Edible coatings for fruits and vegetables

Abstract

Purpose of the review: This review examines the effects of edible films and coatings on overall quality of whole and fresh-cut fruits and vegetables, providing an understanding of their main functions and beneficial effects of each type of coating. Findings: Technological advances have resulted in new types of edible coatings where different ingredients and new formulations are used. Properties of edible coatings have been improved and now are more specific barriers to moisture, fat, O2, flavor and aroma, and protective coatings of additives such as antioxidants, antimicrobials and nutraceuticals. Coatings can be formed from a wide range of materials such as polysaccharides, proteins and lipids and their application to different fruits and beneficial effects are well discussed. Limitations/implications: The new trends on consumption of natural fresh-cut produce and the development of more attractive package systems is an opportunity to increase the use of edible coatings to maintain the overall quality of these products. However, if there is an inadequate selection of the materials and methods of application, edible coatings could cause anaerobic respiration or desiccation of the product affecting its overall quality. Therefore, the proper selection of materials that will provide the physical characteristics of the edible coating for a specific produce, is critical. One of the most common practical problems is that the coating material may not be friendly with the food surface, not covering the produce homogenously. The inadequate storage conditions (temperature, humidity relative, among others) could affect the physical properties of the coating, and as consequence the edible coating will not be able to accomplish its objectives and provide the benefits to the product for which initially was created. Choosing a proper coating is thus complex because it depends on the specific respiration and transpiration rate of the commodity and the outside environmental conditions. A clear understanding of how an edible coating will work on different produces is not easy, because the response of different commodities will differ significantly with the cultivar and storage conditions. Directions for future research: Recent studies have been focus on the ability of edible coating as carriers and are being more used as delivery systems of antioxidant and antimicrobial compounds. The use of natural compounds such as essential oils and volatiles has been combined with some edible coatings in order to have an additive effect and diminish the major deteriorative processes of fruits and vegetables such as browning and fungal decay. The addition of additives to increase the nutritional value of fruits is a novel practice that has been more familiar and accepted by consumers that demand for more functional foods. More studies are needed in order to evaluate the mechanisms involved in the delivery of natural compounds carried in the edible coatings and how temperature, humidity and time, affect the release of these compounds to the environmental and if they reach adequately the produce and have its function for which was created.