The enzymes amylase, protease, phosphatase and beta-glucosidase in rou
gh rice (paddy) were activated during the soaking step of parboiling.
The extent of activation of these enzymes varied with the soaking dura
tion and the parboiling methods adopted. Highest activities were obser
ved in the cold soaking method followed by the double steaming and hou
sehold methods. beta-Glucosidase activity was eliminated in the preste
aming stage of the double steaming process. Hot soaking inactivated al
l these enzymes. The steam in the parboiling process inactivated the e
nzymes partly while the pressure parboiling process inactivated them t
otally. Studies with purified enzymes also revealed the activation of
enzymes during soaking. Enzyme activity contributes to the loss of sol
ids during soaking and also to the characteristic odor of parboiled ri
ce.