One way to alleviate the adverse effect of hot air
drying is to pretreat a product, either physically or chemically,
prior to drying (Gornicki and Kaleta, 2007). The main
purpose of pretreatment is generally to inactivate enzymes
such as polyphenoloxidase, peroxidase and phenolase and
to inhibit some undesirable chemical reactions, which cause
many adverse changes of a product. Many pretreatment techniques
have been used in food industry, including blanching
and use of weak acids