Impact of germination on the techno-functional properties, nutritional composition, and health-promoting compounds of brown rice and its products: A review

Rice is a popular grain and forms part of the daily diet of people throughout the world. However, the consumption of rice and its products is sometimes limited by its high glycemic index due to its high starch content, low protein content and quality, and low bioavailability of minerals due to the presence of anti-nutritional factors. This has partly stimulated research interest in recent times toward the use of bioprocessing techniques such as germination as cheap and natural means to improve the nutritional quality, digestibility, and health properties of cereals, including rice, to partially achieve nutrition and food security in the developing regions of the world. This review highlights the impact of germination on the nutritional quality, health-promoting properties, and techno-functional characteristics of germinated brown rice grains and their products. The review demonstrated that germinated rice grains and their products have improved nutritional quality and digestibility, modified functional properties, and showed antioxidant, anti-inflammatory, anti-diabetic, anti-obesity, anti-cancer, and anti-cardiovascular activities. Germination appears to be a suitable bioprocessing method to improve the nutritional quality and bioactive constituents and modify the techno-functional properties of rice grains for diverse food applications and improved global nutrition and food safety.

Bioactive Compounds and Quality Evaluation of Red-Pigmented Rice Processed by Germination and Roasting

Red-pigmented rice was germinated and processed to develop germinated red rice tea, and the changes in physicochemical, bioactive, and microbial properties due to germination and roasting were investigated. The moisture and crude ash contents of red rice decreased after germination and roasting. Crude protein and crude fat contents increased after germination but slightly decreased after roasting. Total phenolics, flavonoids, and antioxidant activities (DPPH and ABTS radical scavenging activities) increased following germination and heat treatment. However, the increased levels of γ-amino butyric acid after germination significantly decreased during the subsequent roasting step. In addition, total bacteria, yeast, and mold counts increased during the germination process but decreased after heat treatment as compared to those in the original grain; Escherichia coli was not detected. Therefore, germination and subsequent roasting could effectively enhance the contents of the most bioactive compounds and maintain microbial stability in red-pigmented rice.

Changes in Bone Metabolism and Antioxidant Defense Systems in Menopause-Induced Rats Fed Bran Extract from Dark Purple Rice (Oryza sativa L. Cv. Superjami)

Menopause is a matter of concern for women’s health due to a deficiency of female hormones; additionally, reactive oxygen species and aging can cause osteoporosis. Food becomes increasingly interesting as a menopausal woman’s alternative to hormone therapy. The effects of ethanol extracts from dark purple Superjami rice bran on bone metabolism and antioxidant defense systems in menopause-induced animal models were evaluated. Female rats underwent sham surgery or were ovariectomized to induce a menopause-like state. Rats were divided into a sham control group (SHAM), an ovariectomized control group (OVX), and an ovariectomized grou supplemented with Superjami rice bran extract group (OVX-S) and fed for 8 weeks. The OVX groups exhibited significantly more weight gain, amounts of bone turnover biochemical markers (alkaline phosphatase, osteocalcin, and C-terminal telopeptide), bone loss, lipid-peroxidation and oxidative stress than the SHAM group. However, Superjami bran extract added to the diet resulted in a significant reduction in body weight and lipid peroxidation, as well as enhanced bone metabolism and antioxidant enzyme activities, in ovariectomized rats. These results propound that extracts from Superjami rice bran have therapeutic potentiality against bone loss and oxidative stress in menopause-induced states and will be useful in preventing postmenopausal osteoporosis and oxidative damage.

Effect of Germinated Pigmented Rice "Superjami" on the Glucose Level, Antioxidant Defense System, and Bone Metabolism in Menopausal Rat Model

Women experience physical, mental, and social changes during menopause. It is important to maintain a healthy diet for effective menopause management. The effect of germinated Superjami, a deep violet colored rice cultivar, on the body weight, glucose level, antioxidant defense system, and bone metabolism in a menopausal rat model was investigated. The animals were randomly divided into three groups and fed with a normal diet (ND), a control diet supplemented with 20% (w/w) non-germinated Superjami flour (NGSF), or germinated Superjami flour (GSF) for eight weeks. The NGSF and GSF groups exhibited significantly lower body weight and fat, glucose and insulin contents, adipokine concentrations, and bone resorption biomarker levels, and higher antioxidant enzyme activities and 17-β-estradiol content than the ND group (p < 0.05). The GSF group showed greater glucose homeostasis, antioxidative, and bone metabolism-improving effects compared with the NGSF group. These findings demonstrate that germination could further improve the health-promoting properties of Superjami and that this germinated pigmented rice cultivar could be useful in the treatment and management of menopause-induced hyperglycemia, oxidative stress, and bone turnover imbalance.

Germinated Pigmented Rice (Oryza Sativa L. cv. Superhongmi) Improves Glucose and Bone Metabolisms in Ovariectomized Rats

The effect of germinated Superhongmi, a reddish brown pigmented rice cultivar, on the glucose profile and bone turnover in the postmenopausal-like model of ovariectomized rats was determined. The ovariectomized Sprague-Dawley rats were randomly divided into three dietary groups (n = 10): normal control diet (NC) and normal diet supplemented with non-germinated Superhongmi (SH) or germinated Superhongmi (GSH) rice powder. After eight weeks, the SH and GSH groups showed significantly lower body weight, glucose and insulin concentrations, levels of bone resorption markers and higher glycogen and 17-β-estradiol contents than the NC group. The glucose metabolism improved through modulation of adipokine production and glucose-regulating enzyme activities. The GSH rats exhibited a greater hypoglycemic effect and lower bone resorption than SH rats. These results demonstrate that germinated Superhongmi rice may potentially be useful in the prevention and management of postmenopausal hyperglycemia and bone turnover imbalance.