Effects of edible film coatings on shelf-life of mustafakemalpasa sweet, a cheese based dessert

It was aimed to investigate the shelf-life of single baked (one stage heating at 280-300 °C) mustafakemalpasa (MKP) cheese sweets coated with edible films such as κ-carrageenan, chitosan, corn zein and whey protein concentrate (WPC). The sweets prepared were coated, packed in polystyrene bags and stored at room temperature (20 ± 1 °C). The shelf-life of sweet samples was determined by microbiological analyses, aw, titratable acidity, pH and sensory analysis. The microorganisms exhibited growth dependent upon the water activity levels during storage. The most significant growth was seen in moulds and yeasts. The minimum aw values for the growth of mould and yeasts were 0.85. Coating with chitosan and κ-carrageenan showed no significant effect on shelf-life of MKP sweets. The shelf-life of these samples was limited by 3 days same as control (non-coated) and deterioration occurred when the aw value reached 0.90. The coatings with WPC and corn zein prolonged the shelf-life of sweets from 3 to 10 days.

Immobilization of lysozyme on polyvinylalcohol films for active packaging applications

A new technique for the immobilization of lysozyme onto the surface of polyvinylalcohol films is presented. The active compound was sprayed along with a suitable bonding agent onto the surface of the cross-linked polymeric matrix. Active compound release tests determined the amount of lysozyme immobilized on the film surface. With the use of Micrococcus lysodeikticus, the antimicrobial activity of the films was determined and the results correlated with the amount of immobilized lysozyme. This new technique was effective for immobilizing the enzyme, and the developed films were active against the test microorganism. Results were compared with those obtained with a different immobilizing technique, in which the active compound was bound into the bulk of the polymeric film. As expected, the surface-immobilized lysozyme films have a higher antimicrobial activity than bulk-bound films.