engleski

Physico-chemical properties of pectin based edible coatings

For the past ten years the application of edible materials as a thin layer coatings, placed directly on a food or formed into a film has been increased due to its biodegradable and environmental friendliness activities. Such films can mechanically protect foods, prevents contamination from microorganisms and quality loss (moisture, gases, flavours, etc.). In addition, edible films and coatings can be used as a matrix for incorporation of different natural or chemical antimicrobial agents, antioxidants, enzymes or functional ingredients. Therefore, among various edible polymers (polysaccharide, protein and lipid), this work offers application of commercially available apple pectin for formation of pectin-based bio-coatings. The films were prepared using different mass fractions of pectin (0.5, 1.0 and 1.5 %), glycerol (50 and 70 %) and calcium chloride (1 and 2 %), dissolved in distilled water or 10 % (v/v) ethanol. Thus, 24 different pectin-based films were examined, in particular, the colour, water absorption index (WAI), water solubility index (WSI), as well as mechanical hardness, cohesiveness, elasticity and adhesiveness. Results indicated that all biofilms are suitable coating materials, considering that the samples with the highest pectin mass fractions (1.5 %) exhibited greater resistance to strain. Except pectin amounts, mechanical strength of biofilms is also influenced by amounts of plasticiser and cross-linker added to the pectin-base solutions. Thus, better mechanical resistance showed biofilms prepared with 50 % glycerol and 2 % calcium chloride. Due to the fact that all obtained biofilms possessed excellent textural properties, further investigations will be focused on formation of coatings composed by pectin extracted from tomato peel waste using the same amounts of polymer, plasticiser and cross-linker involved in this study.

biofilm ; colour ; edible coatings ; mechanical properties ; pectin ; water absorption index ; water solubility index

nije evidentirano