Preparation And Physicochemical Properties Of Soy Peptide-Carrageenan Composite Film

Edible film, including membrane protein, polysaccharide film, starch and composite film, is a kind of green packaging materials. Composite film comprises the advantages of unitary film material and is now a hot research.This paper studied the enzymatic process of soy protein isolate and the molecular weight of soy peptide. On this basis, edible filmswere prepared from soybean peptides and carrageenan. The effects of different plasticizers on the film properties (tensile strength, elongation at break, water vapor permeability, the oxygen permeability thickness, color and transparency) were studied and the edible film formulation was optimized. What is more, the effects of montmorillonite on composite film properties were studied. Also studied film-forming intermolecular interactions by infrared spectroscopy and thermal analysis(TGA).Enzymatic process:The effect of substrate concentration, enzyme dosage, reaction temperature, reaction time and the initial pH value on the degree of hydrolysis were studied and the best of hydrolysis condition was substrate concentration of 10%, enzyme dosage of 5%, reaction time 5h, initial pH 9.0, reaction temperature 60 ℃. Tricine-SDS-PAGE electrophoresis showed a relative molecular weight of soybean peptide were 20.1kDa following. The scanning electron micrographs showed that three-dimensional structure of soy protein isolate damaged and the degradation has been very good.Research plasticizer:The effects of glycerol (GLY), polyethylene glycol (PEG), sorbitol (PFG) and propylene glycol (PPG) on the properties of soy peptide-carrageenan composite films were researched and compared. The film-forming molecules compatibility of four plasticizers were studied by TGA analysis.Formulation process research:The effect of the addition amount of soybean peptide, the addition amount of glycerin and added amount of carrageenan on the composite film properties were studied. The best of hydrolysis condition was the added amount carrageenan 3%, the added amount soybean peptide 2% and the added amount glycerin 1%. The network architecture of soybean peptide analysis - carrageenan composite film was carrageenan by infrared spectroscopy and the bubble of composite membrane was less than carrageenan film and the surface of composite membrane was smoother by Atomic Force Microscopeanalysis.The effect of montmorillonite on composite film properties:The effect of the amount of montmorillonite on the composite film properties and the adsorption intercalation of soybean peptide and montmorillonite by X-ray diffraction and laser particle size analyzer were studied. What is more, the composite film was best when the amount of montmorillonite was 0.2g.