Development and application of polysaccharide-lipid edible coating to extend shelf-life of dry bakery products

This study investigated the effect of the deposition process used for film-forming dispersion (spreading and spraying), relative humidity gradient across the film (from 22-65% to 22-85%) and film thickness (15-90 mu m) on water vapor permeability (WVP), tensile strength (TS), percentage elongation at breaking (E) and structure of an emulsified edible film composed of corn starch, methylcellulose (MC) and soybean oil. The effectiveness of edible coating in controlling moisture transfer in moisture-sensitive products was evaluated by coating crackers, a low a(w)-type cereal food. Spread film gave better water vapor barrier and mechanical properties than sprayed film. High atomization pressure and thickness increased film WVP. Atomization pressure of 2 bar and film thickness of 30 mu m were identified as optimum for the application of edible coating to bakery products. Coated and uncoated (reference) crackers were stored at 65%, 75% and 85% relative humidity. Moisture uptake and resistance to water vapor transmission (r) were then calculated. Coated crackers had longer shelf-life and higher r than reference at all storage conditions. (c) 2005 Elsevier Ltd. All rights reserved.