Hydration behaviour of food grains and modelling their moisture pick up as per Peleg’s equation: Part I. Cereals

Cereals and millets generally hydrate at a
moderate rate and their hydration behaviour differs in native
and in processed state. The study was on the hydration
of paddy, milled rice, parboiled rice, wheat, millets and
equilibrium moisture content (EMC) on soaking at room
temperature. Paddy hydrated very slowly, hydration rate
was slow in brown rice but fast in milled rice and highest
in waxy rice. In most of the rice varieties, maximum
absorption occurred at the end of 30 min. In wheat hydration
rate was slow and its EMC was highest (43%). Maize
grits of big size hydrated slowly compared to small grits. In
coarse cereals EMC varied from 28 to 38%. Foxtail millet
hydration was slow whereas that of fi nger millet was fast.
The data were tested on the Peleg’s equation, which gave a
reasonable fi t to experimental data. Peleg’s constants k
1 and k2 were calculated for the above grains and their hydration
behaviour has been predicted. The model fi tted very well to
milled rice hydration data where the coeffi cient of variance
ranged from 0.9982 to 0.9995. With exception in some millet
the hydration data fi tted well with the Peleg’s equation.
Generalized equations have been formulated for prediction
of moisture content of cereals and millets.