Thermal and ultraviolet-c inactivation of Salmonella enterica in cold-pressed virgin coconut oil

Abstract

Virgin Coconut Oil (VCO) consumption as functional food has recently become popular together with increasing evidence of its health benefits. However, cold-pressed VCO types are highly manually produced without the application of kill step to ensure safety from possible pathogenic contaminants. The study therefore determined the inactivation behavior and kinetic parameters of Salmonella enterica in VCO subjected to mild heat and ultraviolet-c (UV–C) irradiation. When exposed to 50–70 °C, S. enterica exhibited a biphasic inactivation behavior with initial, logarithmic linear population decline of 2.07–2.39 log CFU/mL. An inactivation tail followed where minimal population changes took place. Total inactivated cells ranged from 2.28 to 2.35 log CFU/mL, which were achieved from 2. o to 100 min. Similar behavior was observed in UV-C-irradiated VCO at surface irradiance of 1.25–3.99 mW/cm2. Population decline in the log-linear inactivation phase ranged from 2.59 to 4.00 log CFU/mL, achieved after 0.33–1.20 min. After irradiation for 2.0 min, the total inactivated population ranged from 2.68 to 4.17 log CFU/mL. Complete elimination of S. enterica was not observed in any of the highly contaminated VCOs. These results provide baseline information for the establishment of pasteurization processes to achieve VCO safety.