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Cited by 14Coconut Research and ApplicationsFood Safety and HygieneListeria monocytogenes in Food Safety

Potential Bacterial Health Risk Posed to Consumers of Fresh Coconut (Cocos nucifera L.) Water

Open access
Awua, Adolf K., Doe, Edna D., Agyare, Rebecca·2012·Food and Nutrition Sciences
DOI 10.4236/fns.2012.38149
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Abstract

Coconut (Cocos nucifera L.) water is a refreshing drink consumed mostly directly from the fruit. However, in recent times, consumers in Accra prefer to have it transferred into plastic bags for later consumption; this favours a high risk of bacterial contamination. Since it is rich in nutrient, it may become unwholesome with possible high bacteria loads. However, its use for managing and preventing diarrhoeal diseases and the report that coconut water contains anti-bacterial proteins, suggests a bacteria growth inhibition potential for it. Therefore, the propensity of fresh coconut water to support the growth of two pathogenic bacteria was studied. Using mostly optical density measurement, and where possible, growth parameters and bacteria loads were estimated for the growth of two gram negative bacteria in fresh, stored and sterilized coconut water, and also in Luria-Bertani (LB) broth as a control. The study revealed that fresh coconut water is a drink favourable for the survival and growth of Escherichia coli, and Klebsiella pneumoniae. It supported the growth of these bacteria recording lag times of 101.4 ± 1.00 minutes for E. coli and 154.8 ± 0.45 minutes for K. pneumoniae, and high loads of viable cells of ~ 2.27 × 108 cfu/mL and > 2.83 × 108 cfu/mL at the stationary phase for E. coli and K. pneumoniae respectively. These and other growth parameters in coconut water were comparable to those in Luria-Bertani (LB) broth medium. However, when autoclaved, gamma irradiated or stored at 4℃ for two weeks or more, the growth of these bacteria becomes extremely limited. Fresh coconut water will support the growth of these bacteria to high and infective load of viable cell if it becomes contaminated with and is kept at ambient temperatures for two or more hours. Thus, it will be safer to consume coconut water directly from the fruit, since there is a high risk for bacteria contamination associated with the transfer and storage in other containers.

AI snapshot

Written from the paper’s full text.

TL;DR

Fresh coconut water supported the survival and growth of *Escherichia coli* and *Klebsiella pneumoniae* to high, potentially infective loads, with growth parameters comparable to Luria-Bertani broth. Autoclaving, gamma irradiation, or storage at 4°C for two weeks or more greatly limited growth, so the authors recommend consuming coconut water directly from the fruit.

Key findings

  • Fresh coconut water supported growth of both bacteria: lag times were 101.4 ± 1.00 min for *E. coli* and 154.8 ± 0.45 min for *K. pneumoniae*, with stationary-phase loads of ~2.27 × 10⁸ cfu/mL and >2.83 × 10⁸ cfu/mL, respectively.
  • Growth in fresh coconut water was comparable to LB broth: *E. coli* growth rates were 0.142 ± 0.0004 OD/h in fresh coconut water vs. 0.463 ± 0.002 OD/h in LB; *K. pneumoniae* rates were 0.216 ± 0.002 OD/h vs. 0.350 ± 0.0019 OD/h.
  • Growth was extremely limited in autoclaved, gamma-irradiated, or 4°C-stored coconut water; *E. coli* showed no exponential growth in irradiated or stored coconut water, and *K. pneumoniae* remained stationary in irradiated and autoclaved coconut water.
  • The authors conclude that contaminated fresh coconut water kept at ambient temperature for two or more hours can reach high infective loads, and recommend direct consumption from the fruit.

Methods

  • Coconut water was extracted and sterilized as previously reported; stored coconut water had been kept at 4°C for two weeks. Sterility was tested by inoculating LB broth and incubating coconut water aliquots.
  • Standard strains *K. pneumoniae* ATCC 33495 and *E. coli* ATCC 25922 were inoculated into LB broth and fresh, stored, autoclaved, and irradiated coconut water, then incubated at 37°C and 125 rpm. Growth was followed by optical density at 686 nm every 30 min for up to 6 h, with viable counts on plate count agar.
  • Descriptive statistics were obtained in MS Excel, and student t-tests compared lag time, growth rate, and maximum growth between LB broth and fresh coconut water.

Limitations

  • The paper states that the possible contributions of antibacterial peptides and other growth-limiting substances in coconut water cannot be determined or evaluated from these results, and calls for further study controlling initial pH and measuring free radicals and nutritional content.
  • Evident from the text: only two gram-negative laboratory strains were tested, the study did not directly sample coconut water sold by vendors, growth was followed for no more than 6 h, and the exact maximum growth of *K. pneumoniae* in fresh coconut water was not attained within the incubation period.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.4236/fns.2012.38149

Cites

18 of 18 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

2 of 21 cited sources checked · 1 supported · 0 flagged · accuracy not yet measured

  • Findingown data

    The growth rate of E. coli in fresh coconut water was 0.142 ± 0.0004 OD units/h.

    “fresh coconut water (0.142 ± 0.0004 OD units/h)”
    • Also stated in: § 4. Discussion · plain
      “OD/h 0.463 ± 0.002 0.142 ± 0.0004 0.181 ± 0.0005”
    Quote in the paperSubstantial claim
  • Findingown data

    The maximum growth of K. pneumoniae in LB broth was 0.666 ± 0.0001 OD units.

    “Ave.OD. at SP 0.666 ± 0.0001 >0.850”
    Quote in the paperNot a substantial claim
  • Findingown data

    Growth parameters of E. coli and K. pneumoniae in coconut water were comparable to those in Luria-Bertani (LB) broth.

    “These and other growth parameters in coconut water were comparable to those in Luria-Bertani (LB) broth medium.”
    Quote in the paperSubstantial claim
  • Findingown data

    The growth rate of K. pneumoniae in LB broth was significantly higher than in fresh coconut water by about 61.7% (p < 0.05).

    “The growth rate of K. pneumoniae in LB broth (0.350 ± 0.0019 OD units/h) was significantly higher than that in fresh coconut water (0.216 ± 0.002 OD units/h) by about 61.7% (p < 0.05)”
    Quote in the paperSubstantial claim
  • Findingown data

    The growth rate of K. pneumoniae in fresh coconut water was 0.216 ± 0.002 OD units/h.

    “fresh coconut water (0.216 ± 0.002 OD units/h)”
    • Also stated in: § 4. Discussion · plain
      “OD/h 0.350 ± 0.0019 0.216 ± 0.002”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim. 6
  • May combine two claims. 11

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    The amount of total carbohydrate in fresh coconut water was higher than that of autoclaved coconut water, although the difference was not significant.

    “It is worth noting as reported earlier [12] that the amount of total carbohydrate in fresh coconut water was higher than that of autoclaved coconut water, although the difference was not significant.”
    Quote in the paperNot a substantial claim1 of 1 sources checked

  • May combine two claims.

    Premisecitation

    The initial pH of LB broth was 7.0, fresh coconut water 6.5, and autoclaved coconut water 5.0.

    “the initial pH of LB broth was 7.0, optimal for the growth of E. coli (survive between pH 4.5 and 9.0), while those for fresh and autoclaved coconut water were slightly below the optimal (6.5 and 5.0 respectively).”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [12] source

      Table 2 in Results > Changes in pH lists initial pH as 6.0–6.5 for fresh coconut water and 5.0 for autoclaved coconut water, supporting the coconut-water values, though 6.5 is the upper end of the fresh-water range rather than its average. The paper mentions LB broth as a sterility-testing medium but does not report its initial pH as 7.0 or establish the stated E. coli growth range. (LLM, conf=0.88)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Findingown data

    The difference in lag times between LB broth and fresh coconut water for K. pneumoniae was about 17.0 min and was significant (p < 0.05).

    “the difference of about 17.0 min.was found to be significant, (p < 0.05, Table 2).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Fresh coconut water is favourable for the survival and growth of Escherichia coli and Klebsiella pneumoniae.

    “The study revealed that fresh coconut water is a drink favourable for the survival and growth of Escherichia coli, and Klebsiella pneumoniae.”
    • Also stated in: § 3. Results · plain
      “E. coli survived in the fresh coconut water studied and recorded growth curves that followed the trend expected for a normal bacteria growth curve.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The cell loads of E. coli and K. pneumoniae in fresh coconut water were observed to be high and within infective ranges.

    “Specifically, the cell loads of E. coli and K. pneumoniae in fresh coconut water were observed to be high and within infective ranges.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductnone given

    Optical density measurements were performed in triplicates and each culture was repeated at least once.

    “Measurements of optical density were in triplicates and each culture was repeated at least once.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The significance of possible contributions of nutrient bioavailability, antibacterial proteins, and enzyme products cannot be determined by the results of this study.

    “It must however be stated that the significance of these possible contributions cannot be determined by the results of this study.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationown data

    E. coli adapts better to autoclaved coconut water than to LB broth and much better than to fresh coconut water.

    “The different lag times for the growth of E. coli in LB broth, fresh and autoclaved coconut water (Figure 1 and Table 1), indicates that E. coli adapts better to autoclaved coconut water than it does to LB broth and much better than to fresh coconut water.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationcitation

    Autoclaving may have resulted in either an increase in nutrient bioavailability, reduction or destruction of antibacterial proteins and enzyme products, resulting in the shorter lag time for E. coli in autoclaved coconut water.

    “This may therefore imply that autoclaving may have resulted in either an increase in nutrient bioavailability, reduction or the destruction of these proteins and enzyme products resulting in the shorter lag time for E. coli in it.”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [13] J. G. Fox, “Nutrition: Decontamination of Diets,” In: J. G. Fox, S. W. Barthold, M. T. Davisson, C. E. Newcomer, F. W. Quimby and A. L. Smith, Eds., The Mouse in Biomedical Research, 2nd Edition, Academic Press, Millbrae, 2007, pp. 362-364.

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [14] Joint FAO/IAEA/WHO Expert Committee on the Wholesomeness of Irradiated Food, “Report of the Working Party on Irradiation of Food,” WHO Technical Report Series, No.659, Geneva, 1981.

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [15] source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    High gamma radiation doses resulted in high amounts of free radical generation in fruit juices.

    “The role of persistent free radicals, specifically in gamma irradiation coconut water, is suggested by data that shows that high gamma radiation doses resulted in high amounts of free radical generation in fruit juices.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [21] source

  • May combine two claims.

    Premisecitation

    Polyphenols are toxic with the more oxidised forms being highly inhibitory to the growth of bacteria.

    “Polyphenols have been shown to be toxic with the more oxidised forms being highly inhibitory to the growth of bacteria [19].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [19] M. M. Cowan, “Plant Products as Antimicrobial Agents,” Clinical Microbiology Reviews, Vol. 12, No. 4, 1999, pp. 564-582. source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    Differences in nutritional composition, initial pH, and the extent of pH changes during exponential growth contributed to the differences in growth rate of E. coli.

    “Factors such as differences in nutritional composition, initial pH and the extent of pH changes during the exponential growth period were expected to have contributed to the differences in growth rate.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    The inhibition of growth of both bacteria in stored, gamma irradiated, and autoclaved coconut water could be due to one or a combination of: resultant acidic pH, high increase in free radical concentration, loss of nutrient, or presence of anti-bacterial polyphenols or/and O-quinone.

    “The inhibition of growth of both bacteria in stored, gamma irradiated, and autoclaved coconut water could be due to one or a combination of the following; the resultant acidic pH, high increase in free radical concentration, lost of nutrient or the presence of anti-bacterial polyphenols or/and O-quinone.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Interpretationreasoning

    Autoclaving leads to loss of nutrients, implying a low internal nutrient concentration at dynamic equilibrium and resulting in the slower growth rate in autoclaved coconut water compared to fresh coconut water.

    “As will be discussed later, autoclaving also leads to the loss of nutriaents, implying a low internal nutrient concentration at the point of dynamic nutrient equilibrium resulting in the slower growth rate in autoclaved coconut water compared to that in fresh coconut water.”
    Quote in the paperNot a substantial claim
14 of 14

  • The paper relies on this without support.

    Transferring coconut water into other containers carries a high risk of bacterial contamination.

    “since there is a high risk for bacteria contamination associated with the transfer and storage in other containers.”
    “During this transfer, the water is most likely to be exposed, with a high possibility of contact with pathogenic bacteria.”

  • The paper relies on this without support.

    The burden of foodborne bacterial infections such as E. coli has not been fully investigated or reported for Ghana.

    “The burden of other food borne bacterial infection such as that of E. coli have not yet been fully investigated and/or reported for Ghana.”

  • The paper relies on this without support.

    There are limited reports of the survival and growth of pathogenic bacteria in coconut water.

    “In spite of these seemly opposing potentials of coconut water, there are limited reports of the survival and growth of pathogenic bacteria in coconut water.”

  • The paper relies on this without support.

    The lower limit for survival of E. coli and K. pneumoniae is about pH 4.0.

    “the lower limit for the survival of the two bacteria studied is about 4.0.”

  • The paper relies on this without support.

    The optimal pH for growth of K. pneumoniae is about 6.8.

    “optimal pH for the growth K. pneumonia is about 6.8”

  • The paper relies on this without support.

    E. coli survive between pH 4.5 and 9.0.

    “survive between pH 4.5 and 9.0”
6 of 6

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • E. coli maximum load in fresh coconut water conflicts with Table 1

    Major

    The discussion estimates a stationary-phase load of 5.2-5.6 × 10^8 cfu/mL, but Table 1 reports 2.27 × 10^8 cfu/mL for fresh coconut water. These are substantially different values for the same outcome.

  • Autoclaved coconut water is assigned opposite E. coli growth-rate comparisons

    Major

    The results report a higher E. coli growth rate in autoclaved than in fresh coconut water, while the discussion says the rate was slower in autoclaved coconut water.

2 of 2

Cites

Flagged first, then by citations

Research works printed but not linked: 4

  1. A. Jayalakshmy, C. Arumughan, C. S. Narayanan and A. G. Mathew, “Changes in the Chemical Composition of Coconut Water during Maturation,” Journal of Food Science and Technology, Vol. 23, No. 4, 1986, pp. 203-207.
  2. J. G. Fox, “Nutrition: Decontamination of Diets,” In: J. G. Fox, S. W. Barthold, M. T. Davisson, C. E. Newcomer, F. W. Quimby and A. L. Smith, Eds., The Mouse in Biomedical Research, 2nd Edition, Academic Press, Millbrae, 2007, pp. 362-364.
  3. S. Divakaran, O. Decamp, J. J. Cody and W. G. Dominy, “Studies on Quality Changes in Shrimp Feeds Exposed to Gamma, E-Bem and X-Ray Irradiation,” Journal of Aquaculture in the Tropics, Vol. 17, 2002, pp. 1555-1165.
  4. J. D. Greig, E. C. D. Todd and B. Michaels, “Infective Doses and Pathogen Carriage,” Proceedings of the 2010 Food Safety Education Conference, Atlanta, 23-26 March 2010. http://www.fsis.usda.gov/PDF/Atlanta2010/Slides_FSEC_JGreig_Doses.pdf

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Related

Authors
Awua, A. K., Doe, E. D., & Agyare, R.
Affiliations
Ghana Atomic Energy Commission (GH)
ORCID
Venue
Food and Nutrition Sciences
Publisher
Scientific Research Publishing, Inc.
Published
2012
Volume
03
Issue
08
Pages
1136-1143
ISSN
  • 2157-944X (ISSN-L)
  • 2157-9458
DOI
10.4236/fns.2012.38149
OpenAlex
W1994209960
Cited by
14
References
18
Citations by year
2025: 2 · 2023: 1 · 2022: 4 · 2021: 2 · 2020: 1 · 2019: 1 · 2018: 1 · 2016: 1 · 2014: 1
FWCI
0.18
Type
journal article
Language
en
Open access
Licence
Locations
Food and Nutrition Sciences (publishedVersion, cc-by)
Topics
  • Physical Sciences › Chemistry › Inorganic Chemistry › Coconut Research and Applications
  • Life Sciences › Agricultural and Biological Sciences › Food Science › Food Safety and Hygiene
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Biotechnology › Listeria monocytogenes in Food Safety
Keywords
coconut water, Cocos nucifera, bacterial contamination, Escherichia coli, Klebsiella pneumoniae, bacterial growth, food safety, storage temperature, sterilization, gamma irradiation, time delay, bacterial load, diarrhoeal diseases, consumer health risk

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