compared with the control group, the moisture content of the 700W / 50s and 700W / 60s groups decreased slightly, but the difference was not significant. The moisture content of the 900W / 60s and 900W / 70s groups decreased significantly (P < 0.05). With increasing storage time, the overall moisture content of the rice noodles decreased, with the 900W / 60s and 900W / 70s groups showing the most significant decrease after one day. After one day of storage, most of the fresh wet rice noodles had not deteriorated. The 800W / 60s group still maintained a high moisture content (72.89%), and the remaining 800W microwave-treated groups also maintained high water retention.

[0102] On day 0, the acidity of all treatment groups was within the range of 0.48 to 0.52, showing little difference compared to the unsterilized control group. During storage, the acidity of the microwave-treated group remained relatively low. With increasing microwave power and duration, the rate of acidity growth in fresh wet rice noodles gradually slowed during storage, indicating that high-power, long-term microwave treatment can significantly delay the rancidity of fresh wet rice noodles.

[0103] 3. Changes in sensory quality

[0104] Table 3 shows the changes in sensory quality of fresh wet rice noodles during storage after microwave sterilization under different conditions.

[0105] Table 3

[0106]

[0107]

[0108] The results in Table 3 show that appropriate microwave treatment improves the sensory color of fresh wet rice noodles, with 800W microwave conditions showing the most significant improvement. However, excessive microwave power reduced the color score of the rice noodles, resulting in a yellowish appearance. The rice aroma score of the fresh wet rice noodles decreased after microwave treatment, and this score decreased with increasing microwave power and storage time. During storage, appropriate microwave treatment killed some spoilage bacteria in the fresh wet rice noodles, delaying sensory quality deterioration during storage. The initial total sensory score of the rice noodles in the 800W / 60s treatment group was very similar to that of the control group and significantly higher than that of the other treatment groups (P < 0.05). During storage, the color, texture, and total sensory scores of the noodles remained high.

[0109] Based on the above results, 800W / 60s is a relatively moderate microwave condition, with a shelf life of 1-2 days. The treated rice noodles have higher moisture content and overall sensory scores, and their quality remains good during storage without spoilage. However, if no preservatives are added during the production of fresh wet rice noodles, and only post-sterilization is performed, even under the optimal microwave conditions, the shelf life is very short, which cannot meet the needs of actual production and sales.

[0110] Example 5 Effect of Low-Temperature Plasma Sterilization Treatment on the Preservation of Fresh Wet Rice Noodles

[0111] In the present embodiment, we studied the effect of post-sterilization (low-temperature plasma sterilization) on the preservation of fresh wet rice noodles without adding a preservative.

[0112] Rice slurry was obtained by grinding at a material-water ratio of 1:3, and then made into fresh wet rice noodles according to conventional methods. After conventional packaging, the fresh wet rice noodles were sterilized with a low-temperature plasma (CPS) treatment using different parameters. The total bacterial count and quality of the fresh wet rice noodles during storage were tested, including:

[0113] 1. Changes in total colony count

[0114] The changes in the total colony count of fresh wet rice noodles during storage after treatment with different low-temperature plasma sterilization conditions are shown in Table 4.

[0115] Table 4

[0116]

[0117] Note: “+++” means the total colony count has exceeded the standard limit

[0118] As shown in Table 4, on day 1, the total number of colonies in the control group and the 90 kV / 10 min, 90 kV / 15 min, 90 kV / 20 min, and 120 kV / 10 min treatment groups exceeded the standard limit (10 5 ), and all treatment groups deteriorated after 2 days. The shelf life of fresh wet rice noodles could only reach 1 day to 2 days, and the sterilization effect was inferior to that of microwave thermal sterilization.

[0119] 2. Changes in moisture content and acidity

[0120] Table 5 shows the changes in moisture content and acidity of fresh wet rice noodles during storage after treatment with different low-temperature plasma sterilization conditions.

[0121] Table 5

[0122]

[0123]

[0124] Note: For the same storage time and the same column, different letters indicate significant differences (P < 0.05), and the same letters indicate no significant differences (P > 0.05).

[0125] The results in Table 5 show that the moisture content of fresh wet rice noodles after low-temperature plasma sterilization remained within the range of 66.83% to 71.46%, with little change overall, similar to the effect of microwave treatment on the moisture content of fresh wet rice noodles. Compared with the control group, the moisture content of the higher treatment voltage group (150 kV) increased, while the moisture content of the lower voltage treatment group decreased.

[0126] At 0d, the acidity of all treatment groups was within the range of 0.43-0.52. Compared with the control group, plasma treatment slightly increased the acidity of fresh wet rice noodles, indicating that the active group reaction of plasma on microorganisms may have H + Similarly, similar to the microwave sterilization group, the plasma-treated group showed lower acidity during storage. As the CPS treatment voltage and duration increased, the increase in acidity in fresh wet rice noodles gradually decreased during storage, indicating that high-voltage, long-term plasma treatment can significantly delay the rancidity process in fresh wet rice noodles.

[0127] 3. Changes in sensory quality

[0128] Table 6 shows the changes in sensory quality of fresh wet rice noodles during storage after treatment with different low-temperature plasma sterilization conditions.

[0129] Table 6

[0130]

[0131]

[0132] It can be seen from Table 6 that low-temperature plasma treated with appropriate voltage and time can improve the appearance structure status score of fresh wet rice noodles, plasma with insufficient voltage has insufficient sterilization effect, and plasma discharge with too high voltage will destroy the integrity of the rice noodles structure.

[0133] Overall, plasma treatment reduced the overall sensory score of fresh wet rice noodles, but treatment under appropriate parameters not only achieved a certain sterilization effect but also maintained the sensory quality of the rice noodles. During storage, CPS treatment at a certain intensity slowed the rate of decline in rice noodles' color, texture, rice aroma, and overall sensory score. Among all treatment groups, the 120kV / 15min group had better initial color and texture, and its overall sensory score was significantly higher than that of the other treatment groups (P < 0.05). During storage, its color, texture, and overall sensory scores remained high, with sensory quality only experiencing significant deterioration on the second day. However, if no preservatives are added during the production of fresh wet rice noodles, and only post-sterilization is performed, even under optimal low-temperature plasma treatment conditions, the shelf life is extremely short, completely failing to meet the needs of actual production and sales.

[0134] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0135] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A preservative, characterized in that: The invention consists of cinnamaldehyde and enzyme preparation in a mass ratio of 7-9:20-50; the enzyme preparation comprises glucose oxidase.

2. The preservative according to claim 1, characterized in that The preservative consists of cinnamaldehyde and enzyme preparation in a mass ratio of 7.5-8.5:25-50.

3. The preservative according to claim 2, characterized in that The preservative consists of cinnamaldehyde and enzyme preparation in a mass ratio of 7.8-8.2:25-40.

4. The preservative according to any one of claims 1 to 3, characterized in that The enzyme preparation further comprises vinegar powder and acetylated distarch phosphate, and the mass ratio of glucose oxidase, vinegar powder and acetylated distarch phosphate in the enzyme preparation is 1.5-4:0.8-3:

1.

5. The preservative according to claim 4, characterized in that The mass ratio of glucose oxidase, vinegar powder and acetylated distarch phosphate in the enzyme preparation is 2.2-2.6:1-1.4:

1.

6. The preservative according to claim 1, characterized in that The invention is composed of cinnamaldehyde and enzyme preparation in a mass ratio of 7.8-8.2:28-32; the enzyme preparation is composed of glucose oxidase, vinegar powder and acetylated distarch phosphate in a mass ratio of 2.3-2.5:1.1-1.3:

1.

7. Use of the preservative according to any one of claims 1 to 6 in preserving fresh wet rice noodles.

8. A method for preserving fresh wet rice noodles, characterized in that: Using the preservative according to any one of claims 1 to 6 comprises the following steps: (1) adding cinnamaldehyde and an enzyme preparation to rice milk to prepare fresh wet rice noodles, and then packaging; the cinnamaldehyde accounts for 0.07% to 0.09% of the mass of the rice milk, and the enzyme preparation accounts for 0.2% to 0.5% of the mass of the rice milk; (2) The packaged fresh wet rice noodles are sterilized by low-temperature plasma.

9. The method for preserving fresh wet rice noodles according to claim 8, wherein In step (2), the discharge voltage of the low-temperature plasma sterilization treatment is 100KV to 140KV, and the discharge time of the low-temperature plasma sterilization treatment is 12min to 18min.

10. The method for preserving fresh wet rice noodles according to claim 9, wherein The discharge voltage of the low-temperature plasma sterilization treatment is 110KV to 130KV, more preferably 115KV to 125KV, and the discharge time of the low-temperature plasma sterilization treatment is 13min to 17min, more preferably 14min to 16min.

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