Heat treatments could improve quality of vegetables?

SGROPPO , SONIA CECILIA; AVALOS LLANO, KARINA ROXANA; PEREYRA, MARÍA VICTORIA

Altering Material Properties.

Academy Publish

Lugar: Wyoming; Año: 2012;

This book will be published online as well as printed in hard-copy. Abstract: Heat shock treatment is a physical treatment that has a profound physiological effect on fresh vegetables increasing their shelf life. In our days, heat shock treatments joined with other technologies, are denominated as ?clean technologies?, because they do not affect people and environment. To apply these treatments, vegetables are immersed or dipped with hot water, vapour heat or exposed to hot air during minutes or hours and the temperatures used are between 40 and 65°C. Initially, hot water was applied to intact tissues of vegetables for fungal control and later for insect infestation. Vapor heat treatment was used for insect control and hot air for control of fungal diseases, disinfestations and quarantine treatments. Today, mild heat treatments are suggested to improve shelf life of minimally processed vegetables such us celery, lettuce, peppers, pears, peaches, kiwifruit and cantaloupe melon also. They would decrease mechanical or oxidative damage, and improve defense mechanisms in vegetables. As vegetable tissue response to stress after heat treatments, respiration rates of vegetables could be decreased, ripening delayed and chilling injury reduced. The microbial growth and insect infestations are limited. Besides, during storage, texture of some fruits and vegetables treated are better, losses of moisture are decreased and quality improved. Mild heat treatments have shown their effectiveness for improve color, decrease browning and increase desirable flavours or reduce other undesirable attributes. Many of these changes are due to modifications in gene expression, inhibition and synthesis of ?heat shock protein? (HSP) and are accompanied by a general inhibition of normal protein synthesis, as response to thermal stress. These responses of the tissues are dependent not only of time-temperature combinations of heat treatment applied, but also in the botanical structure of the vegetable, cultivars, maturity stage, climatic conditions, pre-treatments applied, etc. Heat treatments applied to some fruits and vegetables have demonstrated be useful in improvement the post-harvest life of the produce.