Symbiotic and adverse interplay of hypogeal germination periods on brown rice (Oryza sativa): nutrient and non-nutrient characteristics

Abstract

This study investigated the symbiotic and adverse consequence of hypogeal germination periods on nutrients and non-nutrient characteristics of brown rice (Oryza sativa). Brown rice paddy was subjected to hypogeal germination for 0–72 h using one-factor design-response surface methodology (OFD-RSM) and evaluated for nutrients and non-nutrient characteristics. The results showed that hypogeal germination caused a significant (p < 0.05) change in the proximate composition: protein (9.42–12.36%), fat (0.88–1.38%), ash (1.87–2.50%); anti-nutrients: saponin (2.03–2.22%), oxalate (2.44–3.45 mg/100 g), phytate (6.99–8.81 mg/100 g); functional properties: water absorption capacity, WAC (121.23–147.78%), oil absorption capacity, OAC (121.39–147.26%); antioxidants properties: 2, 2-diphenyl-1-picrylhydrazyl, DPPH (35.30–43.60%), ferric reducing antioxidant power, FRAP (0.054–0.119 mMolFe2+), metal chelating activity, MCA (44.28–52.99%), total phenolic content, TPC (0.623–0.798 mg gallic acid equipvalent per gram (mgGAE/g)), total flavonoid content, TFC (43.47–50.63 mg rutin equivalent per gram (mgRUTIN/g)); and mineral content: calcium (36.0–41.76 mg/100 g), phosphorus (82.53–94.32 mg/100 g), and magnesium (162.70–168.36 mg/100 g). Germination had significant symbiotic effects (linear and quadratic) on the proximate, DPPH, FRAP, MCA, TPC, WAC, OAC, and anti-nutrients. Whereas, adverse effects (linear and quadratic) of germination were noted in total flavonoids and anti-nutrients. Optimum hypogeal germination period of 72.18 h was established and corresponding protein (12.37 g/100 g), fat (1.37 g/100 g), fibre (2.15 g/100 g), moisture (10.07 g/100 g), DPPH (43.66%), FRAP (0.105mMolFe2+), TPC (0.08mgGAE/g), TFC (50.25MgRUTIN/g), WAC (147.99%), OAC (147.29%), Calcium (41.77 mg/100 g), iron (0.207 mg/100 g), zinc (5.89 mg/100 g), phosphorus (94.77 mg/100 g). Phenolic compounds profile of the optimized germinated brown rice showed the presence of gallic acid (2.84 mg/100 g), 4-hydroxy benzoic acid (3.41 mg/100 g), caffeic acid (4.63 mg/100 g), vanillic acid (6.19 mg/100 g), catechin (3.88 mg/100 g), chlorogenic acid (1.93 mg/100 g), ferulic acid (4.16 mg/100 g), and quercetin (1.27 mg/100 g) whereas, the non-germinated rice showed gallic acid (2.05 mg/100 g), 4-hydroxy benzoic acid (2.53 mg/100 g), caffeic acid (4.11 mg/100 g), vanillic acid (6.08 mg/100 g), catechin (3.35 mg/100 g), chlorogenic acid (1.89 mg/100 g), ferulic acid (4.23 mg/100 g), and quercetin (1.29 mg/100 g). Hypogeal germinated brown rice could find application as a functional ingredient in food formulation.