Vasudeva Singh

Effect of processing paddy on digestibility of rice starch by in vitro studies.

Paddy (Oryza sativa L) (variety ‘IR — 64’), was parboiled, puffed by sand roasting and flaked by edge runner and roller flaker and variations in physical and physicochemical properties were studied. Moisture contents were lower (5.8–10.8%) in processed rice products compared to raw materials (11.8%). Ratio of rice to sand in the case of puffed rice preparation was optimized. The equilibrium moisture content was 27.4% in raw rice while it was much higher (38.9–81.0%) in processed rice. Sedimentation volume was lowest (6.2 ml) in raw rice and highest (18.8 ml) in popped rice. Starch content was 84.8 and 76.5–83% in raw and processed rice, respectively. In vitro starch digestibility was highest in roller flaker flakes and lowest in raw milled rice. Among the ready to eat products, popped rice showed least starch digestibility (∼30%).

A comparative study on starch digestibility, glycemic index and resistant starch of pigmented (‘Njavara’ and ‘Jyothi’) and a non-pigmented (‘IR 64’) rice varieties

In vitro starch digestibility and glycemic indices of three rice varieties- ‘Njavara’, ‘Jyothi’ (pigmented rice verities) and ‘IR 64’ (non-pigmented rice) with similar amylose content were studied. Starch digestibility studies showed differences in glycemic response in three types of rice. The rate of starch hydrolysis was maximum (67.3%) in ‘Njavara’ rice compared to other two rice varieties. ‘Njavara’ exhibited the lowest kinetic constant (k) indicating inherent resistance to enzymatic hydrolysis. The glycemic load (GL) and glycemic index (GI) of ‘Njavara’ were similar to ‘Jyothi’ and ‘IR 64’. Resistant starch content was high in pigmented rice varieties compared to ‘IR 64’. The resistant starch content of dehusked and cooked rice increased with the storage time at refrigeration temperature (4°C). ‘Njavara’ is an easily digestible rice and can be used for baby and geriatric foods.

Production of Okara and Soy Protein Concentrates Using Membrane Technology

Microfiltration (MF) membranes with pore sizes of 200 and 450 nm and ultrafiltration (UF) membranes with molecular weight cut off of 50, 100, and 500 kDa were assessed for their ability to eliminate nonprotein substances from okara protein extract in a laboratory cross-flow membrane system. Both MF and UF improved the protein content of okara extract to a similar extent from approximately 68% to approximately 81% owing to the presence of protein in the feed leading to the formation of dynamic layer controlling the performance rather than the actual pore size of membranes. Although normalized flux in MF-450 (117 LMH/MPa) was close to UF-500 (118 LMH/MPa), the latter was selected based on higher average flux (47 LMH) offering the advantage of reduced processing time. Membrane processing of soy extract improved the protein content from 62% to 85% much closer to the target value. However, the final protein content in okara (approximately 80%) did not reach the target value (90%) owing to the greater presence of soluble fibers that were retained by the membrane. Solubility curve of membrane okara protein concentrate (MOPC) showed lower solubility than soy protein concentrate and a commercial isolate in the entire pH range. However, water absorption and fat-binding capacities of MOPC were either superior or comparable while emulsifying properties were in accordance with its solubility. The results of this study showed that okara protein concentrate (80%) could be produced using membrane technology without loss of any true proteins, thus offering value addition to okara, hitherto underutilized. Practical Application: Okara, a byproduct obtained during processing soybean for soymilk, is either underutilized or unutilized in spite of the fact that its protein quality is as good as that of soy milk and tofu. Membrane-processed protein products have been shown to possess superior functional properties compared to conventionally produced protein products. However, the potential of membrane technology has not been exploited for the recovery of okara protein. Our study showed that protein content of okara extract could be improved from approximately 68% to approximately 81% without losing any true proteins in the process.

Characterization of Antioxidant Compounds and Antioxidant Activity of Indian Rice Varieties

The present work is aimed at characterisation of phenolic acids and rice bran oil (RBO) of Njavara, a medicinal red rice variety and other rice varieties. The antioxidant activities of the rice polyphenols were also studied by radical scavenging assay, reducing power and microsomal lipid peroxidation. Pigmented rice varieties (Njavara and Jyothi) had high antioxidant activities than non-pigmented variety (IR 64). Acetone extracts showed higher phenol content and antioxidant potency compared to methanol and ethanol extracts. Njavara showed higher reducing capability and higher soluble (15%–46%) and insoluble phenolic acids (51%–75%) compared to Jyothi and IR 64. An array of phenolic acids were identified, the major being ferulic and p-coumaric acid. The ferulic acid concentration of Njavara in soluble and insoluble form was 33%-66% and 51%–75% higher, respectively, than non-medicinal rice. Njavara RBO was a better source of tocopherols. However, oryzanol composition of Njavara was similar to Jyothi and IR 64.

Nutrients, Nutraceuticals and Bioactive Properties of Multi-Whole Grain Mix for Drink and Porridge

Whole grains are reported to be rich in nutrients, nutraceuticals and have number of health beneficial effects. A convenient multi-whole grain mix for the preparation of a drink or porridge was formulated by using cereals, millets, pulses and nuts. Particle size was mostly of 180-250 microns (52%). Amylograph characteristics like GT, PV, HPV, CPV were 82 ° C, 285BU, 310BU, and 605BU, respectively were ideal for drink. The mix was found to be rich in carbohydrate, protein, fibre and calorie. The 100g of the mix had nutraceuticals like carotenoids (290µg), I³-tocopherol (4.6mg), I±-tocopherol (1.5mg), and polyphenols-soluble, bound and total (94,132 and 226mg GA Eq.). Bioactive properties like vitamin E activity, free radical scavenging activity, total antioxidant activity and starch digestibility were 2.6i.u., 153mg catechin.Eq./100g, 17mg Tocopherol equivalent and 61.8%. Mix was sensorily acceptable in the form of drink and porridge and can be used as an ideal nutritious food for all age group.