Effect of parboiling methods on the physicochemical characteristics and glycemic index of rice varieties
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ORIGINAL PAPER
Effect of parboiling methods on the physicochemical characteristics and glycemic index of rice varieties S. K. Sivakamasundari1 · J. A. Moses1 · C. Anandharamakrishnan1 Received: 17 February 2020 / Accepted: 3 July 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract The effect of open steaming (HS) and pressure (PP) parboiling on the physicochemical characteristics and glycemic index (GI) of five different Indian rice varieties with varying amylose contents was investigated. Results showed that the severity of processing had a significant effect on the physicochemical properties of rice. PP resulted in reduced whiteness (18.83 ± 0.66 to 26.03 ± 1.27%), increased transparency (1.64 ± 0.05 to 2.05 ± 0.08%), hardness (6.66 ± 0.63 to 7.82 ± 1.19 kg) and equilibrium moisture content (117.59 ± 11.37 to 183.69 ± 39.46%db). PP rice also showed higher cooking time (40.28 ± 0.35 to 59.31 ± 0.69 min), water absorption ratio (4.52 ± 0.06 to 5.23 ± 0.04), and sedimentation volume than HS and non-parboiled counterparts. An increase in parboiling temperature significantly affected the pasting profiles of rice flour. Among the treated samples, the degree of gelatinization was higher for PP rice (70.80 ± 6.83 – 85.24 ± 1.48%). Alkali spreading value explained the lower gelatinization temperature for parboiled rice as compared with the non-parboiled counterpart. Higher amylose content of rice was associated with lower GI values and parboiled rice had a significantly lesser GI. The findings of this study provide insights on rice parboiling methods, particularly for the diabetic population. Keywords Rice · Parboiling · Gelatinization temperature · Pasting properties · Glycemic index
Introduction Rice (Oryza sativa L.) is an important staple crop in most Asian countries and is a good source of dietary fiber, niacin, riboflavin, and thiamine, offering broad prospects for value addition. Starch is the major component of rice and is composed of amylose and amylopectin. Rice is generally regarded as a higher glycemic index (GI) food associated with potential risks to diabetes, obesity, and cardiovascular disorders. Varietal differences can produce rice with varying levels of amylose, in turn, with varying GI values [1]. Further, the processing of rice could alter the GI and such processing methods include soaking, parboiling, de-husking, polishing, ageing, germination, puffing, flaking, cooking, and cooling [2].
* C. Anandharamakrishnan [email protected] 1
Computational Modeling and Nanoscale Processing Unit, Indian Institute of Food Processing Technology (IIFPT), Ministry of Food Processing Industries, Govt. of India, Thanjavur, Tamil Nadu 613005, India
Parboiling of rice is a hydrothermal treatment that involves three major steps: soaking, steaming and drying. During parboiling, gelatinization and retro-gradation of starch occur and therefore, parboiled rice requires longer cooking times. The treatment also alters the structural properties of rice starch, getting conv
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