Optimization of antioxidant rich vegetable powders from unconventional greens for preparation of instant soup mixes
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Date
2018
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Punjab Agricultural University, Ludhiana-
Abstract
The present study was conducted to assess the antioxidant potential of unconventional
vegetable greens namely turnip, radish, cauliflower and carrot and to optimize drying time
and temperature in hot air oven for the preparation of their corresponding vegetable leaf
powders with maximum antioxidant activity. The optimized drying time for turnip was 12
hours at 40°C while for radish, cauliflower and carrot leaves it was 14 hours at 40°C. At 50°C,
12 hours of drying period has been optimized for turnip, radish and carrot leaves at 50°C
while optimized time for cauliflower leaves was 10 hours. At 60°C, the optimized time for all
the vegetable leaves was 10 hours. Radish leaf powder had maximum antioxidant activity
(87.04%) at 40°C closely followed by carrot leaf powder (82.64%) at 50°C and turnip leaf
powder (82.34%) at 40°C. The least antioxidant activity among vegetable leaf powders was
observed in case of cauliflower leaves (38.84 to 51.38%) when dried for optimized time
periods at 40 to 60°C. The ascorbic acid content per 100 g of vegetable leaf powder was
maximum in turnip leaves (33.07 mg). Cauliflower leaves had highest chlorophyll (641.1
mg). Flavonoids were maximum in carrot leaves (1337 mg QE) Total phenols were the
highest in turnip leaves (784.9 mg GAE). The optimized vegetable leaf powders were
incorporated in a standardized recipe of instant soup mix at three levels i.e. 2.5, 3.75 and 5%.
In comparison to formulation where no vegetable leaf powder had been incorporated, the two
formulations which had been enriched with either turnip leaf powder and radish leaf powder
at 5% level had higher antioxidant activity i.e. 39.27 vs 41.58 and 44.80%, respectively. The
antioxidant activity of the soup formulations enriched with either turnip, radish or carrot leaf
powders did not reduce significantly after storage of two months. The antioxidant activity of
ten commercially available soup mixes varied between 18.64 to 34.45% with the mean value
of 25.21%. The three optimized soup mix formulations with or without the vegetable leaf
powders showed a significantly (p 0.01) higher antioxidant activity in comparison to the
commercially available soup mixes. Instant soup mixes enriched with either turnip or radish
leaf powder at 5% level had overall acceptability comparable to the formulation where no leaf
powder was incorporated. The instant soup mix supplemented with turnip leaf powder had
superiority over radish leaf powder in terms of consumer acceptability and preference for
purchase if available commercially.
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