CN115413731B - High-water-holding-capacity gluten protein-based plant meat and manufacturing method thereof - Google Patents

Abstract

The invention discloses a high-water-holding capacity gluten-based plant meat and a preparation method thereof. The high-water-holding-capacity gluten-based plant meat prepared by the method has good chewiness, hardness, elasticity and viscosity, the water holding capacity is obviously improved, the texture is obvious, and the fiber structure similar to animal meat appears, so that the expected taste is obtained.

Description

High-water-holding-capacity gluten protein-based plant meat and manufacturing method thereof

Technical Field

The invention relates to the technical field of food processing, in particular to high-water-holding-capacity gluten protein-based plant meat and a preparation method thereof.

Background

Wheat gluten (Wheat gluten protein, WGP) commonly called wheat gluten is wheat gluten powder which is obtained by taking grains such as wheat and the like as raw materials, carrying out a series of scientific processing and treatment, washing off starch and other soluble substances in the wheat flour, and drying the residual wheat gluten powder, wherein the protein content is higher than 80%, and the wheat gluten powder contains trace lipid, mineral substances, carbohydrate and the like; the amino acid is complete in variety, mainly contains glutamic acid, proline and the like, is a plant protein source with rich nutrition, high quality and low cost, and has unique properties which are not available in other plant proteins: has viscoelasticity, expansibility, thermal solidification, gluten network formation and other properties, and has certain flavor characteristics: light mellow taste or cereal taste. Wheat gluten can be classified into four main types according to solubility in various solvents, albumin dissolved in water and dilute salt solution, globulin insoluble in water but dissolved in 10% nacl solution, prolamin (Glianin) dissolved in 70% -90% ethanol solution, and glutenin (Glutenin) dissolved in dilute acid and dilute alkali solution, the latter two proteins being the main proteins of wheat gluten. The characteristic of poor water solubility of the wheat gluten can be seen by the composition of the wheat gluten, which is not beneficial to the expansion application of the wheat gluten in the food field.

The vegetable meat is food which takes vegetable protein as a main raw material and simulates animal meat fiber and mouthfeel and texture after certain processing and treatment. The vegetable meat has wide protein source, low cost and mature processing technology, but has a certain gap with animal meat in the aspects of texture, flavor, color and the like. Most of vegetable proteins used in the vegetable meat products at home and abroad are soybean proteins, peanut proteins or complexes of the soybean proteins and wheat gluten, and the wheat gluten is rarely used as a main raw material of the vegetable meat, because the wheat gluten has poor water solubility and is easy to form a gluten network due to the self structural characteristics, the vegetable meat or sausage, meat balls and the like prepared by using the wheat gluten as the main raw material have poor water holding capacity, short shelf life and poor texture, and the advantages of the high-quality wheat gluten protein cannot be fully exerted.

In order to change the above conditions, the present inventors have modified the wheat gluten by various treatments, and in the chinese patent of the application, publication No. CN114680226a, the present inventors have improved the solubility and emulsification properties of the gluten, and after the gluten solution is heat-treated in combination with pH cycle treatment, the disulfide bonds of the gluten molecules are broken, the content of free thiol is increased, the surface hydrophobicity is increased, and the particle size is reduced, so that the solubility and emulsification properties of the gluten are both remarkably improved. However, the plant meat directly prepared by the modified gluten protein according to the conventional preparation method of the plant meat is still not ideal in water retention, texture and the like, and has a certain difference from the animal meat in taste.

Disclosure of Invention

The invention aims to develop a preparation method of gluten-based plant meat, which further changes the structural characteristics of wheat gluten by combining a specific preparation process, so that the water holding capacity of the gluten-based plant meat is obviously improved, and the texture is obviously improved.

Based on the above purpose, the invention adopts the following technical scheme:

A method for producing high water holding capacity gluten protein based plant meat, the method comprising the steps of:

(1) Adding the modified gluten into the natural gluten according to a certain mass ratio, uniformly mixing, and adding a certain amount of water to form a high-moisture gluten system;

(2) And (3) placing the obtained high-moisture gluten protein system in a double-screw extruder, and extruding under high-temperature and high-pressure conditions to obtain the high-water-holding-capacity gluten protein-based plant meat.

According to the preparation method of the high-water-holding-capacity gluten-based plant meat, the modified gluten protein and the natural gluten protein are mixed according to a certain proportion to form a high-water-content gluten protein system, the structural characteristics of the wheat gluten protein are changed, and double-screw extrusion is performed under the high-temperature and high-pressure conditions, so that the water holding capacity of the gluten-based plant meat is remarkably improved, and the texture is remarkably improved.

In one embodiment, the modified gluten protein of step (1) is prepared by the following method:

Step a, dissolving gluten protein in distilled water at 20-30 ℃ to prepare a gluten protein water system;

step b, adopting pH circulation and heat treatment to the gluten protein water system, specifically, firstly adjusting the gluten protein water system to be alkaline by using an alkaline solution, stirring after heating treatment, and then adjusting the gluten protein water system to be neutral by using an acidic solution, and collecting the gluten protein water system after treatment;

and c, centrifuging the collected gluten protein water system, and taking supernatant for freeze drying to obtain the modified gluten protein.

In one embodiment, the modified gluten addition in step (1) is 10% by mass of the natural gluten.

In one embodiment, the mass of water added in step (1) is 40% of the total mass of gluten protein after mixing.

In one embodiment, the extrusion conditions of the twin-screw extruder in step (2) are as follows: screw rotation speed: 150r/min, 40% of water and the sleeve temperature: zone I: 65 ℃, zone ii: 90 ℃, zone iii: 135 ℃, zone iv: 165 ℃, zone v: 130℃and a die temperature of 120 ℃.

The invention also provides the high-water-holding-capacity gluten protein-based plant meat obtained by the preparation method.

Compared with the prior art, the invention has the following advantages:

According to the invention, the modified gluten is added into the natural gluten and uniformly mixed to form a high-moisture gluten system, and the high-water-holding-capacity gluten-based plant meat is prepared by extruding through a double-screw extruder, so that the high-water-holding-capacity gluten-based plant meat has good chewiness, better hardness, elasticity and viscosity, the water holding capacity is obviously improved, and an obvious animal meat-like fiber structure appears on the texture, so that the expected taste is obtained.

Drawings

FIG. 1 is a graph showing the texture characteristics of four different sets of modified gluten additions extrudates of the examples;

FIG. 2 is a graph showing the comparison of the water retention of extrudates of four different modified gluten additions in the examples;

FIG. 3 is a graph showing the comparison of the free thiol content of extrudates of four different modified gluten additions in the example;

FIG. 4 is a graph comparing the endogenous fluorescence spectra of four different sets of modified gluten addition extrudates in the example;

FIG. 5 is a microscopic image of extrudates of four different sets of modified gluten additions in the examples;

FIG. 6 is a graph showing the comparison of moisture profiles of four different sets of modified gluten addition extrudates in the examples.

Detailed Description

The present invention will be described in further detail with reference to the following embodiments in order to make the above objects, features and advantages of the present invention more comprehensible. It should be understood that the detailed description is presented by way of example only and is not intended to limit the invention.

Example 1

Protein sample preparation:

15g of gluten protein is added into 500mL of distilled water at room temperature, the pH of the gluten protein is regulated to 12 by using 1mol/L NaOH solution, the mixture is subjected to water bath for 30min at 80 ℃, magnetic stirring is carried out for 1h, then the pH is regulated to 7 by using 1mol/L HCl solution, magnetic stirring is carried out for 1h, centrifugation is carried out for 10min at 20 ℃ under 7000g centrifugal force, the supernatant fluid is poured into a culture dish and placed at-80 ℃ for prefreezing for 12h, and then the mixture is frozen and dried for 48h, and the powder obtained by freeze drying is the pH modified gluten protein sample.

Example two

Preparation of high-water-holding-capacity gluten protein-based plant meat:

Four sets of samples were set: the modified gluten was added in a gradient manner to prepare 30% and 50% groups in order, with 50g of natural gluten being 0% group, i.e., control group, 5g of modified gluten in example one and 45g of natural gluten being 10% group. The four groups of samples are fully and uniformly mixed, and are added with 40 percent deionized water to form a high-moisture system and then extruded. Adopting an experimental bench double-screw extruder for extrusion, wherein extrusion parameters are set as follows: the screw rotating speed is 150r/min, and the temperatures of the five-section sleeve areas are respectively set as follows: 65 ℃, 90 ℃, 135 ℃, 165 ℃, 130 ℃ and die temperature 120 ℃. The extruded extrudate samples were cooled at room temperature and used to determine the subsequent index after cooling.

Example III

Texture measurement:

Using P/2 probe, predicted speed: 2mm/s, test speed: 1mm/s, post test speed: 10mm/s, strain 50% and trigger force 15g. Since the extrusion caliber of the extruder used was fixed at 3.00mm, no additional change was made to the shape of the extruded sample. The four extrudates (0%, 10%, 30%, 50%) obtained by extrusion were measured for hardness, elasticity, tackiness, and chewiness. Predicted speed: 2mm/s, test speed: 1mm/s, post test speed: the tensile strength was measured at a tensile distance of 40mm at 10 mm/s. Each index was repeated more than 5 times for each set of samples.

( Wherein the tensile strength is in units of N/mm ²; f is the maximum force born by the sample when the sample breaks, N; a is the width of the sample, mm; b is the thickness of the pattern, mm )

Texture characteristics (hardness, elasticity, tackiness, chewiness, tensile Strength)

Texture characteristics are complex properties influenced by multiple factors, determined by the composition and structure of food, and are visual indicators for evaluating plant meat quality.

As shown in fig. 1, the hardness of the extrudate increases significantly with increasing amounts of modified gluten addition, 10%, 30% and 50% groups are all significantly higher than the control group, and the hardness of the extrudate is maximum when the modified gluten addition amounts reach 10% and 30%; the extrudate elasticity showed the opposite change, decreasing with increasing modified wheat gluten addition, with the remaining three groups being significantly lower than the control group. Masticatory properties are also closely related to hardness and elasticity, both of which have an influence on masticatory properties. It can be seen from fig. 1-C that the 10% group has the highest chewiness and the best chewiness, which is the result of its higher hardness and elasticity combined. The viscosity of the extrudate then tends to increase and decrease with increasing amounts of modified gluten, which may be closely related to the water retention of the extrudate. The tensile strength and hardness of the extrudate have the same trend, and the extrudate is probably due to the fact that hydrogen bonds, covalent bonds and the like are formed between the modified gluten protein and the natural gluten protein macromolecules, so that a complex network structure is formed, the flexibility of the protein macromolecules is increased, the secondary structure of the protein macromolecules is more stable, the stress is more concentrated, the tensile strength and the hardness are increased, the elasticity is reduced, the modified gluten protein is loose in molecular structure after pH circulation, interaction with the natural gluten protein is easier to form, and the hardness, the elasticity and the tensile strength are related to the addition amount of the modified gluten protein to a certain extent.

The results show that the gluten extrudate has the highest chewiness, best chewiness, hardness, elasticity and viscosity at a higher level at 10% modified gluten.

Example IV

Water retention measurement:

The resulting four extruded (0%, 10%, 30%, 50%) freeze-dried samples (2.0 g) were mixed with 10mL deionized water in a centrifuge tube and left at 25 ℃ for 0.5 hours. Then, the mixture was centrifuged at 10,000Xg for 15min, the supernatant was removed, and the total weight of the centrifuge tube and the sample was weighed. Three replicates were performed for each sample and averaged. The water holding capacity is calculated using the following formula:

WHC (%) = (m ₃ -m ₂ -m ₁) ×100

(Wherein m ₁ is the mass g of the sample, m ₂ is the mass g of the centrifuge tube, and m ₃ is the total mass g of the centrifuge tube and the sample after removal of the supernatant)

Water holding capacity

The water holding capacity is the capacity of protein to retain water (against gravity) in protein tissue after sufficient water is absorbed by the protein and centrifuged, and is critical to the properties of the sample, such as texture and color.

As shown in fig. 2, the water holding capacity of the gluten extrudate showed a trend of increasing and decreasing with increasing amount of modified gluten. The water holding capacity of 10% and 30% is 282.4% and 266%, respectively, which are 68.4% and 52% higher than that of the control group (p < 0.05). This is probably because the wheat gluten is subjected to pH cycle treatment, the gluten structure is loose, insoluble parts such as hydrophobic groups and hydrophobic amino acids are removed by exposure to a solvent, and hydrophilic groups are also exposed, so that the contact area of hydrophilic groups and water molecules is increased, the absolute number of water molecules contacted is increased, and the solubility is increased. The protein molecules are denatured and recombined to form a new protein secondary structure and a complex three-dimensional network by extrusion of a double screw extruder, so that the water holding capacity of the protein secondary structure is remarkably improved. The water holding capacity of the 50% group is only 127% at the minimum, which is probably due to the fact that when the modified gluten with a stretched structure is added to a certain amount, a compact and porous network structure cannot be formed with the natural gluten, the interception capacity of water molecules is poor, and the interaction capacity of the modified gluten and the natural gluten after being mixed and extruded in a ratio of 1:1 is weak, so that the water molecules cannot be retained, and the 50% group is the weakest in water holding capacity and low in viscosity.

The results show that the 10% group gluten protein extrudate has a water holding capacity of 282.4%, and the stronger the water holding capacity, the higher the organization degree of the product, and the extrudate has a higher organization degree when the modified gluten protein addition amount reaches 10%.

Example five

Determination of free thiol content:

(1) And (3) preparation of a reagent:

4.16g of Tris (hydroxymethyl) aminomethane (Tris), 2.76g of glycine and 0.48g of disodium ethylenediamine tetraacetate (EDTA) were weighed into 400mL of deionized water, and the pH was adjusted to 8.0 with a hydrochloric acid solution to obtain TGE reagent (Tris-glycine-EDTA buffer).

(2) Test procedure

Four extrudates (0%, 10%, 30% and 50%) obtained by extrusion were pre-frozen at-80 ℃ for 12 hours, vacuum freeze-dried for 48 hours, and after grinding, the solid powder was dissolved in Tris-Gly buffer (containing 0.09M glycine, 0.086M Tris and 1.2mM EDTA) with ph=8.0, the resulting sample solution concentration was 0.5%, reacted in a water bath at 25 ℃ for 0.5 hours, centrifuged at 8000r/min for 15 minutes, the supernatant and DTNB were mixed at a ratio of 100:1, and after standing for 15 minutes, absorbance values were measured at 412nm wavelength, the buffer was used as a blank control, and the measurement was repeated 3 times or more for each group of samples. The free mercapto content is calculated as follows:

SH＝[(10⁶/(1.36×10⁴))×A₄₁₂×D]/C

In the above formula, the unit of the free mercapto group content is. Mu. Mol/g. Wherein 1.36×10 ⁴ is the molar extinction coefficient a ₄₁₂ of the DTNB solution, i.e. the absorbance value at 412 nm; d is dilution multiple; c is the concentration of the sample solution (mg/mL).

As shown in fig. 3, the free thiol content of the four-group extrudate (0%, 10%, 30%, 50%) samples increased with increasing amounts of modified gluten added, with the free thiol content being up to 0.27 μmol/g when the addition reached 50% and significantly higher than the control (p < 0.05) and 10%, 30%. Whereas the free thiol content of the 10%, 30% group was also significantly higher than that of the control group (p < 0.05), but the free thiol content was only 0.125. Mu. Mol/g.

The results showed that the 10%, 30% group free thiol content did not decrease and that the modified gluten protein did not reform disulfide bonds with the natural gluten protein during extrusion, which also indicated from the side that disulfide bonds were not important interactions for the gluten protein extrudate to form fibrous structures, nor did the increase in extrudate water retention be a result of the interconversion between free thiol and disulfide bonds.

Example six

Endogenous fluorescence intensity determination:

Four extrudates (0%, 10%, 30% and 50%) obtained by extrusion were pre-frozen at-80℃for 12 hours, vacuum freeze-dried for 48 hours, and the obtained solid powder was dissolved in phosphate buffer solution (PBS 0.1mol/L, pH =7.0) to prepare a diluent having a protein content of 0.25mg/mL, and centrifuged at 800 r/min for 15 minutes with shaking at room temperature, and the supernatant was collected. The test was performed using a fluorescence spectrophotometer under the following conditions: the excitation wavelength is 260nm, the scanning range is 330-450nm, the scanning speed is 240nm/min, and the slit width is 5nm.

As shown in fig. 4, the four extrudates (0%, 10%, 30%, 50%) all had maximum emission wavelengths (λmax) around 340nm, the red shift was not significant, the fluorescence intensity increased with increasing modified gluten protein addition, the fluorescence intensity control was lowest, and the 50% group was highest. This may be due to the extremely basic conditions of the pH cycling process exposing a portion of the endogenous chromophore of the gluten molecule to the polar solvent, such that the modified gluten endogenous chromophore is reduced, but the protein structure is loose, leaving the remaining chromophore exposed to the protein surface. The higher the fluorescence intensity, the more intense the protein conformation changes, and the result shows that 10 percent and 30 percent of the extrudate modified gluten proteins and the natural gluten proteins form new protein structures under the extrusion action, and the protein conformation is moderately changed; the 50% of the group extrudate protein conformation changed drastically exposing more chromophores and hydrophobic groups.

Example seven

Microstructure measurement:

four extrudates (0%, 10%, 30%, 50%) obtained by extrusion were pre-frozen at-80℃for 12 hours, vacuum freeze-dried for 48 hours, milled, and then the sample sections were gold coated at 10ma for 5 minutes, and then observed with a field emission scanning electron microscope at 5.0kv and magnification of 10000X.

As shown in fig. 5, the four extrudate groups (0%, 10%, 30%, 50%) are closely packed in layers and blocks, and the fibrous structure similar to animal meat is not seen, and the porous structure is distributed on part of the surface of the tissue, but the pores are more dispersed, the number is smaller, and the pore diameter is smaller. The 10% group extrudate has a compact tissue structure, is spongy, has a fibrous structure similar to animal meat, has a large number of porous structures distributed on the tissue surface, has dense pore distribution and different pore sizes, but has larger overall size compared with the control group. The 30% group extrudate has smooth tissue structure, no fibrous structure similar to animal meat is seen, and the surface of the tissue is distributed with a large number of porous structures with larger pore diameters. The tissue structure of 50% group extrudate is compact and smooth, the surface of the tissue is distributed with porous structures, but the quantity is small, and the pore diameter is small.

The result shows that the modified gluten protein is added into the natural gluten protein according to the proportion of 10 percent, and is extruded by a double screw extruder, the structure of the extrudate is compact, the extrudate is spongy, and the fibrous structure which is obviously similar to animal meat appears. The rest of the addition ratio has no fiber orientation and no fiber structure similar to animal meat is seen.

Example eight

Moisture distribution measurement:

Four extrudates (0%, 10%, 30%, 50%) obtained by extrusion were wrapped with polytetrafluoroethylene (Teflon) tape to prevent water loss and placed in a glass tube having an inner diameter of 25 mm. Magnetic Resonance Imaging (MRI) image analysis is then performed using a multi-slice spin echo (MSE) sequence. The test conditions were as follows, spin echo time was 9.5ms; the resampling time is 1000ms; the number of resampling is 8, and the t 2-weighted gray scale image of all samples is subjected to pseudo color processing.

In general, the background of a pseudo-color image of nuclear magnetic resonance is dark blue, and when the color of a sample changes from green to red, the density of hydrogen protons increases, and the moisture content increases; the appearance of partial yellow and red of the sample image indicates that the water distribution of the sample is uneven, and the whole sample image is yellow-green, which indicates that the water distribution is relatively even. As shown in fig. 6, the four control extrudate groups (0%, 10%, 30%, 50%) appeared to be partially red, with high moisture content but uneven distribution; the images of 10 percent and 30 percent of groups are in yellow-green color as a whole, and the water content of 10 percent of groups is slightly higher than that of 30 percent of groups but the water distribution is uniform; the 50% group moisture distribution was uniform but the moisture content was low.

The result shows that the modified gluten protein is added into the natural gluten protein according to the proportion of 10 percent and extruded by a double screw extruder, the moisture of the extrudate is uniformly distributed, the moisture content is moderate, and the modified gluten protein has higher organization degree and better texture characteristics.

The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.

Claims (2)

1. A method for producing high water holding capacity gluten protein based plant meat, characterized in that the method comprises the following steps:

(1) Adding modified gluten into natural gluten according to a certain mass ratio, uniformly mixing, adding a certain amount of water, wherein the mass of the water is 40% of the total mass of the mixed gluten, so as to form a high-moisture gluten system, and the mass ratio of the added modified gluten is 10% of that of the natural gluten;

(2) The obtained high-moisture gluten protein system is placed in a double-screw extruder to be extruded under the high-temperature and high-pressure conditions, and the extrusion conditions of the double-screw extruder are as follows: screw rotation speed: 150r/min, 40% of water and the sleeve temperature: zone I: 65 ℃, zone ii: 90 ℃, zone iii: 135 ℃, zone iv: 165 ℃, zone v: 130 ℃ and the die head temperature is 120 ℃, so as to prepare the high-water-holding-capacity gluten-based plant meat;

the modified gluten protein in the step (1) is prepared by the following method:

Step a, dissolving gluten protein in distilled water at 20-30 ℃ to prepare a gluten protein water system;

step b, adopting pH circulation and heat treatment to the gluten protein water system, specifically, firstly adjusting the gluten protein water system to be alkaline by using an alkaline solution, stirring after heating treatment, and then adjusting the gluten protein water system to be neutral by using an acidic solution, and collecting the gluten protein water system after treatment;

and c, centrifuging the collected gluten protein water system, and taking supernatant for freeze drying to obtain the modified gluten protein.

2. The high water holding capacity gluten-based plant meat obtained by the method according to claim 1.