Thin-layer drying kinetics of yam slices, physicochemical, and functional attributes of yam flour

This study aimed to investigate the effect of temperature (50-80 degrees C) on the drying behavior of yam slices and to evaluate the physicochemical and functional properties of yam flour. The results revealed that higher temperature enhanced the drying rate and moisture diffusivity (2.01 x 10(-10)-4.25 x 10(-10) m(2) s(-1)) and the drying process occurred entirely in the falling rate period. Twelve thin-layer drying models were employed to fit the drying data using statistical parameters; coefficient of determination (R-2), root mean square error, chi-square (chi(2)), sum of squares residual, and mean bias error. The results suggested that logarithmic for 50 degrees C (R-2 =0 .9990) and parabolic for 60-80 degrees C (R-2 =0 .9977-0.9991) were the best models that can adequately explain the drying behavior of yam slices. Different physicochemical and functional properties of yam flour were significantly affected by the drying temperatures. However, the developed yam flour exhibited a satisfactory range of nutritional contents, such as protein (4.79-5.97%), fat (0.59-0.74%), ash (5.57-6.60%), fiber (0.83-1.96%), starch (65.59-73.93%), carbohydrate (85.69-87.53%), and total phenolics (10.68-11.88 mg Gallic Acid Equivalent/100 g (GAE/100 g). Therefore, the drying kinetic results and the physicochemical quality of developed yam flour could be useful for its industrial production. Practical Applications Yam is one of the leading root crops in the world and used as staple food in many countries. Postharvest storage and transport of the raw yam are one of the main problems in developing countries. The objective of this study was to investigate the effect of drying temperature on the thin-layer drying kinetics of yam slices and to evaluate a suitable drying model for describing the drying process together with the food compositions, total phenolics, and other functional and color characteristics. This study revealed a useful outcome that could convince the food producers for industrial production and consumers to consider the yam flour as a suitable alternative to rice, wheat, or corn flour for the formulation of high-quality health food products, such as bakery, confectionery, snack, noodle, soup, and other products.