Development Of Paper-based/Silica Sol/Polyvinyl Alcohol Color-change Composite Film And Study On Water Holding Capacity Testing Method Of Meat

Meat not only has high nutritional value,but also has a beautiful color and delicious taste.The water holding capacity is one of the important factors influencing the quality of meat.The higher the water holding capacity is,the more tender and elastic the meat is.Therefore,researching a fast,efficient,and low-cost system for water holding capacity detection is of great significance for meat produce,process,and sales.This paper aims to quickly test the water holding capacity of pork and beef and develop a paper-based/silica sol/polyvinyl alcohol discoloration composite film.The properties and service life of the composite membrane were studied.And a model for predicting the water holding capacity grade of the system based on Fisher's discrimination was established.It provided a certain theoretical basis for the study of the water holding capacity detection method of meat.(1)Development of paper-based/silica sol/polyvinyl alcohol discoloration composite film for water holding capacity testing of meat products.Based on the principle that cobalt chloride combines with water to form different hydrates and show different colors,air-laid paper was used as the paper base,silica sol was used as the main film-forming liquid,glycerin was used as a plasticizer,polyvinyl alcohol was used as a binder and cobalt chloride as a color developer.Paper-based/silica sol/polyvinyl alcohol discoloration composite film for the water holding capacity testing of meat products was developed.Compared and analyzed the color changing time of composite film prepared by immersion coloring and mixed coloring.The mixed coloring was determined as the best coloring method.The drying time required for the preparation of the composite film was studied.The optimal drying time was determined to be 3 hours based on the color parameter R.Through single factor test and response surface optimization test,the optimal preparation process of the composite film was determined as follows: 56% glycerin was added into 11.8 mL silica sol and mixed them evenly.The pH of solution was adjusted with ethyl acetate.Then 5.3 mL 5% polyvinyl alcohol and 14% cobalt chloride were added successivelyand mixed them evenly.The 22 mL mixture was poured into a petri dish which covered with air-laid paper and dried it in an oven at 95? for 3 hours.(2)Characterization of structure,properties and life analysis of paper-based/silica sol/polyvinyl alcohol composite film.The molecular structure,properties and functions of the components(silica sol,glycerol,polyvinyl alcohol)of the composite film were analyzed.The film-forming mechanism of the composite film was studied.The properties of composite film and single-layer film,such as film formation,texture,light transmittance,microstructure,film thickness,mechanical strength and water solubility were characterized and analyzed.The results showed that the composite film based on air-laid paper had better properties.The thickness of the composite membrane was 0.47 mm,the tensile strength was 7.72 MPa,the elongation at break was 28.54% and the water solubility was 42.56%.The service life of the composite film was studied.The storage time of the composite film was determined to be 3 weeks according to the standards of inner membrane thickness,elongation at break,tensile strength,water solubility and color.The results showed that the color of composite film changes completely after 12 days storage but composite film changes little within 12 days.And the color changes obviously after21 days,so the service life of the composite film is 21 days.(3)The method of water holding capacity detection of different meat by composite membrane was study.The water holding capacity values of 50 groups of pork samples and 50 groups of beef samples were measured by pressure method and classified.The results showed that the water holding capacity values of beef were mostly between 0.71 and 0.90.The water holding capacity values of pork were mostly between 0.61 and 0.90.Taking the color parameters R(red),G(green)and B(blue)of the composite film as indicators,the single factor test was carried out on the adhesion time of the composite film and the meat sample to be tested,and the optimal adhesion time of the composite film was determined to be 3 minutes.The color parameters R,G and B of the composite film collected by the intelligent color sensor were used as independent variables.And the water holding capacity grade measured by the pressure method was used as grouping variable.30 groups of pork samples and 30 groups of beef samples were randomly selected.The Fisher discriminant model for prediction the water holding capacity grades of pork and beef were constructed respectively by SPSS,and the other 20 groups were used respectively.The accuracy of the twomethods is 90% and 85% respectively.