This study investigated the effects of starch addition and type on the characteristics of extruded products of floury rice powder (FRP). Native starches from waxy, normal, and high-amylose corn, wheat, tapioca, and potatoes were used. Each starch replaced 30% of the dry weight of FRP. FRP and FRP-starch mixtures were extruded using a twin screw extruder at 19–20% moisture content, 18 Hz screw speed, and barrel temperature of 160℃, followed by drying at 80℃ for 3 h. The water absorption and water solubility indices of the FRP-starch mixtures were higher than those of starch alone, whereas swelling power exhibited the opposite trend. The gelatinization temperatures of the FRP-starch mixtures, except for the FRP-wheat starch mixture, shifted to higher temperatures than those of FRP, whereas their gelatinization enthalpies were lower. The pasting viscosities of the FRP-starch mixtures, except for the FRP-high-amylose cornstarch mixture, were higher than those of FRP. Regarding the extruded products, partial replacement of FRP with starch improved the expansion ratio and specific volume of the extrudates. The failure strength, measured using a 3-point bending test, was higher for the FRP-starch mixture (except for high-amylose corn and tapioca starches) than for FRP.

This study investigated the yellowing phenomenon of maesil (Prunus mume), changes in organic acid (OA), and cyanogenic glycoside (CN-Glc) contents during post-harvest ripening, and the potential use of ripened maesil as raw material for CN-Glc-reduced maesil chungs. Ripening conditions were as follows: 5℃ for Ripening I, 20–22℃ with 50–60% RH for Ripening II, 20–22℃ with 50–60% RH after ultrasonic washing of maesil for Ripening II-US, and 35℃ and 80–90% RH for Ripening III. Yellowing did not occur in maesil under Ripening I even after 7 days, but was observed after 7 days of Ripening II and Ripening II-US, and after 3 days under Ripening III. The OA content slightly decreased under all ripening conditions, while CN-Glc content significantly decreased, with ripening under all ripening conditions, with Ripening II and Ripening II-US being the most effective at reducing CN-Glc levels. In maesil chungs prepared from ripened maesil CN-Glc content was significantly lower than that of those made with untreated maesil. These results demonstrate that ripening under the conditions tested in this study significantly reduces CN-Glc content in maesil with minimal reduction in OA content, enabling the preparation of CN-Glc-reduced processed maesil products.