FROM WASTE TO NEW BIOBASED EDIBLE COATINGS An ecological approach to improve the safety and shelf-life of foods

Abstract

The aim of this work is the utilization of sugar industry waste: sugar beet pulp and molasses, as a new approach for manufacture of raw chemicals that can be further converted into valuable products for food packaging industry. Dextransucrase is one of the main enzymes which catalyze the transfer of D-glucopyranosyl residues from sucrose to biopolymer dextran. New approach proposed the use of sugar beet pulp as a supporter for cells immobilization and molasses as the source of nutrient for production of dextransucrase by natural isolate from water kefir grain. Afterwards, the dextransucrase was purified and incubated in 5% sucrose/sodium acetate buffer solution (pH 5.4) at 30◦C for 48 h, in order to produce dextran. Dextran obtained by this procedure was used for preparation of edible biobased coating to prolong shelf-life of tomato. In order to improve mechanical properties of these coatings, poly(glycerol) was added. The dextran coatings were characterized by mechanical and thermal properties. Moreover, the tomato was coated with dextran film and evaluated periodically for various quality parameters. The tensile strength and elongation at break of dextran coatings was 1.62 MPa and 230%, respectively. Dextran coatings showed adequate thermal stability and could be safely used for applications up to 200oC. The coated-tomato reduced texture softening, weight loss and acid production compared with the uncoated tomato, which implied the prolongation of tomato shelf-life.