In this study, we have determined, using RSM (mixture design and Doehlert matrix), the optimum values of the independent variables to achieve the maximum response for the extraction of total phenolic compounds from Spondias mombin L bagasse agroindustrial residues in order to preserve their antioxidant activity. The extraction of phenolic compounds, as well as their antioxidant capacity and the capacity to scavenge ABTS, was determined by the modified DPPH method at different periods of time, temperature, velocity of rotation and solvents concentration. We observed that the optimum condition for the highest antioxidant yield was obtained using water (60.84%), acetone (30.31%), and ethanol (8.85%) at 30 • C during 20 min at 50 rpm. We have also found that the maximum yield of total phenolics was 355.63 ± 9.77 (mg GAE/100 g), showing an EC 50 of 3,962.24 ± 41.20 (g fruit/g of DPPH) and 8.36 ± 0.30 (µM trolox/g fruit), which were measured using DPPH and ABTS assays. These results suggest that RSM was successfully applied for optimizing the extraction of phenolics compounds thus preserving their antioxidant activity.

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The optimum extraction conditions for highest recovery of total phenolics content and antioxidant capacities were analyzed for strawberry (Fragaria ananassa) using response surface methodology. Phenolic compounds have been used in food technological processes, and thus it can contribute to the prevention of some degenerative diseases and used as antioxidant or antimicrobial. The assessment of the concentration of total phenolics, as well as their capacity to scavenge ABTS and the antioxidant capacity, determined by the modified DPPH method, were investigated based on distinct combinations of time, temperature, and solvents concentration. It was investigated that the optimum condition for getting the highest antioxidant yield was obtained under water-acetone (80:20, v/v) at 36 ºC and 36 min. We have found that the maximum yield of total phenolic was 1707.66 ± 38.43 (mg GAE/100 g), preserving the antioxidant capacity which was measured by using DPPH and ABTS assays, showing an EC50 of 1085.20 ± 32 (g fruit/g of DPPH) and 66.67 ± 2.4 (μM trolox/g fruit) respectively. This method is also easier and cheaper than other methods to perform polyphenols extractions since does not require expensive reagents or high quantities of organic solvents.

In this study, cashew apple (Anacardium occidentale L.) bagasse, a residue from the industrial extraction of the juice, was subjected to a solid-state fermentation process with the fungus Penicillium roqueforti ATCC 10110 and the total phenolic content was evaluated, as well as the activity of extracts against strains of dermatophyte fungi of the genera Trichophyton and Microporum; cytotoxicity was analyzed through hemolytic potential in human erythrocytes. The results showed that the fermented cashew apple bagasse had a higher content of total phenolics compared to the unfermented bagasse, a potent antifungal activity with minimum inhibitory concentrations (MIC) ranging from 256 to 512 μg/mL against the strains: T. rubrum (LM-115 and LM-629), T. mentagrophytes LM-119, M. gypseum LM-512 and M. canis (LM-68 e LM-110), with low cytotoxicity. Therefore, the fermented extracts of cashew apple bagasse can be considered as a promising natural non-toxic product for studies in the development of agents against skin diseases, especially for the treatment of dermatophytosis.