Combined Industrial Processes with Irradiation to Assure Innocuity and Preservation of Fruits and Vegetables

Irradiation in combination with mild heat treatment, modified atmosphere packaging (MAP) and/or edible coating could be beneficial to maintain the innocuity and prolong the shelf life of fruits and vegetables. We have demonstrated the usefulness of mild heat treatment prior to low dose irradiation in extending the shelf-life of fresh mangoes and citrus fruits without affecting their normal quality. Besides the possibility of microbial reduction, irradiation treatment can extend the shelf-life of fruits and vegetables by regulating the phenylalanine ammonia lyase (PAL) and/or polyphenol oxidases (PPO) activity resulting in the reduction of tissue browning. Lowering the dose rate of irradiation following storage under MAP conditions was effective to protect the colour by the protection of the cellular membrane of mushrooms and to assure a shelf life improvement. MAP is also effective to retard the growth of bacteria and prevent the whitening development during storage of irradiated minimally processed vegetables. Edible coating is a new technology that has been introduced in food processing to increase the shelf life of foods. Studies developed in our laboratories demonstrated that gamma irradiation improved edible coating development via the production of cross links in the coating. The alternative combination of an edible coating and irradiation treatment was used to maintain the quality of fresh strawberries and mini peeled carrots. Our results showed that combined treatments with edible coating were effective in reducing water losses, mould growth and preventing the whitening of these products. Coating with edible film could also be efficient to delay browning by acting as oxygen barriers or scavengers. Examples of the applications of these combined treatments to fruits and vegetables will be presented.