2.1. Physicochemical properties of yam starch

Yam starch was extracted according to the methodology reported by Lozano et al. (2018) using a system of mucilage separation and starch extraction on a pilot scale, in which phase separation occurs due to the injection of air and the subsequent generation of mucilage-laden bubbles, thus allowing native starch to be obtained. For yam starch characterization, the water solubility index, water absorption index, and swelling power, were determined according to the methodology proposed by Wang et al. (2010). A starch suspension (4% w/v) was heated at 60 °C, 70 °C, and 80 °C for 30 min in a water bath with shaking after every 5 min. After cooling to room temperature (25 °C), the suspension was centrifuged run at 4500 rpm for 15 min. The supernatant liquid from each tube was transferred into Petri-dish to be oven-dried at 70 °C for 18 h. The dried residue was then cooled in desiccators and weighed for soluble starch. The water solubility index, WSI (Eq. (1)), water absorption index, WAI (Eq. (2)), and swelling power, SP (Eq. (3)), were calculated as follows:

where, Wg: weight of sediment (g), W: weight of dry solids in sample (g), and Ws: weight of dissolved solids in supernatant (g).