CN116970281B - Preparation method and application of silver carp myofibrillar protein-amino acid Janus membrane - Google Patents

Preparation method and application of silver carp myofibrillar protein-amino acid Janus membrane Download PDF

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CN116970281B
CN116970281B CN202310845927.4A CN202310845927A CN116970281B CN 116970281 B CN116970281 B CN 116970281B CN 202310845927 A CN202310845927 A CN 202310845927A CN 116970281 B CN116970281 B CN 116970281B
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amino acid
solution
film
concentration
janus
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CN116970281A (en
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朱俊向
张晨雪
吴昊
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Qingdao Navy Food And Nutrition Innovation Research Institute Qingdao Special Food Research Institute
Qingdao Agricultural University
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Qingdao Navy Food And Nutrition Innovation Research Institute Qingdao Special Food Research Institute
Qingdao Agricultural University
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D65/00—Wrappers or flexible covers; Packaging materials of special type or form
    • B65D65/38—Packaging materials of special type or form
    • B65D65/46—Applications of disintegrable, dissolvable or edible materials
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2389/00—Characterised by the use of proteins; Derivatives thereof
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2471/00—Characterised by the use of polyethers obtained by reactions forming an ether link in the main chain; Derivatives of such polymers
    • C08J2471/02—Polyalkylene oxides
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2489/00—Characterised by the use of proteins; Derivatives thereof
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/34—Silicon-containing compounds
    • C08K3/36—Silica
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/04—Oxygen-containing compounds
    • C08K5/05—Alcohols; Metal alcoholates
    • C08K5/053—Polyhydroxylic alcohols
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/16—Nitrogen-containing compounds
    • C08K5/17—Amines; Quaternary ammonium compounds

Abstract

The invention discloses a preparation method of a silver carp myofibrillar protein-amino acid Janus membrane, which comprises the following steps: (one) preparing MP solution; (II) preparing a basic MP-amino acid solution; third), preparing a silver carp myofibrillar protein-amino acid Janus membrane. According to the invention, the silver carp myofibrillar protein-amino acid Janus film with high tensile strength, high water resistance and good fresh-keeping effect is prepared by adding amino acid and using alkaline conditions and taking MP and Zein as main raw materials, so that the silver carp myofibrillar protein-amino acid Janus film can be applied to the field of fresh food packaging of fruits and vegetables and the like for fresh keeping.

Description

Preparation method and application of silver carp myofibrillar protein-amino acid Janus membrane
Technical Field
The invention relates to a packaging preservative film, in particular to a preparation method and application of a silver carp myofibrillar protein-amino acid Janus film.
Background
Silver carp (Hypophthalmichthys molitrix), also called silver carp, silver carp and the like, is one of four main fishes with maximum yield and cultivation area in freshwater fish in China, and is juxtaposed with grass carp (Ctenopharyngodon idella), bighead carp (Hypophthalmichthys nobilis) and black carp (Mylopharyngodon piceus). The abundant freshwater fish silver carp is utilized to replace the seawater fish to produce surimi products, so that the production cost of enterprises can be effectively reduced. At present, the silver carp processed products mainly comprise minced fillet and minced fillet products, but a large amount of byproducts such as fish skin, fish bones, minced meat and the like are generated in the processing process. The fish skin can be used for gelatin production, and the fish bone can be used as a production raw material of calcium tablets, but the minced meat has no good utilization mode.
The existing packaging materials are usually petroleum-based plastic products, and the packaging materials of the petroleum-based plastic products are difficult to decompose and cannot be recycled in natural environments, so that huge pressure is caused to the environment. The minced silver carp meat contains a large amount of MP, and the MP film is prepared by using the minced silver carp meat, so that the comprehensive utilization of silver carp resources is facilitated, and the harm of white pollution is reduced.
However, the mechanical property and the water resistance of the MP film prepared by the MP film are not similar to those of the traditional petroleum-based plastic products, which limits the application of the MP film in the packaging field of fresh foods such as fruits and vegetables.
Disclosure of Invention
The invention provides a preparation method of a silver carp myofibril protein-amino acid Janus film, which aims to solve the problems that the MP film in the prior art is poor in mechanical property and water resistance and limited in application, and the prepared silver carp myofibril protein-amino acid Janus film has high stretchability and high water resistance.
The invention also provides application of the silver carp myofibrillar protein-amino acid Janus film in fresh food preservation.
In order to achieve the above purpose, the present invention adopts the following technical scheme: the invention relates to a preparation method of a silver carp myofibrillar protein-amino acid Janus membrane, which comprises the following steps:
(one) preparation of MP solution
Mixing silver carp meat with a first buffer solution, grinding, centrifuging to remove supernatant, mixing precipitate with a second buffer solution, homogenizing, centrifuging to remove supernatant; suspending the precipitate in a second buffer solution, filtering with gauze, centrifuging, discarding supernatant, and washing the precipitate with distilled water to obtain MP solution.
(II) preparation of basic MP-amino acid solution
Mixing the amino acid solution with the MP solution, and adjusting the pH to 10-12 to obtain the alkaline MP-amino acid solution. The applicant found that both amino acid and alkaline conditions can increase the solubility of MP, reduce aggregation, thereby making the MP film smooth in surface, compact in internal structure, and thereby improving the mechanical properties of the MP film; after amino acid is added, the solubility of MP is obviously improved, and the particle size is also reduced after amino acid is added; under alkaline conditions, the secondary structure of the protein can be changed, so that more hydrophobic groups are exposed, the hydrophobicity is increased, the solubility of MP is increased, the particle size of MP is reduced, the solubility of MP is increased along with the increase of pH, the pH is 10-12, and the solubilization of amino acid to MP is obvious.
(III) preparation of silver carp myofibrillar protein-amino acid Janus membrane
Heating Zein film-forming liquid in water bath, performing ultrasonic treatment, adjusting pH to 8, pouring into a mold, drying to form film, pouring alkaline MP-amino acid solution into the mold, and drying to form film to obtain MP-amino acid Janus film. Janus membranes are an emerging membrane material concept that has morphological structure or chemical composition asymmetry that gives them certain unique properties over other membrane materials; zein (Zein) is a plant protein and a film-forming material, can be extracted from corn, has good moisture and gas resistance, can effectively prevent the Zein from absorbing water, can be degraded under natural conditions, has no pollution to the environment, and is a green and safe material; according to the invention, a double-layer Janus membrane is constructed by compositing the chub MP-amino acid membrane and the Zein membrane, so that the problems of poor water resistance, poor mechanical property and poor brittleness of the Zein membrane are solved.
Preferably, in the step (one), the first buffer is a NaCl solution containing EDTA and Tris-HCl buffer of pH7.5, wherein the concentration of EDTA in the first buffer is 5mM, the concentration of Tris-HCl is 5mM, and the concentration of NaCl is 25mM; the minced fish meat is 100g, and the volume of the first buffer solution is 100mL.
Preferably, in the step (one), the precipitate is mixed with 500mL of the second buffer; suspending the pellet in 350mL of a second buffer; the second buffer solution is a NaCl solution containing EDTA and Tris-HCl buffer solution with pH of 7.5, wherein the concentration of EDTA in the second buffer solution is 5mM, the concentration of Tris-HCl is 5mM, and the concentration of NaCl is 0.1M.
Preferably, in step (one), all steps are performed at a temperature of 4 ℃ or less.
Preferably, in the step (II), the concentration of the amino acid in the amino acid solution is 5mM, and the amino acid is L-Lys, L-Arg or L-His; 50mL of the amino acid solution was mixed with 50mL of MP solution having a concentration of 50mg/mL, and the pH was adjusted to 10 to 12 using NaOH having a concentration of 5M. In the invention, the concentration of the amino acid in the amino acid solution is 5mM, so that a better fresh-keeping effect can be obtained, and theoretically, the higher the concentration of the amino acid is, the better the fresh-keeping effect is.
Preferably, in the step (III), the Zein film forming liquid comprises the following components in percentage by mass: 4-8% of Zein,2% of glycerol, 3% of PEG-600,1.5% of nano SiO 2 50% ethanol, the balance water. Pure Zein films are inherently brittle and less plastic, and therefore require the addition of one or more substances to improve their performance; in ethanol aqueous solution, the Zein can form an irregular and complex coil structure, the property of the Zein is that the Zein is easy to form a film, and a film is formed after solvent evaporation, so that the Zein has the characteristics of antioxidation, bacteriostasis and the like; glycerol plasticizes; nano SiO 2 Can improve the mechanical property and water resistance of Zein film, and can improve the antibacterial effect, and meanwhile, the nano SiO 2 The bonding strength between the Zein membrane and the MP-amino acid membrane can be improved; PEG-600 as a dispersant allows the components, in particular nano SiO 2 Uniformly disperse to avoid nano SiO 2 Causing pores on the surface of the Zein film; in the Zein film-forming liquid, the opacity is affected by the too high concentration of Zein, so the Zein content in the Zein film-forming liquid is controlled to be 4-8%.
Preferably, in the step (III), the water bath temperature is 80 ℃, and the water bath heating time is 1h; the pH was adjusted to 8 using NaOH at a concentration of 5M; pouring 50ml of Zein film forming solution into a round plastic culture dish with the diameter of 9cm, and drying for 10 hours at 40 ℃; then, 20mL of a basic MP-amino acid solution was poured thereinto and dried at 40℃for 10 hours.
Application of a silver carp myofibrillar protein-amino acid Janus film in fresh food preservation is provided.
Therefore, the invention has the following beneficial effects: by adding amino acid and utilizing alkaline conditions, MP and Zein are used as main raw materials to prepare the silver carp myofibrillar protein-amino acid Janus film with high tensile strength, high water resistance and good fresh-keeping effect, and the silver carp myofibrillar protein-amino acid Janus film can be applied to the field of fresh food packaging of fruits and vegetables and the like for fresh keeping.
Drawings
FIG. 1 shows MP solubility measurements at different pH conditions.
FIG. 2 shows the results of WVP measurement.
Fig. 3 shows the browning index change result.
Fig. 4 is a graph showing the change in weight loss rate of apples.
Fig. 5 shows the results of the hardness change for each group of apples.
FIG. 6 is an SEM image of an MP-amino acid Janus film obtained in example 1.
FIG. 7 is an SEM image of MP-amino acid Janus film obtained in example 2.
FIG. 8 is an SEM image of MP-amino acid Janus film obtained in example 3.
FIG. 9 is an SEM image of an MP-amino acid Janus film obtained in example 7.
FIG. 10 is an SEM image of an MP-amino acid Janus film obtained in example 8.
FIG. 11 is an SEM image of an MP-amino acid Janus film obtained in example 9.
Detailed Description
The invention is further described below with reference to the drawings and detailed description.
In the following method, the first buffer solution is NaCl solution containing EDTA and Tris-HCl buffer solution with pH of 7.5, wherein the concentration of EDTA in the first buffer solution is 5mM, the concentration of Tris-HCl is 5mM, and the concentration of NaCl is 25mM; the second buffer is a NaCl solution containing EDTA and Tris-HCl buffer at pH7.5, wherein the concentration of EDTA in the second buffer is 5mM, the concentration of Tris-HCl is 5mM, and the concentration of NaCl is 0.1M.
1. Amino acid selection
(1) MP solubility assay
L-Lys, L-Arg, L-His and L-Pro were dissolved in a second buffer to prepare 5mM amino acid solutions, and 50mL MP solutions (50 mg/mL) were prepared at a ratio of 1:10 Mixing the (v/v) ratio with the amino acid solution to obtain MP-amino acid solution, and adjusting the pH of the MP-amino acid solution to 10, 11 and 12 by using 5M NaOH solution to form alkaline MP-amino acid solutions with different pH values; 50mL of MP solution (50 mg/mL) was mixed at 1:10 (v/v) ratio was mixed with the second buffer and the MP solution was adjusted to pH 10, 11 and 12 with 5M NaOH solution to form alkaline MP solutions of different pH.
Alkaline MP-amino acid solutions with different pH values and alkaline MP solutions with different pH values are respectively kept stand for 12 hours and centrifuged for 20 minutes at 1000 Xg, and the solubility is determined according to the following formula: solubility= (C 2 -C 1 )/C 2 X 100%, wherein: c1 is the MP concentration of the supernatant after centrifugation; c (C) 2 MP concentration before centrifugation; MP concentration was determined by the biuret method: drawing a standard curve by taking BSA as a standard protein; accurately measuring 0, 0.2, 0.4, 0.6, 0.8 and 1.0mL of BSA solution with the concentration of 10mg/mL in different test tubes, adding distilled water to adjust the volume to 1mL, adding 4mL of biuret reagent, standing at 25 ℃ for 30min, measuring the absorbance at 540nm, and calculating the concentration of MP in the sample through a standard curve.
The MP solubility results at different pH conditions are shown in FIG. 1.
As can be seen from fig. 1, at three pH, the dissolution of MP in the basic MP solution was minimal, whereas the dissolution of MP in the basic MP-amino acid solution was significantly increased, indicating that the amino acid had a solubilization effect on MP, whereas the solubilization effect was insignificant with increasing pH; in addition, the solubilization effect of the amino acid L-Pro on MP was found to be inferior to that of the other three amino acids.
(2) Measurement of Water vapor Transmission (WVP)
The film is prepared by the following method: basic MP-amino acid solutions of different pH in "1.MP solubility assay" were taken 40mL of a mixture with 0.1g of glycerol and stirred at room temperature for 1h, and finally the samples were poured into a polyethylene mold (diameter 9 cm) and dried at 40 ℃.
Water vapor permeability (WVP, g cm s) - 1Pa -1 m -2 ) Is determined according to ASTM standard method E96-95. The film was first cut to an area of 32.95cm 2 And the thickness thereof is measured. Then, the sample was covered on the surface of a container containing 2/3 distilled water, and the mixture was put into a WVP analyzer (Lab thin C360M, shandong Ji) at 90% humiditySouth, china).
The results of WVP measurement are shown in FIG. 2. The WVP of the film reflects the ability of the packaged food to exchange moisture between the atmosphere. As can be seen from fig. 2, the protein film at ph=12 has the lowest water vapor transmittance, which means that the MP film has the tightest structure at ph=12, because the stronger the alkalinity is, the higher the dissolution rate is, the more MP molecules participate in film formation during drying, and thus the stronger the film compactness is, the lower the transmittance is; meanwhile, the addition of the amino acid can be found to obviously reduce the water vapor transmittance of the MP film, because the amino acid can interact with protein through hydrogen bond and covalent bond to form a denser film matrix, and the hydrogen bond combination of the protein and water molecule is reduced. After adding different amino acids, the MP with added amino acid L-Pro has the highest permeability; the results of water vapor permeability indicate that the addition of amino acids under alkaline conditions can change the membrane structure, making the membrane structure denser, thereby reducing WVP, but the differences in the effects of the different amino acids are significant.
(3) Determination of mechanical Properties
The film is prepared by the following method: the alkaline MP solutions of different pH and alkaline MP-amino acid solutions of different pH in "1.MP solubility measurement" were each taken 40mL of a mixture with 0.1g of glycerol and stirred at room temperature for 1 hour, and finally the samples were poured into a polyethylene mold (diameter 9 cm) and dried at 40 ℃.
The films were measured for TS, EB and YM using a Universal tensile tester (INSTRON 5943, instron Inc., USA). The testing method comprises the following steps: the film was cut into a rectangular shape having a length of 60mm and a width of 20mm, and stretched at a stretching speed of 1mm/s with a jig distance of 30 mm. YM is obtained from the slope of the stress-strain curve, and TS and EB are calculated using the following formulas: ts=f/(l×w); eb= (L 1 -L 0 )/L 0 X 100%; wherein F represents the maximum stretching force (N) at which the film breaks; l: average thickness (mm); w: film width (mm); l (L) 1 For the length (mm) of the film after stretching, L 0 Is the initial length (mm) of the film.
The mechanical properties of the films prepared from alkaline MP solutions of different pH and alkaline MP-amino acid solutions of different pH are shown in Table 1.
TABLE 1 measurement results of mechanical properties of films prepared from alkaline MP solutions and alkaline MP-amino acid solutions having different pH values
Group of Elongation at break (%) Tensile Strength (MPa) Young's modulus (MPa) Thickness (mm)
MP-His(pH＝10) 52.3±4.5 fg 7.7±0.3 a 50.6±5.6 b 0.06±0.035 a
MP-His(pH＝11) 54.2±5.9 fg 8.7±1.6 a 45.5±4.9 b 0.12±0.012 a
MP-His(pH＝12) 78.9±1.6 ab 10.3±0.9 a 39.2±7.6 bc 0.11±0.034 a
MP-Pro(pH＝10) 40.7±8.6 gh 7.6±1.5 a 28.9±4.3 cd 0.11±0.009 a
MP-Pro(pH＝11) 56.3±7.6 efg 7.9±0.5 a 23.6±5.6 d 0.11±0.047 a
MP-Pro(pH＝12) 74.4±4.7 abc 8.2±0.7 a 18.2±2.9 d 0.09±0.001 a
MP-Lys(pH＝10) 48.5±6.5 fg 7.2±0.1 a 83.3±11. a 0.15±0.038 a
MP-Lys(pH＝11) 50.7±4.9 fg 7.4±0.4 a 87.3±4.9 a 0.12±0.067 a
MP-Lys(pH＝12) 71.9±1.1 bcde 8.8±0.4 a 87.2±3.6 a 0.08±0.042 a
MP-Arg(pH＝10) 58.6±5.6 def 7.9±0.3 a 44.7±2.6 b 0.07±0.003 a
MP-Arg(pH＝11) 73.6±1.6 abcd 8.3±1.4 a 50.6±4.6 b 0.07±0.086 a
MP-Arg(pH＝12) 87.9±2.9 a 10.7±1.9 a 51.1±6.5 b 0.07±0.004 a
MP(pH＝10) 31.2±6.2 h 1.6±0.4 b 18.8±0.4 d 0.11±0.042 a
MP(pH＝11) 46.6±1.3 fgh 1.9±1.5 b 19.5±0.3 d 0.11±0.017 a
MP(pH＝12) 59.4±4.9 cdef 2.2±0.6 b 21.1±0.9 d 0.12±0.02 a
As can be seen from table 1, under alkaline conditions, the mechanical properties of the MP film, including mechanical strength and elongation at break, are improved significantly after the addition of four different amino acids; the addition of the amino acid can improve the tensile strength of the MP film to 7-11 MPa; the elongation at break is improved from 30-60% to 40-90%, the above phenomena are mainly due to the interaction of amino acid and protein, so that the structure of the membrane material is more uniform and compact, the membrane becomes more stretch-proof, on the other hand, the influence of the pH value on the protein membrane is also obvious, the mechanical property of the membrane is increased along with the increase of the pH value, and the effective solubility of MP molecules in the membrane forming liquid is possibly increased due to the alkalinity, so that more MP molecules participate in the membrane forming in the drying process, which is beneficial to forming a more compact structure, thereby improving the mechanical property of the membrane; in addition, by comparing the mechanical properties of MP films prepared by adding L-Arg, L-Lys and L-His to those of MP films prepared by adding L-Pro after four amino acids are added, the effect of improving the mechanical properties of films by different amino acids is also greatly different.
According to the solubility measurement result, the water vapor permeability measurement result and the mechanical property measurement result, the added amino acid is finally determined to be L-Lys, L-Arg or L-His in the invention.
Example 1
Zein is available from national pharmaceutical chemicals limited; polyethylene glycol-600 (PEG-600), nano SiO 2 Are available from Shanghai microphone Lin Shenghua Co.
(one) preparation of MP solution
Mixing 100g of silver carp with 100mL of a first buffer solution (NaCl solution containing EDTA and Tris-HCl buffer with pH7.5, wherein the concentration of EDTA is 5mM, the concentration of Tris-HCl is 5mM, and the concentration of NaCl is 25 mM), grinding, centrifuging 10000 Xg for 10min, discarding the supernatant, taking the precipitate, mixing the precipitate with 500mL of a second buffer solution (NaCl solution containing EDTA and Tris-HCl buffer with pH7.5, wherein the concentration of EDTA is 5mM, the concentration of Tris-HCl is 5mM, and the concentration of NaCl is 0.1M), homogenizing, centrifuging 10000 Xg for 10min, and discarding the supernatant; suspending the precipitate in 350mL second buffer solution, filtering with gauze, centrifuging to remove supernatant, washing the precipitate with distilled water to obtain MP solution, and performing all steps at a temperature below 4deg.C;
(II) preparation of basic MP-amino acid solution
Mixing 50mL of 5mM amino acid (L-Arg) solution with 50mL of 50mg/mL MP solution, and adjusting the pH to 10 by using 5M NaOH to obtain alkaline MP-amino acid solution;
(III) preparation of silver carp myofibrillar protein-amino acid Janus membrane
Heating Zein film-forming liquid in 80 ℃ water bath for 1h, performing ultrasonic treatment, adjusting the pH to 8 by using NaOH with the concentration of 5M, magnetically stirring for 2min until the pH is stable, pouring 50mL of Zein film-forming liquid into a round plastic culture dish with the diameter of 9cm, drying at 40 ℃ for 10h to form a film, pouring 20mL of alkaline MP-amino acid solution into the round plastic culture dish, and drying at 40 ℃ for 10h to form a film to obtain an MP-amino acid Janus film; the Zein film forming liquid comprises the following components in percentage by mass: 4% Zein,2% glycerol, 3% PEG-600,1.5% nano SiO 2 50% ethanol, the balance water.
The obtained MP-amino acid Janus film is used for preserving fresh cut apples, and respectively measuring browning indexes, weightlessness rate and hardness of the fresh cut apples.
The fresh-keeping method comprises the following steps: fresh and undamaged apples (red Fuji) are cut into pieces with the size of 3cm multiplied by 1cm multiplied by 3cm, the pieces are evenly arranged in MP-amino acid Janus films and commercial PE preservative films which are packaged in the same area, meanwhile, unpackaged apples are used as blank groups, each group of fresh cut apples is stored at the temperature of 4 ℃, and relevant indexes are measured at the 0 th, 1 th, 2 nd, 3 rd and 4 th days.
(1) Determination of browning index
Color difference of freshly cut apples during storage was measured using a color difference meter (CR-20, konikama midada, usa) and recorded as L, a, b values, and before using the color difference meter, the browning index was calculated using the following formula: browning (%) = (x-0.31)/0.172×100%, where x= (a+1.75l)/(5.645 l+a-3.012 b), where: the value L is a luminance value, a is a red-green chromaticity value, and b is a yellow-blue chromaticity value.
The results of the measured browning index change are shown in fig. 3.
As can be seen from fig. 3, the browning degree of the fresh-cut apples packaged by the MP-amino acid Janus film is obviously reduced compared with that of the apples packaged by the blank control group and the PE preservative film, and the browning of the fresh-cut apples is mainly caused by the contact of oxygen and enzyme in the apples, which shows that the MP-amino acid Janus film has excellent oxygen blocking performance and has a better effect of delaying the browning of the fresh-cut apples in the storage process.
(2) Weight loss rate determination
The weight loss rate was measured by a weighing method and expressed as percent loss of fresh cut apple weight: weight loss ratio (%) = = (W) 0 -W 1 )/W 0 X 100%, where W 0 、W 1 Represents the weight of the fresh cut apples at the beginning (0 d) and at the time of measurement (1 st, 2 nd, 3 rd and 4d at 4 ℃), and the average value of 3 measurements is taken.
The change in weight loss rate of apples during storage is shown in fig. 4. The weight loss rate of fresh cut apples is related to the self respiration rate and the surface moisture evaporation rate. The rate of moisture loss depends on the pressure differential between the fresh cut apples themselves and the surrounding atmosphere and the storage temperature. Thus, the film package may limit moisture transfer. As can be seen from fig. 4, the weight loss rate of the fresh-cut apples increases with time, the weight loss rate of apples preserved by the commercial PE fresh-keeping film is minimum, the weight loss rate is only about 2.5% on the 4 th day, compared with the weight loss rate of the blank group, which is highest, the weight loss rate on the 1 st day is about 4%, the weight loss rate on the 4 th day is about 7%, and the apples have no edible value at all; the weight loss rate of the fresh-cut apples packaged by the MP-amino acid Janus film is about 5.5 on the 4 th day, which indicates that the Janus film prepared by the invention can well limit water loss and can effectively control the weight loss of the fresh-cut apples.
(3) Hardness measurement
The hardness of the freshly cut apples was measured by a fruit hardness tester (GY-2 type, ming Rui electronic technology Co., guangzhou, inc.), the hardness of the equatorial portion of the freshly cut apples was measured, and the average value of 3 measurements was taken.
The hardness change of each group of apples during storage is shown in fig. 5.
The fresh cut apples soften and exhibit a soft and spongy texture due to their aging. Therefore, hardness is one of the important indicators reflecting the quality of freshly cut apples.
Figure 5 shows the effect of different packaging films on hardness during storage of freshly cut apples. The decrease in hardness of the cut apples is associated with protein and polysaccharide degradation and microbial infestation, with each group of cut apples decreasing in hardness gradually over time. On day 2, the hardness of the cut apples of the blank group is obviously reduced, the hardness of the cut apples of other package groups is reduced at a lower speed than that of the blank group, and by day 4, the hardness of the cut apples of the blank group is reduced by 36%, which greatly influences the commercial value of the cut apples; the fresh-cut apples packaged by the MP-amino acid Janus film have a certain effect in maintaining the texture of the fresh-cut apples, which indicates that the MP-amino acid Janus film can reduce the respiratory metabolism of the fresh-cut apples in the package, thereby delaying the reduction of hardness.
Example 2
In this example, the amino acid in the amino acid solution was L-Lys, and the rest was the same as in example 1.
Example 3
In this example, the amino acid in the amino acid solution was H-His, and the rest was the same as in example 1.
Example 4
In this example, the Zein film-forming liquid contained 6% by mass of Zein, and the remainder was the same as in example 1.
Example 5
In this example, the Zein film-forming liquid contained 6% by mass of Zein, and the remainder was the same as in example 2.
Example 6
In this example, the Zein film-forming liquid contained 6% by mass of Zein, and the remainder was the same as in example 3.
Example 7
In this example, the Zein film-forming liquid contained 8% by mass of Zein, and the remainder was the same as in example 3.
Example 8
In this example, the Zein film-forming liquid contained 8% by mass of Zein, and the remainder was the same as in example 3.
Example 9
In this example, the Zein film-forming liquid contained 8% by mass of Zein, and the remainder was the same as in example 3.
(1) The MP-amino acid Janus films obtained in examples 1 to 9 were subjected to the same method for measuring Water Vapor Permeability (WVP) as the "1. Amino acid selection" method for measuring Water Vapor Permeability (WVP).
The results of the Water Vapor Permeability (WVP) measurements are shown in table 2.
TABLE 2 MP side WVP and Zein side WVP of MP-amino acid Janus membrane in examples 1-9
As can be seen from table 2, the WVP value of the MP-amino acid layer is higher than that of the Zein layer, probably due to the poor water resistance of the MP-amino acid layer, which may cause swelling during the test, which may lead to an increase in the free volume within the membrane, and the WVP value is also increased, in contrast to the lower WVP value of the Zein layer, which is due to the better water resistance of the Zein membrane, and the less varying membrane structure of the Zein layer in a humid environment; from this, it was demonstrated that when the Zein layer and the MP-amino acid layer were combined to obtain an MP-amino acid Janus film, the water resistance was improved and the water vapor permeability was reduced.
(2) Mechanical properties of MP-amino acid Janus films obtained in examples 1 to 9 were measured by the same method as in "1. Amino acid selection", and mechanical properties were measured using a Zein (6%) film alone and an MP film as a control group, and the results are shown in Table 3.
From Table 3, it can be seen that TS is improved after the MP film and the Zein film are compounded into a Janus double-layer film compared with a single-layer film, which shows that the MP film and the Zein film have a synergistic effect and can improve TS of the MP-amino acid Janus film; in addition, after the MP film and the Zein film are compounded into a double-layer film, EB is improved to some extent, which proves that the synergistic effect of the MP film and the Zein can improve the EB of the MP-amino acid Janus film.
(3) The MP-amino acid Janus films obtained in examples 1 to 3 and examples 7 to 9 were observed by a Scanning Electron Microscope (SEM).
The Scanning Electron Microscope (SEM) observation method comprises the following steps: the microstructure of the MP-amino acid Janus film surface and cross section was observed using SEM at 5.0kV voltage. Film samples were frozen with liquid nitrogen, fixed on a coupon stake, and metal sprayed to obtain a micrograph of the film at an magnification of x 200.
SEM images of MP-amino acid Janus membranes obtained in examples 1 to 3 are shown in fig. 6 to 8, and SEM images of MP-amino acid Janus membranes obtained in examples 7 to 9 are shown in fig. 9 to 11.
As can be seen from fig. 3 to 8, the microstructure of the MP-amino acid membrane is significantly different from that of the Zein membrane, and is relatively more compact, whereas the Zein membrane shows a typical porous structure; furthermore, it can be seen that there is little space between the two films, indicating that the connection between the two films is very tight.
The above-described embodiment is only a preferred embodiment of the present invention, and is not limited in any way, and other variations and modifications may be made without departing from the technical aspects set forth in the claims.

Claims (6)

1. The preparation method of the silver carp myofibrillar protein-amino acid Janus membrane is characterized by comprising the following steps of:
(one) preparation of MP solution
Mixing silver carp meat with a first buffer solution, grinding, centrifuging to remove supernatant, mixing precipitate with a second buffer solution, homogenizing, centrifuging to remove supernatant; suspending the precipitate in a second buffer solution, filtering with gauze, centrifuging to remove supernatant, and washing the precipitate with distilled water to obtain MP solution; all steps are carried out at a temperature below 4 ℃; (II) preparation of basic MP-amino acid solution
Mixing 50mL of the amino acid solution with 50mL of MP solution with the concentration of 50mg/mL, and adjusting the pH to 10-12 by using NaOH with the concentration of 5M to obtain an alkaline MP-amino acid solution; the concentration of the amino acid in the amino acid solution is 5mM, and the amino acid is L-Lys, L-Arg or L-His;
(III) preparation of silver carp myofibrillar protein-amino acid Janus membrane
Heating Zein film-forming liquid in water bath, performing ultrasonic treatment, adjusting pH to 8, pouring into a mold, drying to form film, pouring alkaline MP-amino acid solution into the mold, and drying to form film to obtain MP-amino acid Janus film.
2. The method according to claim 1, wherein in the step (one), the first buffer solution is a NaCl solution containing EDTA and Tris-HCl buffer solution with pH of 7.5, wherein the concentration of EDTA in the first buffer solution is 5mM, the concentration of Tris-HCl is 5mM, and the concentration of NaCl is 25mM; the silver carp meat is 100g, and the volume of the first buffer solution is 100mL.
3. The method according to claim 2, wherein in the step (a), the precipitate is mixed with 500mL of the second buffer; suspending the pellet in 350mL of a second buffer; the second buffer solution is a NaCl solution containing EDTA and Tris-HCl buffer solution with pH of 7.5, wherein the concentration of EDTA in the second buffer solution is 5mM, the concentration of Tris-HCl is 5mM, and the concentration of NaCl is 0.1M.
4. The preparation method of the silver carp myofibrillar protein-amino acid Janus membrane according to claim 1, wherein in the step (III), the Zein film forming liquid consists of the following components in percentage by mass: 4-8% of Zein,2% of glycerol, 3% of PEG-600,1.5% of nano SiO 2 50% ethanol, the balance water.
5. The method for preparing a silver carp myofibrillar protein-amino acid Janus film according to claim 1, wherein in the step (III), the water bath temperature is 80 ℃, and the water bath heating time is 1h; the pH was adjusted to 8 using NaOH at a concentration of 5M; pouring 50ml of Zein film forming solution into a round plastic culture dish with the diameter of 9cm, and drying for 10 hours at 40 ℃; then, 20mL of a basic MP-amino acid solution was poured thereinto and dried at 40℃for 10 hours.
6. Use of a silver carp myofibrillar protein-amino acid Janus film prepared by the preparation method of the silver carp myofibrillar protein-amino acid Janus film according to any one of claims 1 to 5 in fresh food preservation.
CN202310845927.4A 2023-07-11 2023-07-11 Preparation method and application of silver carp myofibrillar protein-amino acid Janus membrane Active CN116970281B (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103087355A (en) * 2012-12-29 2013-05-08 浙江工业大学 Tea polyphenol-containing chitosan-minced fillet protein composite film and preparation method thereof
CN110772671A (en) * 2019-10-17 2020-02-11 东华大学 Janus membrane for bone repair and preparation method thereof
CN111647275A (en) * 2020-07-21 2020-09-11 华中农业大学 Preparation method of edible composite membrane of fish myofibrillar protein

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103087355A (en) * 2012-12-29 2013-05-08 浙江工业大学 Tea polyphenol-containing chitosan-minced fillet protein composite film and preparation method thereof
CN110772671A (en) * 2019-10-17 2020-02-11 东华大学 Janus membrane for bone repair and preparation method thereof
CN111647275A (en) * 2020-07-21 2020-09-11 华中农业大学 Preparation method of edible composite membrane of fish myofibrillar protein

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