Abstract—Sweet sorghum is rich in sugar and high in biomass which makes it suitable as substrate for bioethanol production. However, the problem with this crop is the short storage duration of the stalk due to high sugar content at high moisture content upon harvest. The study aimed to determine moisture sorption isotherm model for sorghum stalks and investigate the effect of drying on fresh sweet sorghum stalks. According to GAB model, the moisture content at which the microbial activity for the dried stalk becomes limited was computed as 0.24 gram moisture per gram dry mass or lower, considering the water activity at 0.70 where bacterial and fungal growth becomes limited. Moisture content of samples also exhibited changes during storage for both fresh and dried samples. The changes were brought by chemical and microbial activities occurring in the packed samples, respiration in particular, with water as the by-product. Stalks with lower water activity were proliferated by molds and yeasts while stalks with higher water activity were more suitable for bacterial growth.
 

Index Terms—sweet sorghum, drying, water activity, bioethanol, sugar content

Cite:  Melanie Blanca-Ocreto, Arnold R. Elepaño, Kevin F. Yaptenco, Ernesto P. Lozada, and Ernesto V. Carpio, "Determination of Moisture Sorption Isotherm Model for Dried and Fresh Sweet Sorghum [Sorghum bicolor (L.) Moench] Stalks," Journal of Advanced Agricultural Technologies, Vol. 4, No. 4, pp. 308-312, September 2017. Doi: 10.18178/joaat.4.4.308-312