Effect of solid-state fermentation on amino acid profile and phytochemicals of red rice bran

Abstract

We aimed to evaluate the effects of solid-state fermentation (SSF) on red rice bran, specifically for a new rice variety (RD69,Tubtim Chumphae) in Thailand. Fermentation of red rice bran with Aspergillus oryzae was continued for 6 days at 30 °C, and LC MS/MS was used to determine the free amino acid composition, antioxidant activity of 2,2-diphenyl-1-picrylhydrazyl, ferric reducing antioxidant power, presence of phenolic and flavonoid compounds, and cytotoxicity in HeLa cells. The results showed that SSF significantly increased (p < 0.05) the total amino acid content by 59.00% after 5 days of fermentation. Fermented red rice bran (FRRB) contained a significant increase (p < 0.05) in antioxidant activity and compounds, which reached their maximum levels by fermentation for 5 days. FRRB also exhibited increased cytotoxicity in HeLa cells compared with unfermented rice bran. The increases of cytotoxicity and antioxidant activities were due to enzymatic hydrolysis and fermentation, in correspondence with the increase in phenolic and flavonoid compounds, suggesting that enzymatic hydrolysis improves the nutritional and phytochemical properties. Notably, the duration of fermentation is a key to optimizing the biological activity of the fermented product.

Exploring the Impact of Fermentation on Brown Rice: Health Benefits and Value-Added Foods—A Comprehensive Meta-Analysis

“…For instance, the phytic acid content decreases by approximately 41%, a reduction deemed highly effective as cited in the Food Chemistry journal [3]. Solidfermented brown rice exhibits a similar decrease in phytic acid [11]. Additionally, while brown rice is a recognized source of oryzanol and the vitamin E isoform, fermented brown rice shows a significant increase in levels of -tocotrienols, with a marked decrease in levels of -tocopherols [3].…”

“…GABA, for example, is known for its potential anti-diabetic effects. Furthermore, fermentation in brown rice alters its dietary fiber, potentially improving its beneficial impact on post-meal glucose responses [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. This process also reduces anti-nutritional factors, such as phytic acid, which hinders mineral absorption but is degraded during fermentation.…”

“…Cancer primarily results from the unchecked proliferation of abnormal cells leading to tissue damage. According to the World Health Organization (WHO), cancer ranks as the second leading cause of death globally, with projections suggesting approximately 10 million cancer-related fatalities in 2020-this accounted for one in every six deaths [11]. Consequently, substantial research into naturally occurring substances was necessary to prevent and mitigate cancer incidence.…”

“…Rice is a staple food consumed globally. Although various cooking methods can diminish some of its nutritional value and quality, brown rice, with its bran layer, offers distinct nutritional advantages [11]. However, the presence of this bran layer can prolong cooking time and result in a coarser texture compared to white rice.…”

“…This is because the wheat grains are removed during the milling process to produce white rice, leading to a significant wastage of rice bran [28,31]. Moreover, fermented brown rice not only boosts nutritional value by altering rice's nutritional composition and increasing its beneficial content but also contains a substantial number of phenolic chemicals and plant polyphenols [1,7,11]. This rice variant further offers health advantages by preventing various diseases, thanks to its antioxidant [1,15], antidiabetic [21,22], anti-obesity [15], and anti-inflammatory [27,28] properties.…”