WATER ADSORPTION PROPERTIES of COATED and NONCOATED POPCORNS

The addition of sugar for coating changed the sorption behavior of popcorn and made it more hygroscopic above a_w value of 0.65. the isotherms for noncoated popcorn exhibited a slight sigmoid shape and for coated showed the shape characteristics of high sugar containing foods. the crossing of both popcorn samples was observed at 0.65 a_w. the BET, the Smith and the GAB models were found to fit the adsorption data of noncoated popcorn; however, the BET and the Iglesias & Chirife models gave a good fit to the data of coated popcorn. the monolayer moisture content values estimated for both samples were considered to be correct values because of low standard error of estimates and their consistency with the literature values. the isosteric heat of noncoated popcorn was higher than the coated popcorn in the entire moisture content range considered for computation.