“Effect of bioprocessing through germination and hydrothermal treatment on nutrients, nutraceuticals, and antioxidant properties in red and black rice”

The study was conducted to investigate the effects of bioprocessing by germination and hydrothermal treatment of pigmented red ( Jyothi ) and black ( Chak hao ) rice paddy on nutrients, nutraceuticals and antioxidant activities in unpolished rice and comparison with the raw unpolished rice. The results of bioprocessing in the red sample showed an increase in gamma-aminobutyric acid (GABA)(117%), γ-oryzanol (46%), soluble phenolics such as gallic acid (GA)(194%), t-cinnamic acid (80%), bound phenolics like GA (1104%), protocatechuic acid (PCA)(66%) and vanillic acid (VA)(55%) and NO scavenging activity (35%) compared to control. In contrast, the black variety showed an increase in GABA (68%), γ-oryzanol (13%), and soluble phenolics like catechin (CAT)(47%), syringic acid (SYN)(148%), PCA (78%), t-cinnamic acid (590%) and bound phenolics like GA (242%), SYN (260%), caffeic acid (CAF)(115%), campesterol (12%) and β-sitosterol (17%) compared to control. Bioprocessing and hydrothermal treatment in red showed no change in GABA and phytosterols, while an increase in γ-oryzanol (39%), total anthocyanin (62%), bound phenolics such as PCA (30%), CAF (17%) and t-cinnamic acid (35%), and NO scavenging activity (13%) compared to bioprocessed rice. In contrast, black showed an increase in GABA (17%), bound phenolics like CAT (167%), t-cinnamic acid (64%), ferulic acid (FA)(79.5%), campesterol (14%), stigmasterol (29%) and β-sitosterol (13%), and NO scavenging activity (26%) compared to bioprocessed rice. Significant retention of total phenolics, flavonoid, γ-tocotrienol, γ-tocopherol, α-tocopherol and phytosterols content, and DPPH radical scavenging and total antioxidant activity in both the samples was observed in-spite of processing compared to control. Changes in the contents of nutrients and nutraceuticals are variety-specific. Bioprocessing and hydrothermal treatment resulted in nutraceutical-rich pigmented whole red and black rice, which can be used to develop functional foods to prevent lifestyle disorders.