Efficacy of rice bran fermentation in cosmetics and skin care products

Abstract

This study aims to develop rice bran-based skin care products with moisturizing, whitening and anti-wrinkle effects similar to Pitera (a natural by-product of sake lees fermentation) but without alcohol irritation for sensitive skin. To achieve this objective, bran from organic indica rice was fermented by lactic acid bacteria in a safe and pollution-free environment. In terms of anti-oxidation, the DPPH．free radical scavenging ability of 100.0 mg/mL bran fermentation solution was 71.4% of that of vitamin C of the same concentration; and its Fe²⁺ chelating ability was 79.0% of that of EDTA of the same concentration. Moreover, the superoxide anion scavenging ability of 10.0 mg/mL bran fermentation solution was equivalent to 42.9% of that of BHT of similar concentration. With respect to inhibition of melanin synthesis, the bran fermentation solution's ability to inhibit the synthesis of dopachrome, the intermediate of melanin, was positively correlated to its concentration, i.e., the higher the concentration of the bran fermentation solution was, the better the inhibition ability was. The IC₅₀ of bran fermentation solution was 9.23 mg/mL while, for comparison, that of arbutin was 0.52 mg/mL. Furthermore, according to the cell survival assay, no obvious cytotoxic effect was found with the increase of the concentration of the bran fermentation solution. As for whitening evaluation, the whitening improvement rate was 9.29% in 20% dilution, 5.36% in 15% dilution, 3.69% in 10% dilution, 2.43% in 5% dilution, 0.35% in 1% dilution in a 30-day test. In the moisturizing evaluation, the moisturizing improvement rate was 44.31% in 20% dilution, 20.48% in 15% dilution, 7.68% in 10% dilution, 6.02% in 5% dilution and 2.02% in 1% dilution. Based on the experimental results, the alcohol-free rice bran fermentation solution not only did not cause irritation but also had anti-aging, melanin synthesis inhibition, whitening and moisturizing effects. Therefore, it is advisable to add rice bran fermentation solution to cleaning mousse, shower gel, serum and essence to turn bran from compost of agricultural waste (cradle to grave) into a natural raw material (cradle to cradle) of the cosmetic industry, creating new value of rice bran.