ABSTRACT
Sorption isotherms are a significant source of information for establishing the stability of foodstuffs and their storage conditions. In agricultural and food technological processes, such as drying, handling, packaging, storage, and processes that require predicting food stability, shelf life, and prevention of deteriorative reactions, the characteristics of sorption isotherms play important roles. They are useful in developing or selecting, modeling, and controlling, as well as optimizing appropriate processes to enhance efficiency, especially in the storage of flours as well chips where knowledge of their hygroscopic nature is necessary. The aim of this study is to investigate the sorption isotherm of yam flour and cassava chips over a temperature range of 27°C, 35°C, and 45°C, as well as a water activity range (aw) of 0.07 - 0.84. Yam and cassava food samples were obtained from the Edaiken market in Benin and processed into flour and chips by washing, peeling, size reducing, and drying for 48 hours at 50°C for yam and 80°C for cassava in a hot air oven until they reached a moisture content of less than 14%. The dried yam was further processed into flour using a hammer mill, while the cassava was diced into chips. The physicochemical properties of the yam food samples, such as crude protein, crude fiber, moisture content, crude fat, nitrogen-free extract, and ash content, were determined. The equilibrium moisture content (EMC) of the yam flour and cassava chips was determined using the static gravimetric technique, which involves using a saturated salt solution to vary the micro-climate over selected temperatures and water activity (aw) of (0.07-0.84). To predict the equilibrium moisture content, plots of EMC against a w were used to generate isotherm curves, and the experimental sorption data were fitted to four sorption models: Guggenheim-Anderson-De Boer (GAB), Modified Henderson, HailwoodHorrobin, and Modified Halsey models using non-linear regression techniques.
