QUESTION CORNER
Quality of honey
PHOTO: A.M. FARUQUI
Why doesn’t honey get spoilt?
Chetan K. Gopal
Chikmangalur, Karnataka
The primary reason for long shelf life of honey is the low ‘available water’ content. The water activity (relative availability of water in a substance) of honey is only about 0.6 and growth of fungi and bacteria requires a minimum water activity of about 0.7 and 0.9 respectively.
Therefore honey does not support the growth of microbes which would spoil it. Honey is a thick solution (about 83 per cent solid matter) of primarily fructose and glucose, two simple sugars. Honey bees collect nectar from flowers and the sucrose in the nectar is partially digested by the bees to yield fructose and glucose.
Nectar is very dilute compared to honey and contains natural yeasts and some micro organisms commonly present in the environment.
In the beehive, water from the nectar gets evaporated (apparently due to air flow created by the beating of honeybees’ wings) leading to low water content in honey.
While the low water content of honey does not support growth of micro-organisms or fermentation, some spores could stay dormant in honey for a long time.
For this reason, it is not advisable to give honey to young infants (under 1 year old) especially to avoid the risk of Clostridium botulinum infection.
Senthil Subramanian
Donald Danforth Plant Science Center,
St. Louis, U.S.
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