Chemical Composition, Pasting Profile and Physicochemical Properties of Rice Varieties Cultivated in South Kalimantan

Rice quality is largely determined by its chemical composition, pasting properties, and physicochemical characteristics during cooking. Amylose content plays a key role in defining cooking quality, texture, and consumer preference. This study aimed to evaluate the chemical composition, pasting properties, and physicochemical characteristics of five rice varieties (Ciherang, Gunung Wangi, Siam Mayang, Siam Unus, and Mutiara) cultivated in South Kalimantan, Indonesia. Chemical composition was analyzed for starch, amylose, protein, and lipid contents. Pasting properties were determined using a Rapid Visco Analyzer (RVA), while physicochemical properties included volume expansion, water uptake, and total soluble solids. Significant differences among varieties were observed. Amylose content ranged from 20.75% to 33.56%, with Ciherang and Gunung Wangi classified as medium amylose, and Siam Mayang, Siam Unus, and Mutiara as high amylose. High-amylose varieties exhibited higher pasting temperature (85.60–89.30 °C), lower peak viscosity and breakdown, and greater setback values. Siam Mayang showed the highest water uptake (300.18%) and the lowest soluble solids (0.22%), while Ciherang exhibited the highest soluble solids (1.25%). Protein content ranged from 7.06–8.48% and was associated with differences in texture and cooking time. Amylose content is the main factor influencing pasting and physicochemical properties of rice, ultimately determining cooked rice quality. High-amylose varieties produce firmer, less sticky rice, while medium-amylose varieties yield softer, stickier rice. This study highlights that amylose content and starch structure (amylose–amylopectin ratio) are the dominant factors shaping the pasting behavior and physicochemical characteristics of rice.