Use of potato by-products and gallic acid for development of bioactive film packaging by subcritical water technology

Interest in the development of bioactive packaging has been rising due to environmental concerns, regulations and the need to extend food shelf life. The objective of this study was to produce bioactive films from potato by-products using subcritical water (SCW) technology with(out) gallic acid added. Different potato peel/cull ratios and glycerol/cull starch ratios were first evaluated. Then, different amounts of gallic acid were added to improve film antioxidant activity. All bioactive films produced were characterized by physical, chemical and functional properties. Films added with potato peel had less tensile strength (0.9-7.8 MPa) with increasing plasticizer concentration (0.5-2.0 g glycerol/g starch). Water activity of all films varied from 0.0671 to 0.0893, which are ideal to avoid microorganism growth. The film antioxidant activity reached up to 1899.1 mg Trolox equivalent/g starch at 0.3 g gallic acid/g starch. Therefore, SCW is a powerful technology to produce bioactive films made of potato by-products.