Cooking quality, textural characteristics and sensory evaluation of heat‐moisture treated unpolished red rice under different cooking conditions

Summary The unpolished red rice (URR) previously has been heat‐moisture treated to significantly improve resistant starch content. Continuously, this study aimed to investigate cooking quality, textural characteristics, and sensory evaluation of the URR, and heat‐moisture‐treated URR (HMT‐URR), cooked with water or 0.5 m acetic acid solution (AAS) at 80 or 100 °C for different cooking time ranging from 30 to 70 min. The degree of gelatinisation (DG), water absorption index (WAI) and cooking loss (CL) of the cooked URR and HMT‐URR significantly increased with the increased cooking temperature or time. The results of DG also showed that whole URR and HMT‐URR were well cooked with water at 80 °C for 70 min or with the AAS at 80 °C for 60 min or at 100 °C for 40 min for both. Although the cooked HMT‐URR was much harder than the cooked URR, the hardness of the HMT‐URR was significantly reduced when cooking with the AAS. The morphological structure also indicated that the URR and HMT‐URR cooked with the AAS were more well gelatinised. As a result, the HMT‐URR cooked with 0.5 m acetic acid solution had high scores in terms of all organoleptic attributes even though their odour and flavour were less preferable.