Improved functional properties of Dioscorea alata var. Purpurea flour after heat moisture treatment: Thermal, pasting, and granule stability

Abstract

Heat moisture treatment (HMT) of flour is a critical process in the food industry that affects the functionality and quality of flour-based products. The study aims to elucidate the complex interactions between heat, moisture, and flour components, including proteins, starches, and lipids, to gain insights into the mechanisms that influence the functional properties of treated flour. By enhancing this understanding, it will be possible to optimize the HMT process parameters and manipulate the flour characteristics to meet the specific requirements of different food applications. Purple yam flour was successfully modified by heat–moisture-treatment (HMT) with an autoclave (AHMT) and oven (OHMT) as thermal sources. After HMT treatment, purple yam flour was analyzed for oil (OAC) and water (WAC) absorption capacity and several related characterizations such as thermal character using Differential Scanning Calorimetry (DSC), surface structural using Scanning Electron Microscopy (SEM), and paste properties using Rapid Visco Analyzer (RVA). The findings have shown that O-HMT and A-HMT flours had an increasement in all the OAC, WAC, and thermal characteristics (To, Tp, Tc, ΔT) as compared to the original flour with an increment in gelatinization temperature by 1–4 °C. There were no alterations in granule morphology with O-HMT and A-HMT treatments and they demonstrated only an accumulation at 30% moisture content treatment. Pasting characteristics presented an increasement in dough processing temperatures causing both modification treatments within the range of 3–15 °C. Meanwhile, peak, trough, breakdown, back, and final viscosities were decreased due to O-HMT and A-HMT treatments. The present study demonstrates that both treatments enhanced the performance properties of purple yam flour and that could be considered safe methods for modifying the functional flours derived from purple yam.