Effect of Parboiling Conditions on Physical and Cooking Quality of Selected Rice Varieties

Abstract

Most locally cultivated rice varieties in Ethiopia have low physical (low head rice yield, high broken rice yield, and high percentage of chalkiness) and cooking qualities (low water uptake ratio and swelling ratio). Parboiling, a process which involves soaking, steaming, and drying, has been identified as a key technique to improve cooking and milling quality of rice. The current study is aimed at elucidating the effect of parboiling on physical and cooking qualities of three rice varieties (Gumara, Edget, and Narica4) collected from Fogera National Rice Research and Training Center, Amhara region, Ethiopia. Each rice variety was subjected to different soaking temperatures (40°C, 50°C, 60°C, 70°C, and 80°C) and steaming time (10, 20, 30, 40, and 50 minutes). The treatment effect results indicated that parboiling has a significant effect (P<0.05) on head rice yield and percentage of broken rice with increased soaking temperature and steaming time as compared to the control. For instance, percent head rice yield increased as soaking temperature (from 40 to 80°C) and steaming time (from 10 to 50 min) increased: for Gumara, from 4.07 to 93.6%, for Edget, 9.47 to 96.53, and from 3.20 to 91.67 for Narica4. Percentage chalkiness had decreased as soaking temperature and steaming time increased: 97.33% to 0.00% for Gumara, 97.80% to 0.00% for Edget, and 100.00% to 0.13% for Narica4 as compared to 100% for control of all varieties. The minimum cooking time was identified as 16-23 min for Gumara, 16-23 min for Edget, and 15-20 min for Narica4 rice varieties. The result of the present study clearly showed that parboiling with high soaking temperature and steaming time increased the head rice yield, water uptake ratio, decreased percentage chalkiness, and enhanced the overall quality of the rice varieties.

Optimization of soaking conditions (temperature and time) on physicochemical properties of selected parboiled rice varieties grown in Eastern Ethiopia

“…The results showed that the cooking time increased as the soaking temperature and soaking time were increased. The found results in contrast with Meresa et al ( 2020 ) studied that the minimum cooking times of Ethiopian rice varieties were identified as 16–23 min for Ediget and 16–23 min for Gumara rice varieties when soaked at 40–80°C for 10–50 min. The variation in cooking time might be due to differences in genetic makeup and microwave‐assisted parboiling equipment which are significantly decreased the cooking time of the rice grains (Rockembach et al, 2019 ).…”

“…The results showed that the cooking time increased as the soaking temperature and soaking time were increased. The found results in contrast with Meresa et al (2020)…”

“…Parboiling is a process designed to improve the quality of rice and consists of soaking, steaming, and drying operations (Buggenhout et al, 2014 ). Parboiling is identified as a key technique to improve the physical properties, nutritional value, and cooking quality of rice (Meresa et al, 2020 ). Soaking is a hydration method in which water is absorbed through diffusion and then migrates into the rice kernel (Mir & Bosco, 2013 ).…”

“…In Ethiopia, most scientific information was published on the effect of parboiling conditions on rice's physical and cooking quality (Abera et al, 2021 ; Meresa et al, 2020 ). Nevertheless, there is a piece of limited scientific information on the optimization of conventional soaking time and temperature on the physicochemical properties of selected parboiled rice varieties (NERICA‐4 and NERICA‐6) grown in Eastern Ethiopia.…”

Rice quality and its impacts on food security and sustainability in Bangladesh

“…The chalk percentage ranged from 0 percent to 89.56 percent, with an average of 12.56 percent. The large variability is partially explain by the fact that our samples include parboiled rice, which has a low chalk rate as the parboiling process decreases chalkiness [36]. The average chalk rate of the samples corresponds to sub-standard rice according to the Bangladesh standard [29].…”