Testing honey for antimicrobial properties

Food scientists at The University of Queensland (UQ) have discovered a new, low-cost way of accurately predicting the antimicrobial properties of honey.

UQ Queensland Alliance for Agriculture and Food Innovation (QAAFI) researcher Dr Yasmina Sultanbawa said natural compounds in honeys were known to inhibit bacterial infections such as Staphylococcus and E.coli.

Dr Sultanbawa said honeys derived from a family of Australian and New Zealand plants known as Leptospermum were of particular interest to scientists, because they often contain compounds that inhibit microbes.

However, she said previous methods of testing had tended to be limited in scope, requiring relatively complex and expensive testing procedures.

The researchers tested a range of honey samples for antimicrobial activity and found different levels of antimicrobial properties.The selection included heath (Banksia ericifolia), yellow box (Eucalyptus mellidora), iron bark (Eucalyptus crebra), juniper (Leptospermum juniperinum) and jelly bush (L. polygalifolium) honeys, which consistently register the highest concentration of antimicrobial properties.

Dr Sultanbawa’s team found that exposing honey to light in the mid-infrared range could be used to accurately predict the presence and quantity of methylglyoxal, a key antimicrobial compound in honey.

The research is published in the article Infrared spectroscopy as a rapid tool to detect methylglyoxal and antibacterial activity in Australian honeys in the Food Chemistry journal.