ORA-PRO-NOBIS PROTEIN EXTRACTION: PRECIPITATION METHODS AND EVALUATION OF TECHNO-FUNCTIONAL PROPERTIES

The Ora-pro-Nobis (OPN- Pereskia aculeata Miller) is a non-conventional plant, native from South America that has unexplored potential. Their leaves have been gaining recognition due to their protein amount (19.6 % - 26 %), being popularly known as the "meat of the poor". Protein extracted from green leaves has been studied for its potential to be used in foods, however no commercial processes or products are available at the moment, due to the difficulty to extract functional proteins with acceptable yields of these green leaves. Therefore, this work aimed to extract, separate, concentrate and characterize OPN proteins for use as technological substitutes in animal protein-free foods. The OPN protein was obtained by OPN fresh leaves from solubilization of protein (pH 10/60ºC/2h) and precipitation was determined in three different ways: by isoelectric precipitation pH 3.0 (sample A); ammonium sulfate precipitation (sample S) and ammonium citrate precipitation (sample C). The protein solubility was determined as a function of pH (2 to 10). The emulsion activity index (EAI) and emulsion stability index (ESI) of samples A, S and C were determined in sunflower oil/water emulsion with 1.0 % of protein concentration. The results showed that an increase in pH (pH 8.0) enhanced the protein solubility by almost 10 % when compared to pH 6.0 for all the samples A, C and S. At the highest protein solubility in pH 8,0 was for sample A (83.87 ug/100uL) compared with sample C (76.34 ug/100uL) and S (79.67ug/100uL). The OPN protein solubility observed in sample A was lower than soy commercial protein, however, it is still higher than a pea and wheat commercial protein at the same pH and concentration. The lowest EAI was observed in sample S (EAI = 2.11 m²/g), it was observed an increase in the effect on the EAI (4.26 m²/g) in sample A. The ESI was 32.86, 46.71 and 48.63 min, for samples S, C and A, respectively. Overall, the results indicated the best method for extraction and precipitation of OPN proteins, from a techno-functional overview, was by isoelectric precipitation at pH 3.0 (sample A). Furthermore, the OPN protein could be a great alternative for developing new food ingredients used in a wide range of plant-based food products.