Fruit juices in polysaccharides edible films

In this study, jambolan and grape juices were used to produce polysaccharide-based edible films by the solvent-casting technique. The polysaccharides used were carboxymethyl cellulose, hydroxypropyl methyl cellulose, high-methoxyl pectin, low-methoxyl pectin, sodium alginate, and locust bean gum. The films exhibited good mechanical resistance and flexibility, with tensile strength (8 to 28 Mpa), elongation at break (6 to 36%), adhesion force (0.4 to 1.4 N), swelling index (1.0 to 2.3), and disintegration time (0.5 to 60 min) that varied as a function of the polysaccharide and the fruit juice used. The surface pH was, respectively, ~5.5 and ~4.6 for the films produced with grape and jambolan juices, regardless of the polysaccharide used. All films presented the typical color of the fruit juices, which was characterized by the L*, a* and b* parameters. The films produced with jambolan juice had the higher anthocyanin content (3.4 mg/g, d.b.) and antioxidant capacity (198 mMol Trolox equivalent/g, d.b.) when compared to those produced with grape juice (0.28 mg/g and 85 mMol Trolox equivalent/g, d.b.). The results are interesting for the food industry, specifically in edible or biodegradable films production, since alternative fruit juices can be used in food formulations and their natural compounds can replace synthetic additives. Key words: Alternatives fruits, Syzygium cumini L., Vitis vinifera L., antioxidant, anthocyanin, natural colorants.