Dear Editor,
Indre Kisonas’ June 28 article “Old Wives Tales and Remedies – Fact or Fiction?” says “crushed garlic cloves can also be put into a jar with natural honey and left to ferment for a few weeks to months” before being ingested.
I wish to provide a warning about this method of garlic preservation, due to the risk of botulism.
The CSIRO provides the following advice on the preservation of foods and herbs:
“Foods with a pH below 4.6 do not in general support the growth of food poisoning bacteria, including C. botulinum. The necessary pH adjustment for these products can be achieved only by adding acid to the vegetable material. Vinegar, which is a solution of acetic acid, is the usual choice.
“Attempts to preserve these products without acidification seem to be based on two false assumptions. The first of these is that the addition of oil has a preservative effect. This is incorrect. The only function of the oil is to prevent oxidation from the air in the container which can lead to discolouration of some foods. By excluding air from the surface of the vegetable, it establishes anaerobic conditions which actually favour the growth of some types of bacteria. Unfortunately, C. botulinum is one of these bacteria.
“The other incorrect assumption which is often made is that some herbs and spices, and especially garlic, have significant anti-microbial properties. The preservative effect of these materials including garlic is slight and inconsistent as the botulism incidents in Canada and the United States prove.
“It is therefore essential that sufficient acid is added to the vegetable before oil is poured on and time is allowed (say overnight) for the pH of the vegetable to equilibrate to below pH 4.6 so that any C. botulinum or other potentially dangerous bacteria cannot grow. Vinegar prepared for domestic use contains 4 per cent acetic acid. Vinegar should be added to the vegetable component of these preserves before any oil is added so that the ratio of vegetable to vinegar by weight is not greater than three to one. For example, to make 400 grams of preserved garlic, one would mix 300 grams of garlic with 100 grams of vinegar. The resulting mixture will then contain approximately one per cent acetic acid which would ensure a final pH below 4.6. This will not guarantee that the products will not spoil if not kept properly refrigerated, but it will ensure they do not become toxic.”
While it is said that honey is acidic and its pH ranges from 3.4 to 6.1 for different types of honey (with an average pH of 3.9) this does not guarantee a pH below 4.6 so, so unless the pH of a particular honey can be tested we should avoid use of honey as suggested by the author, unless it is used in a similar way to oil (after vinegar use) described previously.
Of note is that honey can actually carry the botulism bacteria and the Royal Children’s Hospital advises honey should consequently be avoided in children less than 12 months old.
Dr Greg Malcher, retired GP
Hepburn
Response:
Thank you, Dr Malcher, for being vigilant and noting that botulism can occur in some honey with higher pH. Home preservers should take care to measure honey pH when preserving with it.
Indre Kisonas
Editor’s note: The original article has been edited to delete the suggestion that garlic can be preserved in honey.
