STUDI ISOTERM SORPSI CABE MERAH [ Capsicum annuum L.] DENGAN MODEL BET [ Brauneur - Emmet - Teller ] DAN GAB [ Guggenheim - Andersson - DeBoer ]

Abstract

The shelf life and s afety of perishable products is related to the water activity [a w ], rather than the water content, that deter mines the microbial safety and the physical texture of processed foods. Water sorption may be either adsorption or desorption. Sorption isotherms show the amount of water adsorbed as a function of steady state relative vapor pressure at a constant temperat ure. The relative vapor pressure of water in a food and in the surrounding atmosphere are also equal and therefore it may be stated that water activity is obtained from relative humidity of air. The aim of this research was to study the sorption isotherms of capsicum annuum L by BET and GAB models. The results showed that the water adsorpstion isoterms of capsicum annuum L by BET and GAB models followed the shape of the sigmoid. The linerized for fitting the BET model and in the form of second - order polyno mial for fitting the GAB model. Both of the sorption isotherms models g a ve well predition on a w at 0.3 - 0.7. The shelf life and safety condition for capsicum annuum L storage is 70% to 80% relative humidity. The BET and GAB models are applicable to predict water sorption of capsicum annuum L and its can also be used to calculate the monolayer value.
Key words : capsicum annuum L, sorption isotherms, BET, GAB