"Heat sensitive foods and products that possess excellent quality in terms of taste, aroma, texture, and appearance, such as herbs, spices, seafood, etc., pose a major challenge to food driers. Products such as garlic, ginger, spring onions and shrimps are cellular tissues containing gas-filled pores that tend to collapse when subjected to dehydration. This collapse is more noticeable with prolonged exposure to elevated drying temperatures, such as those used in convective drying. For this reason, hot air drying results in substantial degradation in quality attributes such as colour, nutrients and flavour, sever shrinkage also reduces bulk density and dehydration capacity. Also, chemical changes causing loss of flavour and nutrients occur during convective drying so the properties of dehydrated products are poor. A number of drying techniques have been developed over the years, among them atmospheric forced-air dehydration, a very common method. The major disadvantage of the hot air convective drying of food is the low energy efficiency and lengthy drying time during the falling rate period.
MILD-DRY will build on the positive results of laboratory trails using microwave-assisted vacuum drying (MAVD) for the successful dehydration of selected foods, whereby the drying time for carrots for example was reduced to 2 h compared with 4.5-8.5 h in convectional hot air drying. Moreover, dried carrots showed higher rehydration potential, higher beta-carotene and vitamin C contents, lower density, and softer texture than those prepared by air drying. Further research effort will be performed in order to optimise the approach through the intermittent as opposed to continuous application of MW in order to achieve higher energy savings and product quality enhancement. To bridge the gap between laboratory research and industrial application, a prototype system will be developed for its validation in commercial food drying facilities."
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Funding SchemeBSG-SME - Research for SMEs
SR5 3TX Sunderland
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