Optimization through Response Surface Methodology of dynamic maceration of olive (Olea europaea L.) leaves

Bioactive compounds derived from plants are secondary metabolites that can act as antioxidants and antimicrobial agents. Combined with the pressure generated by consumers for more natural products with beneficial effects on health, these compounds may be suitable candidates to act as preservatives in food products. For this purpose, the extraction process becomes essential for the acquisition of a quality extract with efficiency and with the desired final properties. Therefore, the main objective of this work was to perform the optimization of the extraction yield of olive leaves (Olea europaea L.), by applying Response Surface Methodology (RSM) and employing dynamic maceration as extraction technique. Three factors were analyzed: time (F1), temperature (F2) and solvent (F3), ranging from 5 to 120 minutes, 25 to 100 ºC and from 0 to 100% ethanol, respectively. The study used the Box Behnken design, relying on 17 individual randomized runs. The response was the dry weight of the extract (Y1), which ranged from 21.1 to 90.5 mg. The optimization studies pointed to the increase of yield with the increase of time and temperature, but inversely by applying higher time and lower temperature values, and higher temperature and lower time values. The highest yield of the dry extract was achieved at 120 min (F1), 25 ºC (F2) and 87% (F3) of ethanol:water. For industrial applications, the optimum point temperature of 25 ºC is the most advantageous factor of the maceration, because it avoids complementary expenses for heating the extractive solvent, reducing costs. Future studies will be carried out to analyze the preservative effects of incorporating olive extract in foods, as well as analysis of other response for optimizing the best food preserving extract.