Effect of various pretreatment on the dehydration of onions and garlics
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Date
2005
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Journal ISSN
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Publisher
CCSHAU
Abstract
The present investigation was undertaken to study the effect of
various pretreatment on the dehydration of onion and garlic.
Onion and garlic were given different pretreatments viz., control
(no blanching), freeze shock and freeze shock + microwave heating. After
the pretreatments, the samples were dried in tray drier at 50, 60 and
700C. Samples were then analyzed for various parameters and drying
characteristics of onion and garlic. Moisture, dehydration ratio,
rehydration ratio, acidity, phenols, bulk density and organoleptic quality
were used for evaluating the product quality. Freeze shock + microwave
blanching was done for complete inactivation of peroxidase and catalase
activities. For onion (500g) microwave oven heating at 450 Watt (3 min.)
+ 80 Watt (7 min.) followed by freeze shock was observed while for garlic
it was (250g) microwave oven heating 450 Watt (5 min.) + 80 Watt (15
min.) followed by freeze shock.
In tray drier, the different temperature levels of 500C, 600C and
700C were used. There was no significant effect of drying temperature on
the organoletpic scores of onion. Freeze shock + microwave pretreatment
improved color, aroma and overall acceptability of dehydrated onion.
There was no significant effect of drying temperature on organoleptic
scores of garlic. Pretreatments had no effect on aroma and overall
acceptability but reduced color scores of dehydrated garlic. Chemically
and organoleptically freeze shock + microwave heating pretreated
samples were better than samples pretreated by freeze shock and control
samples.
Sample dried at 600C was found to be best among all the sample
in term of sensory quality of dehydrated onion and garlic.