Impact of cooking, parboiling and fermentation on nutritional components, predicted glycemic index and pasting properties of rice

Abstract

The impacts of different methods of rice grain processing like cooking, parboiling and fermentation on various bioactive components, antioxidant activity, predicted glycemic index (pGI), resistant starch (RS) along with pasting properties in three rice cultivars were investigated. Results showed that processing significantly increased the DPPH and FRAP antioxidant activity, soluble sugars (TSS), Phenolics, flavonoids and zinc (Zn) content, while protein, amylose, iron (Fe) content and ABTS antioxidant activity decreased as compared to raw unprocessed rice. Percent decrease of these components was minimum in case of parboiling as compared to raw rice. The percent increase of TSS was highest in raw fermented rice while lowest in parboiled fermented rice. Scanning electron micrograph of grain showed that cultivar CR Dhan 310 contains higher amount of protein bodies and after parboiling it increased marginally. The processing significantly decreased the pasting viscosity as compared to raw rice. The average pGI value of parboiled cooked rice(PCR) was lowest while raw fermented(FR) was highest. PCR of Naveen showed highest RS(2.7%) content whereas fermented rice of Manipuri black showed lowest value (0.31%). This finding will help rice consumers to select appropriate processed rice for getting maximum value addition in terms of nutritional quality.