Microbiological and Chemical Quality of Mineral Waters - 1998

October December 1998

Report prepared by Geoff Millard and Simon Christen

OBJECTIVE

To assess the compliance of Mineral and Packaged water sold in the ACT to the Australia New Zealand Food Authority (ANZFA) Food Standards Code.

BACKGROUND

Mineral and packaged waters are widely available in the ACT. The ANZFA Food Standards Code (FSC) has standards for these products and this survey was conducted to determine their compliance to those standards

STANDARDS

Definitions

  • Mineral water is defined in the Food Standards Code (FSC) as "ground water obtained from subterranean water-bearing strata that, in its natural state, contains soluble matter".
  • Carbonated water means water that has been impregnated with carbon dioxide under pressure;
  • Mineralised water means water, whether or not impregnated with carbon dioxide under pressure, to which mineral salts have been added;
  • Soda water means:

(a) carbonated water; or

(b) carbonated water to which carbonate or bicarbonate salts of sodium or potassium have been added.

  • Soft drink is a product prepared from water, mineral water or mineralised water, and flavourings.
  • packaged water means water for human consumption, other than mineral water, which has been packaged for sale.

Microbiological standards

Mineral Waters

When tested by the methodology described in AS 1766.4.5 the product should be free of coliforms in 250mL.

When tested by the methodology described in AS 4276 part 13 the product should be free of Pseudomonas aeruginosa in 250mL.

Packaged Waters

When tested by the methodology described in AS 1766.4.1.2 the product should have a Standard Plate Count (SPC) not exceeding 100 microorganisms per millilitre.

When tested by the methodology described in AS 1766.4.5, the product should be free of coliforms in 250mL.

When tested by the methodology described in AS 4276 part 13 the product should be free of Pseudomonas aeruginosa in 250mL.

Chemical Standards

The FSC has an extensive list of maximum permitted concentrations for a range of ions for mineral water, mineralised water, soda water or carbonated water. Packaged water may contain not more than 1.5 mg/l of fluoride.

Labelling

Mineral water is required to be labelled with a typical analysis of mineral constituents in descending order of concentration (mg/L) and can include: arsenic, barium, borate, cadmium, carbonate, chromium, copper, free chlorine, cyanide, fluoride, lead, manganese, mercury, nitrate, nitrite, potassium, selenium, sodium, sulphide and zinc.

SURVEY

Between the beginning of October and beginning of December 1998 seventy-two samples representing forty-seven different brands of mineral/packaged water were collected. These seventy-two samples consisted of sixty-five mineral waters and seven packaged waters. The samples were purchased from twenty different establishments around the ACT.

RESULTS

Microbiological

Standard Plate Count (SPC)

Only packaged water has a requirement to meet an SPC standard. Of the seven packaged waters tested, six failed the standard. Those failing the SPC Standard of <100 cfu/mL. had counts between 600 and 14,000 colony forming units (cfu) per millilitre (mL).

Graph 1 Distribution of SPCs in Package waters

Graph 1

 

Graph 1 Distribution of SPCs in Package waters

Coliforms

Coliforms were not detected in any of the seventy-two waters tested.

Pseudomonas aeruginosa

Pseudomonas aeruginosa was not detected in any of the seventy-two waters tested.

Chemical Analysis

Minerals tested on the samples were confined to cadmium, copper, lead, magnesium, zinc, potassium, sodium, cyanide, carbonate and fluoride.

Of the minerals tested, and where a limit was imposed by the Food Standard Code, none of the samples were found to exceed their limits.

Cadmium

All samples had results < 0.001 mg/L. The permitted level is 0.005 mg/L.

Copper

All samples had results < 0.036 mg/L. The permitted level is 1.0 mg/L.

Lead

All samples had results < 0.04 mg/L. The permitted limit is 0.05 mg/L.

Magnesium

 

Magnesium in Mineral Water Graph

There is no set limit for magnesium.

Zinc

 

Zinc in Minerial Water Graph

The permitted level for zinc is 5000 ug/L.

Carbonate ion

The carbonate values ranged from < 10mg/L to > 1000 mg/L. There is no limit set for carbonate.

Potassium

 

Potassium in mineral water graph

There is no set limit for potassium. There was insignificant difference between the labelled concentration and measured value.

Fluoride

 

Fluoride in minerial water graph

All samples tested had < 1.1 mg/L and the set limit is 1.5 mg/L.

Cyanide

 

Cyanide in mineral water graph

All samples tested < 0.03 mg/L and the limit is 0.1 mg/L.

DISCUSSION

Chemical

All mineral waters tested complied with the Food Standard Code for content and labelling requirements

Microbiological

None of the seven packaged waters tested contained either of the pathogens tested for, but six out of the seven did exceed the SPC standard. The exceedences were not great and were unlikely to represent a public health concern. All of 65 mineral waters tested, complied fully with the FSC microbiological standards.

CONCLUSION

The survey results indicate that:

Chemical analysis should not be necessary in future unless contamination is suspected.

  • The survey results indicate that the microbiological quality of mineral waters sold in the ACT complied with the standards. Six of the seven packaged waters however did not comply with the SPC standard. Possible causes of the unacceptable SPC results for packaged waters could be either the packaged waters did not meet the criterion prior to packaging or "regrowth" of sub-lethally injured cells, during storage, after treating with a disinfectant.

  • The recently gazetted Joint Australia New Zealand Food Standards Code, Standard 1.6.1, Microbiological Limits for Food, 20th December 2000 specifies only one microbial criteria for Mineral and Packaged Waters i.e. E. coli with a permitted limit of <1 cfu per 100mL. The criteria for SPC, Coliforms, and Pseudomonas aeruginosa have been dropped.

  • The amendments to the FSC means that these results are not a significant Public Health concern.

BIBLIOGRAPHY

Australia and New Zealand Food Authority, Food Standards Code, incorporating amendments up to and including Amendment 38, April 1998.

Australia and New Zealand Food Authority, variation to Food Standards Code, Amendment 53 December 20 2000.

Food Act 1992 (ACT), reprinted as at 31 January 1996.

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Microbiological and Chemical Quality