Microbial shelf life of coconut water subjected to various inoculation levels of Listeria monocytogenes and storage conditions.

Abstract

The study determined the growth kinetic parameters of a cocktail of Listeria monocytogenes 1/2c and 4b strains in coconut water (pH\xa04.76, 5.0°Brix, 0.09% malic acid, aw 0.998) subjected to low (~2.0 log CFU/mL) and high (~4.0 log CFU/mL) contamination levels, and exposed to different storage temperatures (4\xa0°C, 17\xa0°C, 30\xa0°C, and 35\xa0°C). The pathogen proliferated in all tested conditions except in that with low contamination stored at 4\xa0°C. Despite not growing at 4\xa0°C, the pathogen was detectable throughout the storage period, which lasted for almost 400\xa0h. In conditions where the pathogens proliferated, growth lag (tlag) ranged from 0.0 to 68.3\xa0h. The growth rates (KG) ranged from 0.05 to 0.48 log CFU/h, while the final populations ranged from 6.3 to 8.7 log CFU/mL. Both storage temperature and contamination level significantly (P\xa0<\xa00.05) affected the growth parameters. Sanitary risk times (SRT) were determined with the microbiological shelf life (SL) of coconut water. In some of the conditions tested, SRT took place before SL (SRT\xa0<\xa0SL), emphasizing the importance of having good hygienic and manufacturing practices in place for such a vulnerable commodity.