Optimization Of Film-forming Parameters Of Protein-starch-based Packaging Film And Study On The Effect Of Fresh-keeping Of Lettuce

Logistics of postharvest Fruits and vegetables decay seriously in our country,the amount of direct economic losses was enormous each year.From the point of transportation was the transfer of space,scientific and rational way of packing was more necessary to protect the product.Raw materials of production the traditional plastic packaging films were non-renewable,which polluting the environment,and were harmful in contacting with food directly.Edible packaging film has advantage of wide variety of sources,security edible and biodegradable non-polluting,was the focus researching of food packing.In this paper,with Zein,cross-linked starch and potato residue as the base material,complementing by other additives to manufacture protein-starch-based packaging films.With comprehensive performance of finished films as the indicator to optimize the packaging films.The best packaging film was used in storage test of lettuce and fresh-cut head lettuce,to investigate the best packaging film on the sensory and nutritional quality of lettuce and head lettuce.Observe the change in performance of the packaging film during storage.The results obtained are as follows:(1)The best film-forming component of protein-starch-based packaging film is:cross-linked starch 3.0%,Zein 1.0%,potato residue 1.0%,glycerin 2.0%,triethanolamine 1.0%,CMC 2.0%(quality volume).(2)Performance parameters of protein-starch-based packaging film is:tensile strength 10.50 MPa,elongation 36.5%,CO₂ penetration coefficient 3.24×10^-17 m²·g^-1·Pa^-1,WVP performance 422 g·m^-2·d^-1,light transmittance at 600nm was 46.1%,water-soluble 206 s.Characterization structure of packaging film texture uniform,smoothness and compactness were both well,film was yellow color,smooth,soft.(3)Protein-starch-based packaging film effectively slowed the weight loss,reducing of Vc content,reducing of chlorophyll content,the total number of colonies mounting of lettuce and fresh-cut head lettuce during storage at 4?,20?and 30?,have an good effect on extending the shelf life of lettuce and fresh-cut head lettuce.Lettuce and fresh-cut head lettuce stored 10d with this packaged at 4?,the weight loss,Vc content,Chlorophyll content and the total number of colonies are separately:8.35%and 13.41%?4.28 mg/100g and1.79 mg/100g?18.8 mg/g and 12.8mg/g?3172 CFU/g and 5909 CFU/g.(4)Stored for 30 days at 4?,the performance parameters of protein-starch-based packaging film are:tensile strength 6.22 MPa,elongation 11.2%,CO₂ penetration coefficient 4.64×10^-17 m²·g^-1·Pa^-1,WVP performance578 g·m^-2·d^-1.