MOISTURE SORPTION ISOTHERM OF UNDERUTILIZED CULINARY BANANA FLOUR AND ITS ANTIOXIDANT STABILITY DURING STORAGE

The moisture sorption isotherm of vacuum dried culinary banana flour was studied using standard static-gravimetric technique at five different temperatures (25-45C). There was a gradual increase in equilibrium moisture content (EMC) between 0.1 and 0.65 water activities (a(w)), and EMC increased beyond 0.65 aw led to type II isotherm of sigmoidal characteristics. The effect of temperature on EMC was not significant at P > 0.05. Among the seven models fitted, Peleg model showed the highest coefficient of determination (R-2) with lower values of relative deviations (R-d<10%) and fulfilled the necessary criteria desired for the model and best fitted. The net isosteric heat of sorption (q(st)) determined from the equilibrium sorption data using Clausius-Clapeyron equation showed the decreasing trend of qst with increasing EMC. Additionally, the antioxidant and polyphenols stability of culinary banana flour monitored at 25C showed minor degradation up to 120 days without affecting its bioactive properties.