Potencial antioxidante, antimicrobiano e alimentício das folhas de ora-pro-nóbis (pereskia aculeata mill.)

Abstract

“Ora-pro-nóbis” is the common name of Pereskia aculeata Miller, originating in Central and South America, which has a high protein content and is known for its beneficial effects on human health. This cactacea fits in the Non-Conventional Food Plants and is not much exploited in the Brazilian diet. The aim was to investigate the antioxidant and antimicrobial potential through different natural extracts from lyophilized leaves and develop a plant-based product. “Ora-pro-nóbis” leaves were collected on a private property in Rosário do Sul, sanitized, lyophilized and mixed in a 1:20 ratio with the solvents hydroalcoholic solution (70%) and distilled water. The extracts were protected from light and, on the third day, the tubes were placed in an orbital shaker for 24 hours, at 130 rpm, at a temperature of 84,2°F ± 35,6°F. The extracts followed two methods: filtration in the biological safety cabinet and centrifugation for 15 minutes at 10,000 rpm, at 39,2°F. Finally they were stored at room temperature. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azino-bis-3- ethylbenzothiazolino-6-sulfonate (ABTS) assays were applied to measure the antioxidant activity. Antimicrobial activity was performed using the qualitative disk diffusion test against Gram positive and Gram negative bacteria. The formulation of the “Ora-pro-nóbis” pâté had as one of the ingredients fresh leaves of the plant. Sensory evaluation was carried out with untrained tasters, through acceptance and purchase intention tests. The results showed that Pereskia aculeata is a good alternative to synthetic antioxidants. Aqueous and hydroalcoholic extracts (70%) obtained showed antioxidant potential by the DPPH and ABTS methods. In ABTS methodology, all extracts showed percentage of inhibition, ranging from 56% to 91.38%, while in DPPH only the centrifuged hydroalcoholic extract, filtered hydroalcoholic extract and the cold centrifuged aqueous extract showed percentage of inhibition, showing once again the importance of applying more than one technique in the antioxidant potential. When analyzing the antimicrobial activity against the tested bacteria, halos were observed only in the hydroalcoholic extracts with values from 1.8 mm to 3.2 mm, which probably occurred, due to the presence of the hydroalcoholic solution. Based on this, additional tests with increased plant:solvent ratio and with in natura plant extracts are needed to verify the antimicrobial activity. The food product based on “Ora-pro-nóbis” leaves obtained good acceptability, with average values (n=53) between 7.06 and 7.81 for the different sensorial parameters evaluated, which indicates "I liked it regularly" and "I liked it a lot". The purchase intention was 4.05 and signals "I would probably buy this product". “Ora-pro-nóbis” leaves presented antioxidant potential and food potential in a formulation with a vegetable basis, which is interesting for the consumer for preserving the properties of the plant and providing a food source of proteins and beneficial compounds to health, as well as diversifying with non-conventional foods.