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Applications of edible coatings and films in foods 
Recent studies have indicated how edible films and coatings can prolong the shelf-life and improve the quality of different products. Large, chilled fruit pies (of 300- 500g) have a chilled shelf-life of about a week.The limit is because of water migration from the relatively moist pie filling (water activity above 0.9) to the relatively dry pastry, causing the pastry to go soggy. Two different techniques were found to be effective in delaying this migration.The application of lipid-based edible films between the two components was effective, when applied to previously-baked pastry. As an alternative, carbohydratebased films could be used, but these were most effective when applied to the pastry before filling and baking. In similar work on ambient-stable individual pies, it was found that, over the extended shelf-life of these products, the rate of moisture loss from the pastry exceeded the rate of moisture migration from the filling, so that edible films were of limited use. Fresh fruit can also benefit from the application of an edible coating. In work to determine the effectiveness of the commercial product NatureSeal, which is a blend of vitamins and minerals designed to inhibit respiration and oxidation (especially browning reactions) of fresh cut fruit, it was found that the application of the coating did improve the eating quality of pears, increasing their shelf-life. Degradation was reduced and the pears stayed fresher for longer. Yeast, mould and total viable microbial counts also tended to be lower in the treated pears. Contact: Sarah Chapman |