Storage Stability of Pupuru Flour (A Cassava Product) at Room Temperature

Aims: The knowledge of water sorption Isotherm gives information about water activity of foods; to investigate chemical reactions during drying and storage. This study therefore, was to determine the sorption properties of pupuru flour during storage at ambient temperature.
Study Design: Research study.
Place and Duration of Study: The study was carried out in the Food Processing Laboratory of Food Science and Technology Department of Federal University of Technology, Akure, between April 2009 and December 2009.
Methodology: Adsorption characteristics of pupuru flour, a fermented cassava product, were determined at room temperature of 27°C using the static gravimetric procedure. Samples were equilibrated in desiccators containing tetraoxosulphate (VI) solution of known water activity (0.1-0.6). The data obtained were fitted to four moisture sorption models, namely Henderson, Chung Pfost, Oswin and Caurie for their predictive capabilities.
Results: The coefficients of determination varied from 0.881- 0.993. Both Henderson and Oswin models gave the most suitable models for describing the sorption data. The appropriate constants in the sorption equation were determined by regression analysis at temperature of 27°C. A comparison of the EMC curves showed that the toasted pupuru sample had lower equilibrium moisture contents than the smoked and oven dried samples at lower aw but higher EMC at higher aw.
Conclusion: It can also be concluded that the models are quite useful in assessing the storage stability of pupuru flour. The toasted pupuru flour has a higher sorption capacity and longer storage stability at higher aw of the tropics than the other two samples at atmospheric temperature of 29°C.