Estudo da vida útil do azeite extravirgem e da extração por ultrassom de extrato lipídico de bagaço de oliva

Abstract

The production of olive oil has developed in Brazil and especially in Rio Grande do Sul. The quality of olive oils, as well as their shelf life, are important aspects to be considered. The study of shelf life is necessary to understand the reactions and degradation factors of olive oil and thus determine the time for its shelf life. The processing of olive oil generates olive pomace and wastewater as waste. Olive pomace has been used as an organic compound, but it is a source of a lipid fraction. The objective was to investigate the quality parameters of commercial extra virgin olive oil produced in the Campanha Region in Rio Grande do Sul during storage, and the ultrasound-assisted extraction method to recover the lipid extract of olive pomace from the residue of the olive oil agroindustry. . Commercial olive oil was characterized at zero time, compared to the criteria and limits recommended by national and international bodies. The oil was kept for 18 months with the incidence of natural and artificial light during the day and in the dark at night, at room temperature (16.1 to 26.5°C), during which time it was evaluated for quality parameters established by Brazilian legislation, and the total phenolic compounds. The oil remained stable until the 8th month when it presented a value of 0.23 for an extinction coefficient at 270nm, in the 14th month with 2.52 for an extinction coefficient at 232nm and in the 17th month with a free acidity of 0.90% in ac, oleic. The chemical changes observed up to the 18th month showed deterioration and compromised the quality of the oil, although it does not classify it as unfit for consumption. The in natura olive pomace resulting from the extraction of olive oil by the two-phase process and the lyophilized pomace were characterized, presenting, respectively, 70.77 and 7.25% of moisture, 1.52 and 2.48% of ash, 7 71 and 22.57% of lipids, 1.48 and 11.93% of proteins, 7.84 and 24.87% of crude fiber and 10.68 and 30.95% of other carbohydrates; the antioxidant activity was also evaluated, which was 93.27 and 91.22% of inhibition (radical DPPH● ) and the total content of phenolic compounds, which was 65.17 and 111.22 mg EAG 100g-1 of oil. To obtain the bagasse lipid extract by ultrasound, the lyophilized bagasse was added with solvent (ethanol) and subjected to sonication at different bagasse:solvent ratios (1:2 to 1:18), times (30 to 60 minutes) and temperatures of extraction (30 to 60°C), according to a complete factorial experimental design (23). Response variables were lipid extract yield, total phenols and antioxidant activity. In the extraction of lipid extract from olive pomace, the highest yield was 44.41% in the treatment where the proportion was 1:10, time of 45 min and temperature of 45ºC. The recovery of phenolic compounds from the lipid extract of olive pomace obtained better results in the treatment with 130.62mg of EAG 100g-1 of oil in the proportion of 1:2, time of 60 min and temperature of 30ºC. The antioxidant activity of the lipid extract was preserved in all working conditions studied, demonstrating the effectiveness of the method that did not degrade compounds of interest for this parameter.