Abstract Melastoma malabathricum is one of the medicinal plants plated in West Kalimantan, Indonesia. Its leaves extraction using organic solvents revealed bioactive compounds and antioxidant activity. However, the antioxidant activity, toxicity, and chemical profile of water extract of M. malabathricum leaves are still unknown. This study aimed to determine extraction conditions that provide water extract of M. malabathricum with the highest antioxidant activity and the lowest toxicity. The extraction conditions were conducted at different water temperatures (25 ± 2 ºC and 90 ± 2 ºC), concentrations (10 and 5 g leaves/100 mL water), and extraction time (15, 30, and 45 minutes). Data analysis was performed by one-way ANOVA followed by Duncan's test (p < 0.05). The result showed that M. malabathricum leaves of 5g/100 mL extracted with hot water (90 ± 2 ºC) for 15 minutes showed the highest antioxidant activity (IC50 2.13 ± 19.20 ppm), which was higher than vitamin C (IC50 4.32 ± 0.16 ppm), and low toxicity (LC50 333.06 ± 99.45 ppm). Six compounds namely, 4-O-caffeoylquinic acid, quercimeritin, digiprolactone, 3-O-trans-coumaroylquinic acid, norbergenin, and arteamisinin were identified for the first time in the water extract of M. malabathricum leaves. These compounds, individually or extracted from other ingredients, have previously been reported to have antioxidant activity.

Abstract Germination can alter the physicochemical, nutritional, and nutraceutical value of brown rice. This study aimed to evaluate some characteristic changes from five Indonesian brown rice varieties during germination. The germination was carried out through a complete soaking method for up to 120 h, and the samples were taken and analyzed every 24 h. The results showed that germination increased GABA (γ-aminobutyric acid) content in brown rice. The highest level of GABA, up to 126.55 mg/100 g, obtained in rice var. Inpari 43, after 120 h. Germination also affected the changes in phenolic content, antioxidant capacity, and γ-oryzanol, while fatty acid compositions showed no changes. The pasting properties changed significantly after germination, especially in peak viscosity, final viscosity, breakdown, and setback. In conclusion, the changes in brown rice characteristics during germination, especially for increased GABA content and shifting of pasting properties, are valuable information for developing functional rice-based food products.

Abstract The purpose of this study was to compare the characteristics of flakes rice made pigmented and non-pigmented glutinous rice grain on chemical composition, fatty acid, amino acid, dietary fiber, and antioxidant properties. Flakes glutinous rice (FGR) made glutinous rice grain that has been pre-roasted and then flattened. This product contains an endosperm and rice bran layer. So that, it is rich in nutrients and bioactive compounds that have antioxidant properties that are beneficial to health. The process of making flakes rice is carried out in four stages, that is the process of soaking, roasting, flattening, and sifting process. The grain used in this study are pigmented (red and black) and non-pigmented glutinous rice grains. The results showed that black FGR contained higher ash content, crude protein, dietary fiber, total phenolic compounds, flavonoids, γ-oryzanol, anthocyanins, and antioxidants activity. Meanwhile, white FGR is highest in fat, carbohydrate, and amylose content amongst others. Furthermore, FGR is rich in essential fatty acids (oleic and linoleic), glutamic acid, essential amino acids (Leucine, Arginine, and Phenylalanine). In conclusion, pigmented FGR has higher nutritional value, antioxidant properties, and antioxidants activity than non-pigmented FGR.