Influence of low-temperature blanching on rheological behavior, pasting, and powder flow properties of creole yam (Dioscorea alata) flours

Abstract

Abstract This study is based on significant postharvest losses of creole yam (Dioscorea alata) and the limited information regarding the impact of thermal pretreatments on its rheological properties and it evaluated the effect of blanching at 40 °C, 50 °C, and 60 °C on the functionality of yam flour. Through steady-state and oscillatory rheological tests, shear-thinning analysis, and powder physical characterization, all samples exhibited non-Newtonian shear-thinning behavior, and the Herschel-Bulkley model adequately fitted the flow curves (R2 > 0.99). Blanching at 60 °C led to a reduction in yield stress (τ0 = 5.033 Pa) and an increase in the consistency index (K = 9.824 Pa·sn), with a flow behavior index of n = 0.431, likely associated with partial starch swelling or molecular rearrangement and the formation of a weak pseudo-gel-like network. The viscoelastic moduli (G′ > G″) confirmed the predominance of elastic behavior, supporting the potential use of these flours as thickening agents. The pasting profile showed that the sample blanched at 60 °C presented a peak viscosity of 88.60 Pa·s and a breakdown viscosity of 38.97 Pa·s, along with a notably low setback value (2.37 Pa·s), suggesting reduced retrogradation tendency. Bulk density decreased after blanching, whereas Carr index and Hausner ratio showed no significant differences among treatments (p > 0.05). All measurements were performed in triplicate and analyzed by one-way ANOVA followed by Tukey’s HSD test. These findings indicate that blanching at 60 °C improved selected functional attributes of creole yam flour, balancing flow initiation and structural development, which may be useful for food applications such as sauces and baby foods where texture stability is required.