Identification of Potentially Hazardous Microorganisms and Assessment of Physicochemical Deterioration of Thermally Processed King Coconut (Cocos nucifera var. aurantiaca) Water under Different Processing Conditions in Sri Lanka

Abstract

King coconut water (KCW) is a sweet relish product that is more prone to rapid quality deterioration, and several safety concerns are emerging due to its inappropriate thermal processing. Therefore, the objective of this study was to identify the potential spoilage/pathogenic microorganisms associated with the processing of KCW, with the assessment of possible physicochemical changes as providing preliminary information required for the thermal process validation of bottled KCW. Samples (n = 6, 150 ml/sample) were collected from three different KCW processing facilities at five critical processing steps $\left(P_1-P_5\right)$ . A facility survey, physicochemical analyses, and microbial enumeration and isolation, along with their molecular identifications, were conducted. It was found that all tested physicochemical properties were significantly changed $\left(p<0.05\right)$ among sampling points at each processing facility. The colour of thermally processed KCW samples has significantly changed $\left(p<0.05\right)$ compared to the fresh KCW, which causes a distinct effect on the appealing quality of the final product. A pattern of initial lower counts with gradually increased microbial counts at intermediate processing steps (1.0 × 103–5.3 × 106 CFU/ml) and significantly lowered $\left(p<0.05\right)$ counts after thermal treatment was observed. Among the bacterial and fungal isolates identified, several potential pathogenic bacterial species, such as Pantoea dispersa, Bacillus siamensis, Pseudomonas stutzeri, and Acinetobacter lactucae; a few thermal resistant yeasts, Pichia kudriavzevii, Debaryomyces nepalensis, and Candida carpophila; and moulds, Penicillium citrinum, Microdochium fisheri, and Trichosporon asahii, have survived in the thermally processed KCW. Based on the results of the study, it is suggested that the thermal process validation of KCW should be targeted according to the revealed knowledge on the identified hazardous microorganisms, while adhering to Good Manufacturing and Hygienic Practices with minimized handling time to avoid rapid quality deterioration.