Cosmetic potential of lignin extracts from alkaline-treated sugarcane bagasse: Optimization of extraction conditions using response surface methodology

Each year, sugarcane bagasse, a low-priced by-product of the sugar industry, is generated in large quantities. The aim of this study was to optimize the alkaline hydrolysis condition for the extraction of lignin from sugarcane bagasse using response surface methodology combined with Box-Behnken design, and to evaluate functional properties of lignin extracts for cosmetic applications. Three process parameters were varied (NaOH solution concentrations (3-7% w/v), temperatures (115-135 degrees C), and times (30-60 min)). The second-order polynomial model developed and the subsequent ANOVA test showed that the optimal conditions providing the highest total phenolic content (69.41 +/- 0.32 mg gallic add equivalent/g extract), antioxidant activity (262.30 +/- 2.98 mg Trolox equivalent/g extract), and sun protection factor (8.65 +/- 021) were as follows: NaOH solution concentration of 7% w/v, temperature of 135 degrees C, and time of 47.92 min. Fourier-transform infrared spectroscopy analysis revealed the functional groups present in the lignin extract that affected its activities. The extract showed both UVA and UVB-absorbing properties and tyrosinase-inhibitory properties. The results suggested that the lignin extract obtained from alkaline hydrolysis of sugarcane bagasse has great potential as a bioactive multi-functional ingredient that can offer anti-ageing, sun-protection, and skin-whitening properties for sun care formulations. (C) 2020 Elsevier B.V. All rights reserved.