In 2006, the Centre for Food Safety (CFS) received a number of complaints from the public regarding the presence of larvae inside bottled soy sauce. Investigation revealed that the larvae were mainly larvae of flies, a minority of the samples were also infested with adult flies.
The odour of fermented food (including soy sauce) is attractive to flies. If the lid of a bottled soy sauce is not properly covered, flies have the opportunity to come into contact with the soy sauce and even lay eggs (some fly species lay larvae direct) on it.
By adopting modern production facilities and techniques, scrupulous production process and emphasizing personal and environmental hygiene, the presence of larvae in soy sauce can be prevented.
In 2006, the CFS did not receive any complaints regarding presence of larvae in unopened bottled soy sauce.
To prevent presence of larvae in bottled soy sauce, the CFS wrote letters to manufacturers and importers in October 2006, advising them to improve design of lids of soy sauce bottles so as to allow the lids to close tight after use and more user friendly, and to advise the consumers, on product labels, to close the lid tightly and clean the bottle thoroughly after use and to store the product properly.
Advice to soy sauce manufacturers
- Improve production facilities and techniques, adopt scrupulous production process and emphasize personal and environmental hygiene.
- Conduct pest survey regularly. Whenever pests (including flies) are detected, control actions should be taken promptly to rectify the situation.
- Improve design of the lids of soy sauce bottles so as to allow them to close tight after use.
- Advise the consumers, on product labels, to close the lid tightly and clean the bottle thoroughly after use and to store the product properly.
Advice to the catering trade and the public
- Close the lid tightly and clean the soy sauce bottle thoroughly after use.
- Store opened soy sauce properly.
Centre for Food Safety
Food and Environmental Hygiene Department
February 2007
Q & A on Prevention of Fly Breeding in Bottled Soy Sauce
Q. Why are larvae found in bottled soy sauce?
A. The odour of fermented food (including soy sauce) is attractive to flies. If the lid of a bottled soy sauce is not properly covered, flies have the opportunity to come into contact with the soy sauce and even lay eggs (some fly species lay larvae direct) on it.
By adopting modern production facilities and techniques, scrupulous production process and emphasizing personal and environmental hygiene, the presence of larvae in soy sauce can be prevented. In 2006, the CFS did not receive any complaints regarding presence of larvae in unopened bottled soy sauce.
The consumers can prevent fly breeding in bottled soy sauce simply by closing the lid tightly, cleaning the bottle thoroughly after use, and storing the product properly. Furthermore, the key to fly control is environmental sanitation. Members of the public are advised to maintain good environmental sanitation.