OPTIMIZATION OF THE EXTRACTION PARAMETERS OF TOTAL PHENOLIC COMPOUNDS FROM QUINOA (Chenopodium quinoa Willd) LEAVES VARIETY INIA 420 – NEGRA COLLANA

Quinoa leaves, rich source of bioactive compounds, vitamins and minerals, are part of the population diet from the Andes since ancient times. In Asia and America it was accustomed to eat this food as salad, and in Peru, quinoa leaves were disposed as anti-inflammatories against toothache, fractures, internal hemorrhage and urinary tract disinfectant. The scarce literature regarding phenolic content and biological activity of quinoa leaves led to the investigation which objective was to optimize the extraction parameters of total phenolic compounds (TPC) in variety INIA 420 – Negra Collana. The physicochemical composition of quinoa leaves presented a moisture (84%), lipid (2%), and protein (1.3%) contents according to the research reports. Optimization of the extraction temperature (25.86 – 54.14° C), ethanol concentration (5.86 – 34.14 %) and extraction time (1 – 105 min), based on a factorial design 22 and subsequent Central Composite Design, showed that total phenolic content (4597.85 mg GAE/100 g) was obtained at the solvent concentration of 30 % and temperature of 50° C with an extraction time of 60 min. The extraction was performed using orbital shaking. The obtained extracts were submitted to the DPPH (2,2 Diphenyl 1 picrylhydrazyl) and TEAC (Trolox Equivalent Antioxidant Capacity) assays, which reported 6414.35 and 5009.97 μmol T.E./100 g, respectively. The correlation between TPC and antioxidant capacity assays showed that there is a higher approach with TEAC (0.94) than DPPH (0.75). The optimization of the extraction parameters demonstrated that quinoa leaves have a phenolic content higher than other leaves from the Chenopodiaceas family like spinach, beetroot and chard, making them an alternative for human consumption. Moreover, TPC content was correlated to its antioxidant capacity. Finally, the investigation could lead to the reuse of quinoa leaves waste after post-harvest of quinoa grains, and to industrial application in the place of origin.