Normal-temperature preservation method of protein food

Abstract

The invention provides a normal-temperature preservation method of protein food, which comprises the following steps: uniformly spraying a preservative on the surface of the protein food in a spraying or mist spraying manner, and drying by sterile wind, or dipping the protein food into the preservative in a dipping manner, carrying out acoustic heat treatment, taking out the protein food, and blow-drying the protein food with sterile wind; and cooling the dried protein food, loading the cooled protein food into a vacuum packaging bag, and sterilizing the vacuum packaging bag. The protein food is treated in a spraying or mist spraying and dipping combined acoustic heat treatment mode, and a composite fresh-keeping method combining vacuum packaging and sterilization is combined, so that the process of fat oxidation and protein oxidation denaturation can be effectively slowed down, the growth rate of the total number of bacteria is reduced, the normal-temperature fresh-keeping time of the protein food is effectively prolonged, and the normal-temperature fresh-keeping effect of the protein food is improved. The food quality is improved.

Description

Technical Field

[0001] The invention relates to the field of food storage, and in particular to a method for preserving protein food at room temperature. Background Art

[0002] Protein is one of the main nutrients. Under normal temperature conditions, protein is prone to oxidation reactions, causing cross-linking of protein molecules, which in turn changes the color, organizational structure, appearance and other qualities of edible products, reducing the edible quality and value of edible products. Usually, heat treatment can kill harmful bacteria such as pathogens and spoilage bacteria. Under the action of heat treatment, it also plays a role in inactivating enzymes, which is beneficial to improve the retention and digestion of nutrients in edible products. However, treatment at too high a temperature can easily change the edible quality of the product, such as color, hardness and chewiness. Edible products that have been heat-treated usually need to be stored in a low-temperature environment, and cold chain transportation and preservation are carried out to avoid the accelerated oxidation rate of lipids, proteins and other substances, shortening the shelf life. Low-temperature preservation not only increases production costs, but the ice crystals formed at low temperatures can also easily destroy the microstructure of the product. Summary of the invention

[0003] In view of this, the purpose of the present invention is to provide a method for preserving protein food at room temperature to solve the above problems.

[0004] The technical solution of the present invention is achieved in this way:

[0005] A method for preserving protein food at room temperature, comprising the following steps:

[0006] S1: Spray or atomize the preservative evenly onto the surface of the protein food, and blow dry it with sterile air; or immerse the protein food into the preservative, perform sonication and heat treatment, take out the protein food, and blow dry it with sterile air;

[0007] The preservatives include tea polyphenols, sophorolipids, coumarin compounds and plant extracts;

[0008] S2: Cool the dried protein food, put it into a vacuum packaging bag, and sterilize it.

[0009] In a further embodiment, the coumarin compound is 6,7-dihydroxycoumarin and / or daphnetin; and the plant extract is licorice extract and / or yellow peel extract.

[0010] A further solution is that the Wampee extract is a Wampee peel extract, and the preparation method of the Wampee peel extract is: taking Wampee peel, drying, adding ethanol solution, ultrasonic immersion extraction, condensing and refluxing, vacuum concentrating, filtering, and obtaining the Wampee peel extract.

[0011] A further solution is that, by weight, the preservative includes 4-8 parts of tea polyphenols, 7-13 parts of sophorolipids, 6-9 parts of coumarin compounds and 22-32 parts of plant extracts.

[0012] A further solution is that, in the spraying or atomizing method, the amount of the preservative sprayed is 0.2-0.4% of the weight of the protein food, and the concentration of the preservative is 12-18 g / L; in the immersion method, the concentration of the preservative is 5-9 g / L; the wind speed of the sterile air drying is 20-30 m / s, and the temperature is 30-32°C.

[0013] A further solution is that the ultrasonic time of the sonication treatment is 2-10 min, the ultrasonic temperature is 20-40° C., and the ultrasonic power is 2-4 W / mL.

[0014] A further solution is that the sonication heat treatment is performed by ultrasonication at 4 W / mL and 40° C. for 2 min, and then ultrasonication at 2 W / mL and 20° C. for 10 min; the sonication heat treatment is stopped for 30 s every 2 min.

[0015] A further solution is that the preservative is sprayed uniformly onto the surface of the protein food, and microwave treatment is performed 1-3 times; the power of the microwave treatment is 200-300W, and the time is 20-30s. The present invention has experimentally found that the preservative is sprayed uniformly onto the surface of the protein food and low-power microwave treatment is performed, and the electromagnetic field generated by the microwave can be used to promote the penetration effect of the preservative, and the microwave thermal effect can also be used to assist in sterilization. Compared with no microwave treatment, the shelf life of crayfish food is increased by about 2 weeks, and the color changes slightly, but it does not affect consumption.

[0016] A further solution is that the sterilization can be carried out by conventional sterilization methods such as radiation sterilization, pasteurization, ultraviolet sterilization, ultrasonic sterilization, and resistance sterilization. The present invention preferably uses 60Coγ rays or electron beams for irradiation sterilization; the irradiation dose of the 60Coγ rays is 5-6kGy, and the irradiation temperature is 30-32°C; the electron beam energy is 5-10MeV, the irradiation dose is 5-6kGy, and the irradiation temperature is 30-32°C.

[0017] The vacuum packaging bag material can be made of polyethylene terephthalate plastic, aluminum foil or nylon. The composite preservation method of spraying or atomizing, dipping / sound heat treatment, combined with aseptic air drying, vacuum packaging and sterilization, is more helpful to extend the shelf life of crayfish food at room temperature.

[0018] When only the preservatives of immersion combined with sonication and heat treatment were used for treatment, the total colony count of crayfish food was nearly 6lg (cfu / g) in 5 weeks; the single-factor experiment showed that the effects of licorice extract, kumquat peel extract, coumarin compounds, and sophorolipids on TVB-N value and carbonyl content were better than those of tea polyphenols.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention prepares a preservative with tea polyphenols, sophorolipids, coumarin compounds (6,7-dihydroxycoumarin and / or daphnetin) and plant extracts (licorice extract and / or yellow peel extract), treats protein food by spraying or atomizing, immersing and sonication-thermal treatment, and uniformly regulates the amount, concentration and sonication-thermal treatment parameters of the preservative. The composite preservation method combined with vacuum packaging and sterilization can effectively slow down the process of fat oxidation and protein oxidation denaturation, and reduce the growth rate of the total number of bacteria, so as to effectively extend the room temperature fresh-keeping time of protein food and improve food quality.

[0021] In addition, the preservative immersion method is better than the spraying method, and the storage time can be extended to more than 22 weeks. The cavitation effect caused by ultrasound in the sonic thermal treatment helps to increase the contact interface between molecules, promote the close combination of the preservative components and the crayfish food, and improve the uniformity. At the same time, the heat generated also helps to improve the mobility of molecules. The sonic thermal treatment can also play an auxiliary sterilization role. The two-stage, intermittent sonic thermal treatment is used. On the one hand, it avoids protein structure denaturation, but accelerates the oxidation degree of protein. On the other hand, it is more conducive to promoting the formation of cavitation bubbles, thereby producing thermal effects, shock waves, shear force and other effects. DETAILED DESCRIPTION

[0022] In order to better understand the technical content of the present invention, specific embodiments are provided below to further illustrate the present invention.

[0023] Unless otherwise specified, the experimental methods used in the embodiments of the present invention are all conventional methods.

[0024] Unless otherwise specified, the materials, reagents, etc. used in the embodiments of the present invention can be obtained from commercial sources.

[0025] Sensory evaluation is based on the sensory evaluation standards (as shown in the table below), and scores are given in four aspects: color, odor, tissue state, and water holding capacity of stored lobsters. The full score for each item is 5 points. If the overall score is below 10 points, it means that the lobsters can no longer be stored at room temperature.

[0026]

[0027]

[0028] Determination of total volatile basis nitrogen (TVB-N): Determination shall be carried out in accordance with "Determination of Volatile Basic Nitrogen in Aquatic Products" (SC / T 3032-2007);

[0029] Determination of carbonyl content: Take 5g of lobster minced meat, add 25mL PBS buffer, homogenize 3 times, 10s each time, place in an ice bath for 10min after each homogenization, filter, centrifuge, discard the supernatant, rinse the precipitate with PBS buffer 2-3 times, add 20mL PBS buffer containing 0.6M NaCl, homogenize, extract at 4℃ for 24h, centrifuge, and take the precipitate to extract protein.

[0030] PBS buffer containing 0.6M NaCl was added to the extracted protein to adjust the protein concentration to 5mg / mL. 0.5mL of the extracted protein solution was taken, and 0.5mL of 2M HCl solution containing 0.01M 2,4-dinitrophenylhydrazine was added. The reaction was carried out at 25℃ for 1h. 0.5mL of 20% trichloroacetic acid solution was added, and the supernatant was discarded. The precipitate was washed with ethyl acetate for 2-3 times, and 1.5mL of 6M guanidine hydrochloride solution was added. The reaction was carried out in a water bath at 37℃ for 15min, and the blank group was PBS buffer containing 0.6M NaCl, and 0.5mL of 2M HCl solution was added. The subsequent steps were the same as before. The absorbance value was measured at 370nm. The carbonyl content was calculated as follows:

[0031] Carbonyl content (nmol / mg) = (A × n × 10 6 ) / (ε×ρ)

[0032] In the formula, A is the absorbance value, n is the dilution factor, ε is the molar absorption coefficient 22000, and ρ is the protein concentration (mg / mL). If the carbonyl content is greater than 4nmol / mg, it is considered that the protein has undergone severe cross-linking, causing significant deterioration of functional properties.

[0033] Determination of total colony count: The meat is considered to be stale and corrupted if the total colony count is ≥ 6lg (cfu / g).

[0034] The preparation method of the kumquat peel extract is as follows: take the kumquat peel, dry it, add 80% ethanol solution by mass concentration, extract it twice by 600W ultrasonic immersion, each time for 30 minutes, extract it by condensation reflux for 60 minutes, concentrate it in vacuum at 45°C and 0.03MPa until there is no ethanol taste, filter it, and obtain the kumquat peel extract.

[0035] The preparation method of crayfish food is as follows: select crayfish with good shell color, no limb defects, good spirits and uniform size, rinse them, boil them in boiling water for 8-10 minutes, remove the heads, and obtain crayfish food.

[0036] Example 1

[0037] A method for preserving protein food at room temperature, comprising the following steps:

[0038] S1: Use a spraying method to evenly spray a preservative with a concentration of 16g / L onto the surface of the crayfish food, with the spraying amount being 0.3% of the weight of the crayfish food. After the spraying is completed, adjust the wind speed to 25m / s and the temperature to 30-32°C for sterile air drying;

[0039] The preservative is 6 parts of tea polyphenols, 10 parts of sophorolipids, 8 parts of 6,7-dihydroxycoumarin and 27 parts of kumquat peel extract;

[0040] S2: Cool the dried crayfish food, put it into a vacuum packaging bag, and sterilize it by irradiation with 60Coγ rays. The irradiation dose is 5-6kGy and the irradiation temperature is 30-32°C.

[0041] A method for preserving protein food at room temperature, characterized in that it comprises the following steps:

[0042] S1: Spray or atomize the preservative evenly onto the surface of the protein food, and blow dry it with sterile air; or immerse the protein food into the preservative, perform sonication and heat treatment, take out the protein food, and blow dry it with sterile air;

[0043] The preservatives include tea polyphenols, sophorolipids, coumarin compounds and plant extracts;

[0044] S2: Cool the dried protein food, put it into a vacuum packaging bag, and sterilize it.

[0045] Example 2

[0046] A method for preserving protein food at room temperature, comprising the following steps:

[0047] S1: Using an immersion method, immerse the crayfish food in a preservative with a concentration of 5-9g / L, and perform sonication and thermal treatment. The ultrasonic time of the sonication and thermal treatment is 10min, the ultrasonic temperature is 30°C, and the ultrasonic power is 4W / mL. After the treatment, take out the crayfish food, adjust the wind speed to 25m / s, and the temperature to 30-32°C, and perform sterile air drying;

[0048] The preservative is 6 parts of tea polyphenols, 10 parts of sophorolipids, 8 parts of 6,7-dihydroxycoumarin and 27 parts of kumquat peel extract;

[0049] S2: Cool the dried crayfish food, put it into a vacuum packaging bag, and sterilize it by irradiation with 60Coγ rays. The irradiation dose is 5-6kGy and the irradiation temperature is 30-32°C.

[0050] Example 3

[0051] A method for preserving protein food at room temperature, comprising the following steps:

[0052] S1: The crayfish food is immersed in a preservative with a concentration of 5-9g / L by dipping, and a two-stage sonication heat treatment is performed. The two-stage sonication heat treatment is firstly performed at an ultrasonic power of 4W / mL and a temperature of 40°C for 2 minutes, then stopped for 30 seconds, and the ultrasonic power is adjusted to 2W / mL and the temperature is adjusted to 20°C for another 10 minutes of sonication. During the interval of 10 minutes of sonication, the crayfish food is stopped for 30 seconds after each 2 minutes of sonication. After the sonication heat treatment, the crayfish food is taken out, the wind speed is adjusted to 25m / s and the temperature is adjusted to 30-32°C, and sterile air drying is performed;

[0053] The preservative is 6 parts of tea polyphenols, 10 parts of sophorolipids, 8 parts of 6,7-dihydroxycoumarin and 27 parts of kumquat peel extract;

[0054] S2: Cool the dried crayfish food, put it into a vacuum packaging bag, and sterilize it by irradiation with 60Coγ rays. The irradiation dose is 5-6kGy and the irradiation temperature is 30-32°C.

[0055] The crayfish food treated with freshness preservation in Example 1-3 was stored at 24-26°C, and various indicators were tested during storage. The results are as follows:

[0056]

[0057] As can be seen from the above table, the crayfish food treated with preservation in Examples 1-3 can reach a total sensory evaluation score of more than 10 points after storage for 20 weeks, with good sensory scores, and the carbonyl content and total bacterial count are 3.21-3.61 nmol / mg and 4.47-5.48 lg (cfu / g), respectively, which meet the requirements. The method of preservative immersion is better than the spraying method, and the storage time can be extended to more than 22 weeks. The cavitation effect generated by ultrasound in the sonication heat treatment helps to increase the contact interface between molecules, promote the close combination of the preservative components and the crayfish food, and improve the uniformity. At the same time, the heat generated also helps to improve the mobility of the molecules. The sonication heat treatment can also play an auxiliary role in sterilization; the two-stage, intermittent sonication heat treatment is used. On the one hand, it avoids protein structural denaturation, but accelerates the oxidation degree of protein. On the other hand, it is more conducive to promoting the formation of cavitation bubbles, thereby generating thermal effects, shock waves, shear forces and other effects.

[0058] The present invention can be used for long-term storage of crayfish food at room temperature, and the storage time can reach 24 weeks. It can effectively avoid ice crystals formed during low-temperature freezing that reduce the quality of lobsters, is also beneficial to maintaining the flavor of crayfish itself, and greatly reduces the cost of cold chain transportation.

[0059] The present invention prepares a preservative with tea polyphenols, sophorolipids, coumarin compounds (6,7-dihydroxycoumarin and / or daphnetin) and plant extracts (licorice extract and / or yellow peel extract), treats protein food by spraying or atomizing, immersing and sonication-thermal treatment, and uniformly regulates the amount, concentration and sonication-thermal treatment parameters of the preservative. The composite preservation method combined with vacuum packaging and sterilization can effectively slow down the process of fat oxidation and protein oxidation denaturation, and reduce the growth rate of the total number of bacteria, so as to effectively extend the room temperature fresh-keeping time of protein food and improve food quality.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preserving protein food at room temperature, characterized in that: The steps include: S1: Spray or atomize the preservative evenly onto the surface of the protein food, and blow dry with sterile air; or immerse the protein food into the preservative, perform sonication and heat treatment, take out the protein food, and blow dry with sterile air; The preservatives include tea polyphenols, sophorolipids, coumarin compounds and plant extracts; S2: Cool the dried protein food, put it into a vacuum packaging bag, and sterilize it.

2. A method for preserving protein food at room temperature according to claim 1, characterized in that: The coumarin compound is 6,7-dihydroxycoumarin and / or daphnetin; the plant extract is licorice extract and / or yellow peel extract.

3. A method for preserving protein food at room temperature according to claim 2, characterized in that: The Wampee extract is a Wampee peel extract, and the preparation method of the Wampee peel extract is: taking Wampee peel, drying, adding ethanol solution, ultrasonic immersion extraction, condensing and refluxing, vacuum concentrating, filtering, and obtaining the Wampee peel extract.

4. A method for preserving protein food at room temperature according to any one of claims 1 to 3, characterized in that: By weight, the preservative comprises 4-8 parts of tea polyphenols, 7-13 parts of sophorolipids, 6-9 parts of coumarin compounds and 22-32 parts of plant extracts.

5. A method for preserving protein food at room temperature according to claim 1, characterized in that: The spraying or atomizing method is adopted, the spraying amount of the preservative is 0.2-0.4% of the weight of the protein food, and the use concentration of the preservative is 12-18g / L; the immersion method is adopted, and the use concentration of the preservative is 5-9g / L; the wind speed of the sterile air drying is 20-30m / s, and the temperature is 30-32℃.

6. A method for preserving protein food at room temperature according to claim 1, characterized in that: The ultrasonic heat treatment has an ultrasonic time of 2-10 min, an ultrasonic temperature of 20-40° C., and an ultrasonic power of 2-4 W / mL.

7. A method for preserving protein food at room temperature according to claim 6, characterized in that: The sonication and thermal treatment is performed by ultrasonication at 4 W / mL and 40° C. for 2 min, and then ultrasonication at 2 W / mL and 20° C. for 10 min; the sonication and thermal treatment is stopped for 30 s every 2 min.

8. A method for preserving protein food at room temperature according to claim 1, characterized in that: The method comprises spraying the preservative uniformly onto the surface of the protein food and performing microwave treatment 1-3 times; the power of the microwave treatment is 200-300W and the time is 20-30s.

9. A method for preserving protein food at room temperature according to claim 1, characterized in that: The sterilization is performed by irradiation sterilization with 60Coγ rays or electron beams; the irradiation dose of the 60Coγ rays is 5-6kGy, and the irradiation temperature is 30-32°C; the electron beam energy is 5-10MeV, the irradiation dose is 5-6kGy, and the irradiation temperature is 30-32°C.

10. A preservative for a method for preserving protein food at room temperature, characterized in that: By weight, the preservative comprises 4-12 parts of tea polyphenols, 8-13 parts of sophorolipids, 6-9 parts of coumarin compounds and 22-32 parts of plant extracts; The coumarin compound is 6,7-dihydroxycoumarin and / or daphnetin; the plant extract is licorice extract and / or yellow peel extract; The Wampee extract is a Wampee peel extract, and the preparation method of the Wampee peel extract is: taking Wampee peel, drying, adding ethanol solution, ultrasonic immersion extraction, condensing and refluxing, vacuum concentrating, filtering, and obtaining the Wampee peel extract.

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