Abstract:
Thermally processed king coconut (Cocos nucifera var. aurantiaca) water is one of the fastest
growing export commodities in the food and beverage sector in Sri Lanka. Microbial safety of
thermally processed king coconut water is demanded by Food and Drug Administration to ensure
safe consumption. This study aimed to identify potential spoilage and pathogenic microorganisms
associated with king coconut water processed in Sri Lanka. King coconut water samples were
collected at pre-identified sampling points; P1-Nut water extraction, P2-Bulk collection, P3-
Standardization/Acidification, P4-Pre-heating prior to hot filling and P5; Sterilization/Pasteurization
in three processing facilities; F1 (semi-automated), F2 (automated) and F3 (manual), where
Pasteurization (100 °C/12.5 min), UHT Sterilization (140 °C/3s) and Pasteurization (100 °C/20
min) were practiced, respectively. Serially diluted king coconut water were plated on Nutrient Agar,
Potato Dextrose Agar, Eosin Methylene Blue Agar and Reasoner‟s 2A Agar, incubated at 30 ± 1 °C
for 48 h, 25 ± 1 °C for 2 - 5 days, 37 ± 1 °C for 48 h and 37 ± 1° C for 48 h, respectively. Purified
bacterial and fungal colonies were morphologically characterized. A total of 29 bacterial isolates
and 24 fungal isolates were identified by 16S rRNA and 26S/5.8S rRNA/ITS gene amplification,
respectively followed by sequencing using 27F/1492R and ITS-1/ITS-4 primers, respectively.
Evolutionary relationships of identified species were predicted using MEGA 7. The study revealed
that thermal resistant, facultative-anaerobic, spoilage and pathogenic bacteria (Pantoea dispersa,
Bacillus siamensis, Pseudomonas stutzeri, Acinetobacter lactucae) and fungi (Candida carpophila,
Pichia kudriavzevii, Debaryomyces nepalensis, Microdochium fisheri, Penicillium citrinum) were
survived in the thermally processed finished product. Further, potential risk of Klebsiella
pneumoniae, Enterobacter roggenkampii, Enterobacter kobei, Escherichia fergusonii, Bacillus
nealsonii, Serratia rubidaea, Trichosporon asahii, Wickerhamomyces anomalus,
Saccharomycetales species and Fusarium species were identified at initial processing steps (P1-P3)
in studied processing facilities. In conclusion, the study revealed that the existing thermal
treatments are not sufficient for the destruction of identified potential spoilage and pathogenic
microorganisms associated with studied processes. Thereby, suggesting thermal process validation,
while targeting identified potential harmful microorganisms with optimum time-temperature
combinations to ensure product safety.
Keywords: King coconut water; Spoilage and pathogenic microorganisms; Molecular identification;
Thermal processing
