Dados do Trabalho

Título

BIOETHANOL IMPROVES THE ANTIOXIDANT CAPACITY OF OIL EXTRACT FROM BRAZIL NUT CAKE, INCREASING ITS THERMO-OXIDATIVE STABILITY

Introdução

Brazil nut (Bertholletia excelsa) is a valuable source of oil (>60%), rich in unsaturated fatty acids. However, traditional cold pressing extraction shows limited yields. Thus, the oil retained in the cake, nut pressing by-product, deserves attention. Taking this into account, this study investigated the residual oil extraction from Brazil nut cake using hexane (traditional but toxic solvent) and bioethanol, an unconventional and renewable solvent. The commercial oil obtained by cold pressing was used for comparison purposes.

Material e Métodos

The thermo-oxidative stability and antioxidant capacity of the products were evaluated. Oil was recovered by solid-liquid extraction under reflux at 70 °C, using a solid:solvent ratio of 1:15 (g:mL) for 8 hours. Oil/solvent separation was carried out by rotovaporation at 50 °C under vacuum. Thermo-oxidative stability was assessed using the Rancimat method at 110 °C in replicate. Antioxidant capacity was determined by the FRAP method in triplicate.

Resultados e Discussão

Results revealed significant differences (p<0.05) in thermo-oxidative stability and antioxidant capacity among all the oils. The commercial oil showed lower thermo-oxidative stability (7.54±0.08 hours) and antioxidant capacity (64.07±0.52 μm FeSO4/100g) compared to the oils extracted from the cake. The oil extracted with hexane presented an increase in the thermo-oxidative stability (9.68±0.08 hours) and antioxidant capacity (238.79±2.16 μm FeSO4/100g), when compared to the commercial oil. However, the thermo-oxidative stability (24.70±0.45 hours) of the oil extracted with bioethanol was two to three times greater than that of the other two oils, in addition to its antioxidant capacity (408.34±2.15 μm FeSO4/100g) be two to six times greater. Results also indicated a strong positive Pearson correlation between thermo-oxidative stability and antioxidant capacity (r = 0.913).

Conclusão

In other words, bioethanol was able to extract antioxidant compounds present in the cake, possibly due to its polarity. This increased the antioxidant capacity and, consequently, the thermo-oxidative stability of the oil. In conclusion, bioethanol proved to be a promising solvent for the extraction of residual oil from Brazil nut cake with superior quality. This performance could lead to better use of the residue by the food industry and the unprecedented application of bioethanol to extract nut oil.