ORIGINAL PAPER Laboratory Process Development and Physicochemical Characterization of a Low Amylose and Hydrothermally Treated Ready-to-Eat Rice Product Requiring No Cooking Himjyoti Dutta & Charu Lata Mahanta Received: 19 July 2012 / Accepted: 17 December 2012 / Published online: 8 January 2013 # Springer Science+Business Media New York 2013 Abstract A low amylose and hydrothermally treated ready- to-eat rice product that requires no cooking was prepared in the laboratory. Hot soaking for 1–3 min with subsequent variable steaming at open and under pressures remarkably altered the kernel and flour properties. Increase in water absorption and lowering of cooking time with extent of steaming were prominent. Soaking of the product at 50 °C for 20 min gave texture values more similar to cooked samples. The viscosity parameters of hot soaking alone were in between those of hot soaking with open steaming and pressure steaming. Pressure steamed samples exhibited al- most constantly increasing slurry viscosity throughout the heating and cooling phases of the rapid viscosity analyzer profile. Steaming variably altered the native A-type X-ray diffraction pattern. Pressure steaming of samples with 3 min hot soaking caused complete loss of the A-type conforma- tion with feeble peaks for B- and V-type patterns. The open steamed samples showed peaks for all A-, B-, and V-type patterns. No endotherms for amylose-lipid complexes were however found in the differential scanning calorimetry of the pressure steamed samples. The raw rice flour was highly resistant to α-amylolysis. In open steamed samples, steam- ing severity decreased the hydrolysis rate indicating forma- tion of enzyme-resistant fractions, while pressure steamed samples showed higher digestibility with treatment severity. Keywords Rice . Texture . Cooking time . RVA . Crystallinity . Starch digestibility . Ready-to-eat Introduction The ease of cooking along with economy in fuel and time consumption have made the instant cooking and quick cooking starchy foods much popular in recent times. Instant rice is one, such example (Prasert and Suwannaporn 2009; Rewthong et al. 2011). Rice is principally parboiled or pre- cooked to bring about this peculiar characteristic. Paddy is generally not processed to give a ready-to-eat product that looks like whole parboiled rice. Parboiling is a unique hydrothermal technique involving soaking of paddy in water followed by steaming, drying, and milling. Hot soaking involving soaking in heated water is also followed by some processors where the steaming step could be omitted (Sareepuang et al. 2008). Parboiled rice possesses many improved properties like higher nutrition, higher head rice yield, lower insect infestation, improved shelling, etc. (Bhattacharya 1985, Lin et al. 2010). Parboiled rice, however, has a lower rate of water uptake during cooking requiring longer time to cook and hence more energy is consumed (Bhattacharya 1985). With increase in severity of parboiling, the time and energy consumption of the parboiled rice is further increased (Unnikrishnan and Bhattacharya 1987). Parboiled rice flour shows different properties from raw rice flour (Unnikrishnan and Bhattacharya 1987). Gelatinization and retrogradation are the basic phenomena involved behind all these changes. The extent of retrogradation is the principal factor for the end product quality (Yu et al. 2010). Due to formation of newer polymorphic structures during retrograda- tion, the native structure is never regained. These molecular changes are reflected in the changed properties of the rice kernel as well as the rice flour. Physical properties of kernel like color, appearance, kernel dimensions, density, cooking time, moisture absorption, etc. are very important for commer- cialization of the products (Shittu et al. 2009). The texture of Dr. Charu Lata Mahanta applied for an Indian patent. H. Dutta : C. L. Mahanta (*) Department of Food Engineering and Technology, School of Engineering, Tezpur University, Assam, India e-mail: charu@tezu.ernet.in Food Bioprocess Technol (2014) 7:212–223 DOI 10.1007/s11947-012-1037-9