Abstract
Unsold olive oils stored for long periods are degraded by hydrolysis, resulting in a high level of acidity, leading to loss of economic value of these as a food product. This study was performed to improve the quality of high-acid olive oil (HAOO) and assess the feasibility of deacidification of HAOO using bamboo charcoal as an adsorbent, by applying a stirring technique. Strategies to improve the quality of HAOO, which was obtained by allowing commercial extra virgin olive oil to rest for two years, were tested by measuring free fatty acids, peroxide value, volatile compounds, and chlorophyll and carotenoid pigments. Initially, the effective weight of bamboo charcoal used in the deacidification treatment of HAOO was determined. The level of free fatty acids in the treated oils was effectively decreased with increasing treatment duration. However, bamboo charcoal was not effective in scavenging peroxides in HAOO. In addition, treatment with bamboo charcoal could effectively reduce the level of oxidative off-flavours, such as hexanal. However, the treatment was not effective in reducing chlorophyll and carotenoid pigments. These results suggest that bamboo charcoal may be a good adsorbent and can improve the oil quality of HAOO without changing the appearance of the oil. Consequently, the unsold oils may recover the economic value as a food product, leading to a reduction in their disposal.
