Casting Preparation And Properties Of Edible Films Based On Hydroxypropyl Distarch Phosphate

Basing on hydroxypropyl distarch phosphate, the film-making parameters of ediblehydroxypropyl distarch phosphate film, effects of melt-extrusion conditions on properties ofcomposite films, properties and antioxidant activities of edible hydroxypropyl distarchphosphate films incorporated with BHT and rosemary extract were studied. The main resultswere as follows:1. The film-making parameters of edible hydroxypropyl distarch phosphate film wereinvestigated. Based on single experiments，concentration of starch solution, glycerol content,pullulan content and heating temperature of solution were selected as independentvariables．The response of comprehensive score of film properties was used to make theresponse surface analyzer. The mathematic model were built by Box-Behnken Design. Theresult showed that the regression equation fit well, and the optimal film-making parameterswere as follows: concentration of starch solution of2.65g/100mL, glycerol content of28.81%（W/W starch）, pullulan content of12%（W/W starch） and heating temperature ofsolution of85℃. Under this condition, properties of films were tensile strength7.10MPa,water vapor permeability1.52×10^-12g·cm^-1·s^-1·Pa^-1, oil permeability0.51g·mm·m^-2·d^-1. Themathematic model could exactly forecast comprehensive score of film properties.2. Effects of extrusion temperature, screw speeds and water content on properties ofcomposite films were studied. The results indicated that, the tensile strength of films preparedwith melt-extrusion significantly decreased compared with that of films withoutmelt-extrusion. Under the conditions of extrusion temperature of140℃, screw speeds of30rpm and water content of25%, the elongation at break and water vapour permeability was95.31%and1.37×10^-12g·cm^-1·s^-1·Pa^-1, respectively. They were better than the potato starchfilm, corn starch film and sweet potato starch film. Heat resistance of films was higher than160℃. Therefore, these conditions could improve the defect of common films such as poorflexility, easy moisture absorption and poor heat resistance.3. Properties and antioxidant activities of edible hydroxypropyl distarch phosphate filmsincorporated with BHT and rosemary extract were investigated. The results showed thatincorporation of BHT and rosemary extract decreased tensile strength and elongation atbreak, and they were decreased from7.10MPa and38.81%to about4MPa and30% respectively. The films containing rosemary had higher tensile strength but lower elongationat break than the films containing BHT. The water vapor permeability reached its minimum1.25×10^-12and1.32×10^-12g·cm^-1·s^-1·Pa^-1respectively when the addition of both BHT androsemary extract at150mg/Kg. The color and transparency of the films were not significantaffected by addition of BHT. The additon of rosemary extract made the films deep yellow, anddecreased the transparency significantly. DPPH scavenging activities of films increasedmarkedly with the increase of BHT or rosemary extract concentration, and films containingrosemary extract had higher antioxidant activity. Films incorporated with antioxidants couldmore effectively delay the oxidation of oils and fats compared with the plastic film as thestorage time increased, and peroxide value of oil was under8meq/Kg. The FT-IR showedthat hydrogen bonding interaction of starch molecules was weakened after addingantioxidants. The SEM images showed that the surface of films containing antioxidants wasrelatively even and smooth.