Improvement of cosmeceutical properties in rice by-products by solid state fermentation with Aspergillus oryzae and effects of different extracting conditions

Abstract

Rice milling generates a lot of rice by-products and they are commonly used as an animal feed ingredient. However, they have high cosmeceutical values, attributed to their high content of bioactive compounds. In the present study, rice by-products (broken rice and rice bran) were subjected to solid state fermentation (SSF) using Aspergillus oryzae at 30° C for 12 days and their cosmeceutical potentials were then evaluated. Different extraction conditions such as the type of solvent (water, 50% ethanol) and extraction temperature (30°C, 40°C) were also optimized using a one-factor-one-time approach. Through tyrosinase inhibition assay, it was observed that SSF has improved the anti-pigmentation effect of broken rice and rice bran 7.4-fold and 11.2-fold in comparison to their unfermented substrate, respectively. SSF has also improved the anti-ageing effect of broken rice and offered 6.6-fold of improvement in fermented rice bran. In extraction optimization studies, a stronger anti-ageing effect was observed in the water extract of both fermented substrates extracted at 40°C while the anti-pigmentation effect is stronger on 50% ethanol extract in fermented rice bran. Most phenolic acids that are commonly related to cosmeceutical purposes were detected in the extracts of both fermented substrates while most of the organic acids were detected in the water extract. Our study suggests that SSF using A. oryzae could improve the cosmeceutical activities of rice byproducts, and both water and 50% ethanol extracts have high potential to be developed as cosmeceutical bio-ingredients.