A Pressure Cook–Cool Process with Coconut Oil and Thai Herbs Enhances Resistant Starch, Antioxidant Activity, and Prebiotic Potential in Khao Dawk Mali 105 (KDML 105)

Khao Dawk Mali 105 (KDML 105) is a widely consumed Thai staple, but conventional cooking yields rapidly digestible starch with limited functional health benefits. This study aimed to formulate pressure-cooked KDML 105 rice as a functional food using extra–virgin coconut oil, citric acid, and Thai herbs (butterfly pea flower or pandan leaf juice). Rice was pressure-cooked, cooled at room temperature, stored at 4 °C for 24 h, and frozen at −20 °C to promote resistant starch (RS) formation. RS content increased from 0.65 g 100 g−1 DW in control rice to 1.39 g 100 g−1 DW with coconut oil, and to 2.08 and 1.80 g 100 g−1 DW when citric acid plus pandan or butterfly pea juice were added, respectively. Coconut oil-treated samples showed higher antioxidant activity in DPPH and FRAP assays, while formulations with butterfly pea or pandan juices additionally reduced ABTS•+ radicals. Prebiotic potential was evaluated in vitro using Levilactobacillus brevis, Lactobacillus bulgaricus, and Streptococcus thermophilus grown in MRS medium with rice extracts. All formulations enhanced probiotic growth versus control, indicating that this pressure cook–cool process can produce a ready-to-eat functional rice with improved RS, antioxidant capacity, and probiotic support.