The effect of heat treatments on the bioactive compounds, antioxidant activity, and cosmeceutical properties (anti-pigmentation and anti-ageing) of fermented broken rice

Abstract

Previously, broken rice was subjected to solid-state fermentation using locally isolated Aspergillus oryzae under optimised conditions. The fermented broken rice (FBR) has shown great promise as a bioingredient in the formulation of health foods and cosmeceutical products. However, the effects of heat treatment on the bioactive compound content and biological activities of FBR are still unknown. Thus, the goal of this study was to see how different heat treatments affected the bioactive compound content, antioxidant activity, and cosmeceutical properties of FBR, such as anti-pigmentation and anti-aging. This study involved heating FBR at three different temperatures (autoclaving: 105°C, 5–15 mins; pasteurising: 80°C, 90°C, 10 mins; and oven heating: 60°C, 80°C, 24 hrs). The antioxidant activity was measured using ferric-reducing antioxidant power (FRAP), while the anti-pigmentation and anti-aging activities were measured using tyrosinase inhibition and elastase inhibition activity, respectively. High-performance liquid chromatography (HPLC) was used to determine the composition of phenolic acids. Heat treatment at 60°C or 80°C for 24 hrs increases total phenolic content, total flavonoid content, antioxidant activity, anti-pigmentation, and anti-ageing activity in FBR, but oven heating at 80°C for 24 hrs produces the best results of all treatments. Additionally, oven heating at 80 °C for 24 hrs increases the content of gallic acid and syringic acid. However, some phenolic acids, such as p-catechuic, benzoic, and vanillic acids, were reduced at the same temperature. These findings suggested that heating conditions influence FBR's antioxidant activity, cosmeceutical properties, and bioactive compound content. FBR has the potential to be used as a promising bioingredient in the health food and cosmetic industries, given all of the enhanced effects from heat treatment.