阅读说明：本技术 一种纤维素纳米晶体-乳清分离蛋白复合热凝胶的制备方法 (Preparation method of cellulose nanocrystal-whey protein isolate composite thermal gel ) 是由 欧阳韶晖 *** 刘英男 邢仲芳 郭进安 徐怀德 于 2019-09-20 设计创作，主要内容包括：本发明涉及食品加工技术领域,具体涉及一种纤维素纳米晶体-乳清分离蛋白复合热凝胶的制备方法。本发明制备方法的步骤为：1)制备纤维素纳米晶体-乳清分离蛋白混合溶液；2)制备纤维素纳米晶体-乳清分离蛋白复合热凝胶。本发明制备方法可提高乳清分离蛋白复合热凝胶的保水性、强度和弹性。(The invention relates to the technical field of food processing, in particular to a preparation method of cellulose nanocrystal-whey protein isolate composite thermal gel. The preparation method comprises the following steps: 1) preparing a cellulose nanocrystal-whey protein isolate mixed solution; 2) preparing the cellulose nanocrystal-whey protein isolate composite thermal gel. The preparation method can improve the water retention, strength and elasticity of the whey protein isolate composite thermal gel.)

1. A preparation method of cellulose nanocrystal-whey protein isolate composite thermal gel is characterized by comprising the following steps: the method comprises the following steps:

1) preparation of cellulose nanocrystal-whey protein isolate mixed solution

Uniformly mixing the cellulose nanocrystals, the whey protein isolate and deionized water in proportion, adjusting the pH value of the mixed solution to 5-9, fully stirring, standing for 10-12 hours at 4 ℃ to completely hydrate the protein, and obtaining a cellulose nanocrystal-whey protein isolate mixed solution;

2) preparation of cellulose nanocrystal-whey protein isolate composite thermal gel

And (2) transferring 8-10 g of the cellulose nanocrystal-whey protein isolate mixed solution obtained in the step 1) to a small beaker of 10mL, sealing the beaker by using a preservative film, heating in a water bath, rapidly cooling in an ice-water bath for 1-2 h, refrigerating and standing to obtain the cellulose nanocrystal-whey protein isolate composite thermal gel.

2. The method for preparing the cellulose nanocrystal-whey protein isolate composite thermal gel according to claim 1, wherein the method comprises the following steps: the mass concentration of the whey protein isolate in the mixed solution in the step 1) is 10.5% (w/v), and the mass concentration of the cellulose nanocrystals is 0.25-1.0% (w/v).

3. The method for preparing the cellulose nanocrystal-whey protein isolate composite thermal gel according to claim 1, wherein the method comprises the following steps: the pH value in step 1) is adjusted by 1M hydrochloric acid solution and 1M sodium hydroxide solution.

4. The method for preparing the cellulose nanocrystal-whey protein isolate composite thermal gel according to claim 1, wherein the method comprises the following steps: the step 1) of fully stirring is to perform magnetic stirring for 2-4 hours at the temperature of 25 ℃.

5. The method for preparing the cellulose nanocrystal-whey protein isolate composite thermal gel according to claim 1, wherein the method comprises the following steps: and (3) heating the water bath in the step 2) in a water bath at 85-95 ℃ for 30-40 min.

6. The method for preparing the cellulose nanocrystal-whey protein isolate composite thermal gel according to claim 1, wherein the method comprises the following steps: and (3) refrigerating and standing for 10-12 hours at 4 ℃.

The technical field is as follows:

the invention relates to the technical field of food processing, in particular to a preparation method of cellulose nanocrystal-whey protein isolate composite thermal gel.

Secondly, background art:

cellulose is formed by connecting beta-D-glucose molecules through beta- (1-4) glycosidic bonds, and is a polysaccharide which is most widely distributed and abundant in nature. With the vigorous development of nanotechnology, cellulose nanocrystals prepared from various fiber resources and their applications are being continuously attracted. Due to the unique physical and chemical properties of the cellulose nanocrystals, including high length-diameter ratio and crystallinity, large specific surface area, rich hydroxyl groups, hydrogen bonds, safety, no toxicity, good biodegradability and biocompatibility, the cellulose nanocrystals are widely applied in various fields. More interestingly, naturally derived cellulose nanocrystals also show broad application prospects in the food field, including: stabilizing pickering emulsions, improving rheological and emulsifying properties, as a functional food ingredient or packaging material, and regulating protein digestion and gelling properties.

The whey protein isolate mainly comprises beta-lactoglobulin (60-70%) and a small part of alpha-lactalbumin and bovine serum albumin. In addition to having a high nutritional value and biological activity, whey protein isolate is also considered to be an ideal ingredient for modifying the processing characteristics of food due to its outstanding functionality. Among them, the ability of thermally induced gels is one of its most important functionalities, as it determines to a large extent the final texture and organoleptic quality of the food product. However, the whey protein isolate gel alone has disadvantages of sensitivity to changes in external environment (such as salt ion concentration, pH, temperature, etc.), structural instability, etc., thereby greatly limiting its application in the food field. Therefore, improving the stability of whey protein isolate gel systems is a key to the design and development of new food products.

The interaction of proteins and polysaccharides provides an effective strategy for enriching the functionality of protein gels and for expanding their applications. It has been found that insoluble dietary fibers, including cellulose, can improve the gel properties of protein gels by inducing the formation of stable network structures. Considering the nano-size effect of cellulose nanocrystals and their unique physicochemical properties, it would be very interesting to study the effect of cellulose nanocrystals on protein gel properties. In addition, the introduction of cellulose nanocrystals can also balance the dietary nutrition of the protein gel system. However, to our knowledge, no relevant report on whey protein isolate thermal gels complexed by cellulose nanocrystals has been found so far.

Third, the invention

The invention provides a preparation method of a cellulose nanocrystal-whey protein isolate composite thermal gel, which can improve the water retention, strength and elasticity of the whey protein isolate composite thermal gel.

In order to achieve the purpose, the invention adopts the technical scheme that:

a preparation method of cellulose nanocrystal-whey protein isolate composite thermal gel is characterized by comprising the following steps: the method comprises the following steps:

1) preparation of cellulose nanocrystal-whey protein isolate mixed solution

Uniformly mixing the cellulose nanocrystals, the whey protein isolate and deionized water in proportion, adjusting the pH value of the mixed solution to 5-9, fully stirring, standing for 10-12 hours at 4 ℃ to completely hydrate the protein, and obtaining a cellulose nanocrystal-whey protein isolate mixed solution;

2) preparation of cellulose nanocrystal-whey protein isolate composite thermal gel

And (2) transferring 8-10 g of the cellulose nanocrystal-whey protein isolate mixed solution obtained in the step 1) to a small beaker of 10mL, sealing the beaker by using a preservative film, heating in a water bath, rapidly cooling in an ice-water bath for 1-2 h, refrigerating and standing to obtain the cellulose nanocrystal-whey protein isolate composite thermal gel.

The mass concentration of the whey protein isolate in the mixed solution in the step 1) is 10.5% (w/v), and the mass concentration of the cellulose nanocrystals is 0.25-1.0% (w/v).

The pH value in step 1) is adjusted by 1M hydrochloric acid solution and 1M sodium hydroxide solution.

The step 1) of fully stirring is to perform magnetic stirring for 2-4 hours at the temperature of 25 ℃.

And (3) heating the water bath in the step 2) in a water bath at 85-95 ℃ for 30-40 min.

And (3) refrigerating and standing for 10-12 hours at 4 ℃.

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

1) the cellulose nanocrystal-whey protein isolate composite thermal gel has the water retention of more than 85%, the gel strength of more than 35g, the storage modulus of more than 4000Pa, and is higher than that of the gel formed by whey protein isolate alone;

2) the preparation process of the whey protein isolate gel is simple, the process is controllable, the whey protein isolate gel is safe and environment-friendly, and the whey protein isolate gel with higher stability is formed;

3) the invention provides a new visual angle for the innovative application of the cellulose nanocrystals and the whey protein isolate in the food industry;

4) the cellulose nanocrystals of the present invention can also balance the dietary nutrition of the protein gel system.

Fourthly, explanation of the attached drawings:

FIG. 1 is a macroscopic view of cellulose nanocrystal-whey protein isolate composite thermal gels at different concentrations in example 3; CNC is cellulose nanocrystal;

FIG. 2 is a graph showing the water retention of cellulose nanocrystal-whey protein isolate composite thermal gels at different concentrations in example 3;

FIG. 3 is a graph showing gel strength of cellulose nanocrystal-whey protein isolate composite thermal gels at different concentrations in example 3;

FIG. 4 is the storage modulus of the cellulose nanocrystal-whey isolated protein complex thermal gel of example 3 at different concentrations; (a) is the storage modulus during the temperature rise; (b) is the storage modulus during the cooling process.

FIG. 5 is the scanning electron microscope image of the cellulose nanocrystal-whey protein isolate composite thermal gel of different concentrations in example 3.

The fifth embodiment is as follows:

in order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.