A method to improve the water-holding capacity of pre-cooked dishes

Abstract

This invention discloses a method for improving the water-holding capacity of pre-prepared dishes, comprising: 1) pre-prepared dish raw material processing: washing, cutting, and classifying the raw materials for later use; 2) pre-preparation of the pre-prepared dishes: processing the processed raw materials into pre-prepared dishes; 3) adding L-threonine-Tremella fuciformis polysaccharide complex: mixing the L-threonine-Tremella fuciformis polysaccharide complex with the prepared pre-prepared dishes evenly; 4) quick-freezing: placing the pre-prepared dishes in a DENBA+ freezer and quick-freezing them under an electric field environment; 5) packaging: packaging the quick-frozen products promptly. This invention improves the water-holding capacity and nutritional value of pre-prepared dishes by constructing an L-threonine and Tremella fuciformis polysaccharide complex system under the action of an electric field; furthermore, by combining a freshness-preserving electric field device with the L-threonine-Tremella fuciformis polysaccharide complex, it improves ice crystal formation during freezing, enhances the quality of frozen pre-prepared dishes after thawing, and extends the shelf life of the products.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, specifically to a method for improving the water-holding capacity of pre-prepared dishes. Background Technology

[0002] Pre-prepared meals refer to non-ready-to-eat pre-packaged dishes made from livestock and poultry meat and products, aquatic products and products, fruits and vegetables and products, etc., which undergo preliminary processing, marinating or seasoning, cooking, and packaging followed by sterilization or non-sterilization, or are not cooked and sterilized after packaging. These dishes require reheating before consumption. With economic development and the increasing penetration of modern lifestyles among young people, pre-prepared meals have captured consumers' attention due to their no-cutting, no-washing, and no-preparation characteristics. They significantly save cooking time while maintaining a high standard of food quality, provided that the raw materials meet health and safety requirements. This effectively caters to the current trend of consumption upgrading and the emphasis on food quality, indicating a vast potential for industry development.

[0003] However, the taste of pre-cooked meals, which are popular with most people, is not as good as freshly cooked dishes. This is because most pre-cooked meals are frozen, and the ice crystals formed during freezing can change the original taste and texture of the food to some extent. In addition, pre-cooked meat products, in particular, often lose juices after thawing and reheating, causing the meat to become tough and greatly reducing its palatability. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems existing in the prior art and provide a method for improving the water retention of pre-prepared dishes.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A method for improving the water-holding capacity of pre-cooked dishes, characterized by comprising:

[0007] 1) Preparation of raw materials for pre-cooked dishes: Wash, cut, and classify the raw materials for later use;

[0008] 2) Preparation of pre-cooked dishes: Processing the raw materials into pre-cooked dishes;

[0009] 3) Add L-threonine-Tremella polysaccharide complex: Mix the L-threonine-Tremella polysaccharide complex with the prepared pre-cooked vegetables evenly;

[0010] 4) Quick-freezing: Place the prepared food in the DENBA+ freezer and quick-freeze it in an electric field environment;

[0011] 5) Packaging: Pack the frozen products promptly.

[0012] Preferably, the stirring time in step 2) is 3-5 minutes.

[0013] Preferably, in step 4), the core temperature of the product is maintained below -18°C during the quick-freezing process.

[0014] Furthermore, the L-threonine-tremella polysaccharide complex was prepared by a wet-heat method, the specific steps of which are as follows:

[0015] L-threonine and Tremella polysaccharide were mixed in distilled water at a predetermined ratio, the pH was adjusted to 11, and the mixture was heated in a water bath at 90-95℃ for 30-90 minutes. Then, the reaction temperature was lowered by an ice bath. After the reaction was completed, excess water in the solution was removed by freeze drying to obtain powdered L-threonine-Tremella polysaccharide complex.

[0016] Preferably, the mass ratio of L-threonine to Tremella polysaccharide is 1:1 to 3.

[0017] Furthermore, the extraction method for the polysaccharide from Tremella fuciformis includes the following specific steps:

[0018] a) Crush the dried white fungus and sieve it. Mix it with distilled water at a material-to-liquid ratio of 1:15-25 (g / mL) and extract it with hot water at 70-90℃ for 6-10 hours. After centrifugation, collect the supernatant separately.

[0019] b) After removing the protein from the supernatant using the Sevage method, add 3-6 times the volume of 95% ethanol, precipitate at 4°C for 24-48 hours, then centrifuge to separate the precipitates, collect them separately, and freeze-dry to obtain Tremella polysaccharide.

[0020] Preferably, in step a), the dried white fungus is pulverized and then passed through a 70-mesh sieve.

[0021] Preferably, in step a), the centrifugation speed is 4500 r / min and the centrifugation time is 10-15 min.

[0022] Preferably, in step b), the centrifugation speed is 4500 r / min and the centrifugation time is 15-20 min.

[0023] Threonine is an essential amino acid that the human body cannot synthesize and must obtain through diet and other external means. Tremella polysaccharide is a major component of Tremella fuciformis, and its most notable characteristic is its significant water-retention and moisturizing ability. Furthermore, L-threonine is one of the few polar amino acids containing a hydroxyl group and carrying no charge. The hydroxyl groups in L-threonine can form hydrogen bonds with water molecules in an orderly manner under an electric field, exhibiting excellent water-holding capacity. Both L-threonine and Tremella polysaccharide can form hydrogen bonds with water molecules, and their strength is greater than that of general intermolecular forces. Frozen pre-cooked dishes undergo washing, sterilization, transportation, thawing, and heating during processing, resulting in excessive nutrient loss. Therefore, controlling the reaction between L-threonine and Tremella polysaccharide to construct a complex system can improve the water-holding capacity, enhance the flavor, and increase the nutritional value of pre-cooked dishes, achieving a synergistic effect greater than the sum of its parts.

[0024] Furthermore, under the influence of an electric field, water molecules crystallize into rounded, spherical shapes, maintaining the integrity of cell tissues during the freezing of pre-prepared dishes and mitigating juice loss upon thawing. This invention combines a freshness-preserving electric field device with an L-threonine-Tremella fuciformis polysaccharide complex. Since the hydroxyl groups of both L-threonine and the Tremella fuciformis polysaccharide complex can form orderly hydrogen bonds with water molecules in an electric field, the strength of which is greater than that of ordinary intermolecular forces. This allows for high-quality freezing of pre-prepared dishes, minimizing juice loss during thawing. Simultaneously, the low-temperature, low-moisture environment also slows down the growth and reproduction of microorganisms, further extending the product's shelf life.

[0025] The present invention has the following advantages:

[0026] This invention constructs an L-threonine and Tremella fuciformis polysaccharide complex system to improve the water retention during the processing of ready-made dishes, alleviate juice loss during thawing, and to some extent increase the nutritional value of the products. Traditional quick-freezing processes produce large ice crystals. However, by combining a freshness-preserving electric field device (DENBA+ freezer) with the L-threonine-Tremella fuciformis polysaccharide complex, water molecules crystallize into rounded, spherical shapes under the influence of the electric field. This maintains the integrity of cell tissues during freezing, minimizes juice loss during thawing, and extends the shelf life of ready-made dishes. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 The thawing juice loss rate of the samples in Example 1 and Comparative Examples 1-3 under thawing conditions at 25°C;

[0029] Figure 2 The cooking loss rate is for the samples of Example 1 and Comparative Examples 1-3. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] This invention provides a method for improving the water-holding capacity of pre-prepared dishes, comprising the following steps:

[0032] 1) Extraction of Tremella polysaccharide: The dried Tremella was pulverized and sieved (70 mesh). It was mixed with distilled water at a material-to-liquid ratio of 1:15-25 (g / mL) and extracted with hot water at 70-90℃ for 6-10 hours. After centrifugation (4500r / min, 10-15min), the supernatant was collected. The protein in the supernatant was removed by the Sevage method. Then, 3-6 times the volume of 95% ethanol was added and precipitated at 4℃ for 24-48 hours. After centrifugation (4500r / min, 15-20min), the precipitates were collected and freeze-dried to obtain Tremella polysaccharide.

[0033] 2) Preparation of L-threonine and Tremella polysaccharide complex: The L-threonine and Tremella polysaccharide complex was prepared by a wet heat method. Specifically, L-threonine and Tremella polysaccharide were mixed in distilled water at a predetermined ratio of 1:1 to 3, the pH was adjusted to 11, and the mixture was heated in a water bath at 90-95℃ for 30-90 minutes. Then, the reaction temperature was lowered by an ice bath. After the reaction was completed, excess water in the solution was removed by freeze drying equipment to obtain powdered L-threonine-Tremella polysaccharide complex.

[0034] 3) Preparation of raw materials for pre-cooked dishes: Select agricultural raw materials that meet hygiene standards, and then clean, cut and classify them for use.

[0035] 4) Preparation of pre-cooked dishes: Prepare according to the production process of different pre-cooked dishes.

[0036] 5) Add L-threonine-Tremella polysaccharide complex: Mix the L-threonine-Tremella polysaccharide complex prepared in step 2 with the prepared pre-cooked vegetables evenly (3-5 min).

[0037] 6) Quick-freezing: Place the prepared dishes in the DENBA+ freezer and quick-freeze them in an electric field environment. The core temperature of the product should be maintained below -18℃.

[0038] 7) Packaging, X-ray detection, and boxing: After quick-freezing, the products are packaged in a timely manner to reduce the time of contact with air, and then inspected by a metal detector before being boxed and stored.

[0039] Example 1

[0040] Step 1: Extraction of Tremella polysaccharide: The dried Tremella was pulverized and sieved (70 mesh). It was mixed with distilled water at a material-to-liquid ratio of 1:20 (g / mL) and extracted with hot water at 90℃ for 8 hours. After centrifugation (4500 r / min, 10 min), the supernatant was collected. The protein in the supernatant was removed by the Sevage method. Then, 3 times the volume of 95% ethanol was added and precipitated at 4℃ for 24 hours. After centrifugation (4500 r / min, 20 min), the precipitates were collected and freeze-dried to obtain Tremella polysaccharide.

[0041] Step 2: Preparation of the L-threonine and Tremella fuciformis polysaccharide complex: The L-threonine and Tremella fuciformis polysaccharide complex was prepared by a wet-heat method. L-threonine and Tremella fuciformis polysaccharide were mixed in distilled water at a ratio of 1:2, the pH was adjusted to 11, and the mixture was heated in a water bath at 95°C for 50 min. Then, the reaction temperature was lowered by an ice bath. After the reaction was completed, excess water in the solution was removed using a freeze-drying device to obtain a powdered L-threonine-Tremella fuciformis polysaccharide complex.

[0042] Step 3: Short Rib Processing: Select beef short ribs that meet hygiene standards, wash them, and cut them to a thickness of about 2cm for each short rib.

[0043] Step 4: Marinating the short ribs (i.e., preparing the pre-cooked dish): Take 1kg of short ribs, add 10g cornstarch, 5g meat tenderizer, 2g salt, 10g sugar, 5g MSG, 50g black pepper sauce, 20g light soy sauce, 5g dark soy sauce, 20g ginger juice, 2g sesame oil, and 10g garlic juice. Mix well and marinate for half an hour, then cover with plastic wrap.

[0044] Step 5: Add L-threonine-Tremella polysaccharide complex: Mix 20g of L-threonine-Tremella polysaccharide complex with the marinated beef short ribs (i.e., the prepared pre-cooked dish) from Step 4.

[0045] Step 6: Quick-freezing: Place the prepared food in the DENBA+ freezer and quick-freeze it in an electric field environment. The core temperature of the product should be maintained below -18°C.

[0046] Step 7: Packaging, X-ray detection, and boxing: After quick-freezing, the products are packaged in a timely manner to reduce the time they are exposed to air, and then inspected by a metal detector before being boxed and stored in the warehouse.

[0047] Comparative Example 1

[0048] Step 1: Beef short rib preparation: Select beef short ribs that meet hygiene standards, wash them and cut them to a thickness of about 2cm for each piece.

[0049] Step 2: Marinating the short ribs (i.e., preparing the pre-cooked dish): Take 1kg of short ribs, add 10g cornstarch, 5g meat tenderizer, 2g salt, 10g sugar, 5g MSG, 50g black pepper sauce, 20g light soy sauce, 5g dark soy sauce, 20g ginger juice, 2g sesame oil, and 10g garlic juice. Mix well and marinate for half an hour, then cover with plastic wrap.

[0050] Step 3: Quick-freezing: Place the prepared food in a freezer for quick-freezing, and maintain the core temperature of the product below -18℃.

[0051] Step 4: Packaging, X-ray detection, and boxing: After quick-freezing, the products are packaged in a timely manner to reduce the time they are exposed to air, and then inspected by a metal detector before being boxed and stored in the warehouse.

[0052] Comparative Example 2

[0053] Step 1: Beef short rib preparation: Select beef short ribs that meet hygiene standards, wash them and cut them to a thickness of about 2cm for each piece.

[0054] Step 2: Marinating the short ribs (i.e., preparing the pre-cooked dish): Take 1kg of short ribs, add 10g cornstarch, 5g meat tenderizer, 2g salt, 10g sugar, 5g MSG, 50g black pepper sauce, 20g light soy sauce, 5g dark soy sauce, 20g ginger juice, 2g sesame oil, and 10g garlic juice. Mix well and marinate for half an hour, then cover with plastic wrap.

[0055] Step 3: Quick-freezing: Place the prepared food in the DENBA+ freezer and quick-freeze it in an electric field environment. The core temperature of the product should be maintained below -18℃.

[0056] Step 4: Packaging, X-ray detection, and boxing: After quick-freezing, the products are packaged in a timely manner to reduce the time they are exposed to air, and then inspected by a metal detector before being boxed and stored in the warehouse.

[0057] Comparative Example 3

[0058] Step 1: Extraction of Tremella polysaccharide: The dried Tremella was pulverized and sieved (70 mesh). It was mixed with distilled water at a material-to-liquid ratio of 1:20 (g / mL) and extracted with hot water at 90℃ for 8 hours. After centrifugation (4500 r / min, 10 min), the supernatant was collected. The protein in the supernatant was removed by the Sevage method. Then, 3 times the volume of 95% ethanol was added and precipitated at 4℃ for 24 hours. After centrifugation (4500 r / min, 20 min), the precipitates were collected and freeze-dried to obtain Tremella polysaccharide.

[0059] Step 2: Preparation of the L-threonine and Tremella fuciformis polysaccharide complex: The L-threonine and Tremella fuciformis polysaccharide complex was prepared by a wet-heat method. L-threonine and Tremella fuciformis polysaccharide were mixed in distilled water at a ratio of 1:2, the pH was adjusted to 11, and the mixture was heated in a water bath at 95°C for 50 min. Then, the reaction temperature was lowered by an ice bath. After the reaction was completed, excess water in the solution was removed using a freeze-drying device to obtain a powdered L-threonine-Tremella fuciformis polysaccharide complex.

[0060] Step 3: Short Rib Processing: Select beef short ribs that meet hygiene standards, wash them, and cut them to a thickness of about 2cm for each short rib.

[0061] Step 4: Marinating the short ribs (i.e., preparing the pre-cooked dish): Take 1kg of short ribs, add 10g cornstarch, 5g meat tenderizer, 2g salt, 10g sugar, 5g MSG, 50g black pepper sauce, 20g light soy sauce, 5g dark soy sauce, 20g ginger juice, 2g sesame oil, and 10g garlic juice. Mix well and marinate for half an hour, then cover with plastic wrap.

[0062] Step 5: Add L-threonine-Tremella polysaccharide complex: Mix 20g of L-threonine-Tremella polysaccharide complex with the marinated beef short ribs (i.e., the prepared pre-cooked dish) from Step 4.

[0063] Step 6: Quick-freezing: Place the prepared food in a freezer for quick-freezing, and maintain the core temperature of the product below -18℃.

[0064] Step 7: Packaging, X-ray detection, and boxing: After quick-freezing, the products are packaged in a timely manner to reduce the time they are exposed to air, and then inspected by a metal detector before being boxed and stored in the warehouse.

[0065] Product Testing

[0066] The water-holding properties of the products obtained in Example 1 and Comparative Examples 1-3 were evaluated. The water-holding properties of the products were evaluated by two indicators: thawing juice loss rate and cooking loss rate.

[0067] 1. Thawing juice loss rate: Take 50g of the sample to be tested, weigh it and record the mass m1. After thawing at 25℃ for 3 hours, wipe the juice off the sample surface with filter paper, weigh it again and record the mass m2. Each test is performed in triplicate. The specific calculation formula is as follows:

[0068]

[0069] 2. Cooking Loss Rate: After thawing 50g of the sample at 25℃ for 3 hours, wipe the surface of the sample dry with filter paper and weigh it, recording the mass as m3. Place the sample in a retort bag and heat it in an 80℃ water bath until the center temperature of the sample reaches 70℃. Remove the sample, cool it to room temperature, wipe the surface of the sample dry with filter paper, and weigh it, recording the mass as m4. Each experiment is performed in triplicate. The specific calculation formula is shown below:

[0070]

[0071] Generally speaking, the change in water-holding capacity of pre-cooked food products can be initially evaluated by the thawing juice loss rate.

[0072] like Figure 1 As shown, under thawing conditions at 25℃, the juice loss rate of Comparative Example 1 was the highest, showing a significant difference from other groups (P<0.05); the juice loss rates of Comparative Example 2 and Comparative Example 3 were similar, with no significant difference between them, indicating a certain improvement in the water-holding capacity of the samples; while the juice loss rate of Example 1 was significantly lower than that of Comparative Examples 1-3, mainly because the L-threonine-polysaccharide complex bound to the free water in the sample, and under the effect of the freshness-preserving electric field freezer, the morphology of cell ice crystals was improved. The two played a synergistic role, thereby improving the water-holding capacity of the prepared dishes.

[0073] Cooking loss rate is a commonly used indicator for evaluating the water-holding capacity of meat products. For example... Figure 1 As shown, the changes in cooking loss rate among different treatment groups were similar to the results of thawing juice loss rate. The cooking loss rates of Example 1, Comparative Example 2, and Comparative Example 3 were significantly lower than those of Comparative Example 1 (P<0.05), with Example 1 showing the lowest cooking loss rate. The addition of the L-threonine-Tremella fuciformis polysaccharide complex can compensate for the deficiency of decreased protein hydration capacity in pre-cooked dishes. In addition, the formation of ice crystals during freezing can damage the original muscle fiber structure, leading to a decrease in water retention after thawing and cooking. However, under the action of an electric field, the morphology of ice crystals is improved, maintaining the original integrity of cell structure and alleviating juice loss.

[0074] In addition, the total bacterial count of Examples 1 and Comparative Examples 1-3 after storage at -18°C for 21 days was determined according to the method described in the national standard GB 4789.1-2016. The results are shown in the table below:

[0075] Table 1: Total bacterial count (log cfu·g) for each group after 21 days of storage at -18℃ -1 )

[0076]

[0077] To investigate the effects of the L-threonine-Tremella fuciformis polysaccharide complex and the freshness-preserving electric field on the total bacterial count of prepared dishes, the final total bacterial count of Examples 1 and Comparative Examples 1-3 was measured after storage at -18℃ for 21 days. The results are shown in Table 1. After 21 days of storage, the bacterial counts of each group increased to varying degrees, but Examples 1, Comparative Examples 2 and 3 showed significant differences compared to Comparative Example 1. Among them, Comparative Example 1 showed the largest increase in bacterial count, at 0.92 log cfu·g. -1 This indicates that the treatment method in this group had the weakest antibacterial effect. Conversely, the treatment in Example 1 group had the best antibacterial effect on the prepared vegetables, with the least increase in the total bacterial count. This demonstrates that the combined effect of the L-threonine-tremella polysaccharide complex and the freshness-preserving electric field effectively inhibited putrefactive Gram-negative bacteria in the prepared vegetables, exhibiting good preservation and water-holding effects.

[0078] In summary, this invention provides a method for improving the water-holding capacity of pre-prepared dishes. By controlling the Maillard reaction between the amino group of L-threonine and the carbon group at the reducing end of the polysaccharide, a complex system of L-threonine and Tremella fuciformis polysaccharide is constructed, which effectively improves water-holding capacity. Simultaneously, the combination of "amino acid-polysaccharide" enhances the nutritional value of the product. Furthermore, the use of a freshness-preserving electric field device in conjunction with the L-threonine-Tremella fuciformis polysaccharide complex allows for high-quality freezing of the product. Because the hydroxyl groups of both components form hydrogen bonds with water molecules, the strength of these bonds is greater than that of typical intermolecular forces, thus reducing juice loss after thawing. It also reduces the suitable growth environment for bacteria, thereby slowing down microbial growth and reproduction, and helping to extend the product's shelf life.

[0079] The above embodiments further illustrate the purpose, technical solution, and advantages of the present invention. It should be understood that the above description is only a preferred embodiment of the present invention and is not intended to limit the invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0080] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for improving the water-holding capacity of pre-cooked dishes, characterized in that, include: 1) Preparation of raw materials for pre-cooked dishes: Wash, cut, and classify the raw materials for later use; 2) Preparation of pre-cooked dishes: Processing the raw materials into pre-cooked dishes; 3) Preparation and addition of L-threonine-Tremella polysaccharide complex: L-threonine and Tremella polysaccharide were mixed in distilled water at a mass ratio of 1:1 to 3. The pH of the mixture was adjusted to 11. The mixture was heated in a water bath at 90℃ to 95℃ for 30 to 90 minutes. The reaction solution was then cooled in an ice bath. After the reaction was completed, the water was removed by freeze drying to obtain powdered L-threonine-Tremella polysaccharide complex. The prepared L-threonine-Tremella polysaccharide complex was added to the pre-prepared dish obtained in step 2), stirred evenly, and stirred for 3 to 5 minutes. 4) Quick-freezing: Place the pre-prepared dishes processed in step 3) in the DENBA+ electric field freezer and quick-freeze them in an electrostatic field environment to control the core temperature of the product to be maintained below -18℃. 5) Packaging: Pack and seal the frozen products promptly.

2. The method for improving the water-holding capacity of pre-prepared dishes according to claim 1, characterized in that, The extraction method for the polysaccharide from Tremella fuciformis includes the following specific steps: a) Crush the dried white fungus and sieve it. Mix it with distilled water at a material-to-liquid ratio of 1:15-25 (g / mL) and extract it with hot water at 70-90℃ for 6-10 h. After centrifugation, collect the supernatant separately. b) After removing the protein from the supernatant using the Sevage method, add 3-6 times the volume of 95% ethanol, precipitate at 4°C for 24-48 hours, then centrifuge to separate the precipitates, freeze-dry them to obtain Tremella polysaccharide.

3. The method for improving the water-holding capacity of pre-prepared dishes according to claim 2, characterized in that, In step a), the dried white fungus is pulverized and passed through a 70-mesh sieve.

4. The method for improving the water-holding capacity of pre-prepared dishes according to claim 2, characterized in that, In step a), the centrifugation speed is 4500 r / min and the centrifugation time is 10-15 min.

5. A method for improving the water-holding capacity of pre-prepared dishes according to claim 2, characterized in that, In step b), the centrifugation speed is 4500 r / min and the centrifugation time is 15-20 min.

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