FFECTS OF HEAT TREATMENTS ON STORAGE PROTEINS AND FUNCTIONAL PROPERTIES OF GROUNDNUT MEAL
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Date
1991
Authors
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Mahatma Phule Krishi Vidyapeeth, Rahuri.
Abstract
The present investigations were undertaken to study
the effects of dry heat treatments to groundnut kernels on
the contents of soluble proteins, distribution of storage
proteins into different fractions and on the functional
properties of defatted groundnut flour. Freshly harvested
groundnut pods of the cv. UF 70-103 were obtained from the
Post-Graduate Institute Farm of the University, manually
shelled and the clean healthy kernels dried to about 8
per cent moisture at 4 0°C. The kernels (2 50 g each) were
separately heated at 100 to 180°C for 10 to 30 minutes in
hot air oven, cooled to room temperature, blanched
to remove skins, ground to 4 0 mesh and extracted in
Soxhelt apparatus with petroleum ether to remove fat. The defatted material was further ground to 100 mesh and used
for different analysis.
The heating of kernels at 100 -to 14 0°c for 30 min
significantly increased the content of soluble proteins.
A maximum increase in soluble protein content was found
in the kernels heated at 160°C for 10 min. Dry heat
treatments significantly affected protein distribution
pattern. The albumin + globulin fraction was found to
decrease from 58.51 per cent to 22.02 per cent with
corresponding increase in glutelin fraction from 25.46
to 60.6 per cent when the kernels were heated at 160 C
for 30 min.
The mild heat treatments (12 0 to 160°C for 10 to
2 0 min) generally improved the functional properties of
defatted groundnut flour. There was a significant
improvement in water and oil absorption capacities, as
well as foaming and gelation properties due to mild
heat treatments. The heat treatments however, resulted
in decrease in stability of emulsions formed by such
heated flours. More severe heat treatments (160 to 180 C
for more than 20 min) caused significant loss in soluble
proteins, albumin + globulin fraction and most of the
functional properties of defatted groundnut meal. The results therefore indicated that mild heat treatments
to groundnut kernels are beneficial to improve the
functional characteristics of groundnut flour. Further
investigations on varietal differences in functional
characteristics and factors reponsible for decrease in
gelation properties of heated groundnut flour, are
suggested.
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