Interactions between exogenous free fatty acids and maize starches varying in amylose content at high heating temperatures

This study investigated the effects of adding 8.0% (w/w, dsb) free fatty acids (FFAs), including myristic acid (MA), palmitic acid (PA), stearic acid (SA), oleic acid (OA), and linoleic acid (LA), on the physicochemical properties of waxy (WMS), normal (NMS), and high-amylose maize (HMS) starches over 95–140 °C heating. After cooking the starch + FFA blends in Rapid Visco Analyser (RVA), the fully gelatinized NMS and HMS formed amylose-lipid complexes (ALC) with all the added FFAs. The developed ALC displayed melting temperatures of MA, PA, SA > OA > LA but discrepant trends in the melting enthalpy changes (ΔH) between the two starches. The FFAs noticeably elevated the final viscosity of NMS at 95 and 120 °C heating and that of HMS at 120 °C heating, but the increasing effect was not found at 140 °C heating. Most of the added FFAs significantly diminished the gel strength of NMS and HMS after 95–140 °C cooking. Among all the FFAs, SA – with the highest melting temperature (70.6 °C) – exhibited the poorest complexing ability with NMS and HMS and the least impact on their pasting and gelling properties; however, this FFA significantly improved the gelling ability of HMS after 120 and 140 °C cooking. The FFA addition generally exhibited negligible effect on the pasting and gelling properties of WMS. Our research revealed that, besides ALC formation, physical properties of the exogenous FFAs (e.g., melting temperature), the presence of endogenous ALC in starch, and the gelatinization temperature of starch significantly influenced the functional attributes of the different starch-FFA blends during 95–140 °C heating.