Evaluation of Physicochemical, Physical, Functional, and Optical Properties of Stored and Fresh Yam Tubers for Production of Quality Instant Pounded Yam Flour

Yam tubers are the most suitable food products closely integrated into the social, cultural, economic, and religious aspects of life. However, yams do not store well due to their perishable nature, which causes them to lose freshness and enter a dormant state rapidly. This study aims to use a single-cyclone flash dryer to produce high-quality instant pounded yam flour. As drying is a crucial method for maintaining food/agricultural produce to prevent post-harvest losses, selecting a suitable dryer is also key to producing quality flour. This study utilized a flash dryer due to its high efficiency and low energy consumption including high operating temperature (up to 200°C). The study uses white yam variety (Dioscorea rotundata) in two states: stored yams and fresh-harvested yams, with moisture contents of 59% and 72%, respectively. Findings from this study indicates that stored yam samples yield 29.12% more flour than fresh yam samples, indicating higher yields for food processors if stored yam is considered for IPYF production. Also, this study found that the moisture content of the samples significantly influences the flour's nutritional composition, as stored samples require lower drying temperatures than fresh yam samples. In addition, larger particle-size samples (4.5 μm) have lower moisture content post-grating, which affects the drying temperature and duration. This indicates that stored yam tubers are preferred due to their high quality and profitability. This study found that, despite the high drying temperature, the drying time is very short, helping preserve the nutritional and other essential properties of IPYF.