Impact of Thermal and Chemical Pretreatments on Physicochemical, Rheological, and Functional Properties of Sweet Potato (Ipomea batatas Lam) Flour

The impact of thermal and chemical pretreatments on the physicochemical, rheological, and functional properties of sweet potato flour was investigated. The chemical pretreatment consisted in dipping peeled sweet potatoes in 1 % (w/v) calcium chloride (CaCl2), while the thermal pretreatment was achieved by blanching them in tap water at 90 A degrees C for 1 min. Composition in flour moisture, protein, fat, non-reducing sugars, and starch was determined using standard methods. Particle size, color, gelatinization, and rheological properties were analyzed. The water absorption index (WAI) and water solubility index (WSI), as well as the swelling capacity (SC) and sorption isotherms, were determined. The reducing sugar content of sweet potato flour was slightly higher in CaCl2-pretreated (SSPCaCl2) samples than that in blanched (SSPB) and control (SSP) samples. However, the lightness of the SSPB sample was lower than that of the SSPCaCl2 and SSP samples. SSPCaCl2 sample had the higher value of enthalpy of gelatinization and elasticity modulus G'. The SC was higher in blanched samples. A slight increase in the constant of water binding energy (C (BET)) was observed after the CaCl2 treatment and a marked increase for the blanched sample. Owing to the differences induced by blanching and CaCl2 pretreatments, CaCl2-pretreated flour samples are more suitable for bread-making processes and can also be used in food formulations.