Title : Application of potato (Solanum tuberosum L.) peels as an antioxidant in yogurt formulation
The aim of this work was to optimise the extraction parameters for phenolic compounds from potato (Solanum tuberosum L.) peels (PP) using response surface methodology (RSM). A central composite design (CCD) was used to establish the impacts of ethanol concentration (%), extraction time (min), and solid/luiqid ratio (g/mL). The optimal experimental conditions allowing a maximization of the extraction are the solvent (ethanol) at a concentration of 80% (v/v) for a time of 150 min with a ratio of 1 g/30 mL. Optimal contents of total phenolic (TPC) and total flavonoid (TFC) were 204.41± 8.64 mg EAG/100 g DW and 21.47± 0.76 mg EQ /100 g DM, respevtively. The PP extract has potent antioxidant activity in molybdate and DPPH• assays with IC50 of 10.65 ± 0.21 and 179.75±3.18 µg/mL, respectively. The yogurts formulated with PP revealed significantly higher (P ≤ 0.05) TPC, TFC and antioxidant power than the control sample. In addition, the taste test demonstrated that the yogurt enriched either by PP flower and their dried pieces are the most prefered (67%) than the control yogurt (33%). Our findings prove PP waste is a good source of antioxidants capable of enriching and protecting yogurt, while served to the revaluation of these agrifood by-products.