Integrated Utilization of Guava (Psidium guajava']java L.): Antioxidant Activity of Phenolic Extracts Obtained from Guava Seeds with Supercritical CO2-Ethanol

In this work, it was explored the possibility of obtaining phenolic extracts with antioxidant activity (AA) from Colombian guava seeds (Psidium guajava L.) using supercritical carbon dioxide adding ethanol as cosolvent (SC CO2/EtOH). The crude extracts were obtained by block extraction designs step to step (four steps) as function of pressure (10, 15 and 20 MPa) and temperature (313, 323 and 333 K) (with four different extraction step designs). In each one of the extracts, the total phenolic content (TPC) and AA were determined (beta-carotene bleaching and scavenging DPPH (2,2-diphenyl-1-picrylhydrazyl) methods). This work allowed to obtain a most effective phenolic extract, that presented a most potent antioxidant activity compared toward previous works. The most active extract was subjected to flash chromatography column (FCC), whose process was monitored by thin layer chromatography (TLC), being obtained four fractions. The most active fraction and the best crude extract were tested as potential antioxidant in edible oil (the response variables were the peroxide value (PV) and the conjugated dienes (CD)). It was observed that the fraction IV showed a good performance in preventing the formation of peroxides, while the best crude extract inhibited the degradation of conjugated dienes. The guava seeds are a promising source of antioxidants which can be extracted using SC CO2/EtOH by special extraction step design, these compounds can be used as preservatives in foods such as edible oils.