Lap-mei (Chinese Preserved Meat) and Food Safety

Lap-mei is a favourite food of many people, distinctive for its colour, aroma and taste.  There are three types of lap-mei available on the local market.  They are preserved Chinese sausages, preserved pork, and preserved ducks.  Recently, media reported that some people tried to prepare their own home-made lap-mei, which has raised food safety concerns.

Some of the curing ingredients used to prepare lap-mei (e.g. salt) have antimicrobial functions while sodium nitrate/nitrite can also inhibit the growth of Clostridium botulinum and its toxin production.  Improper conditions in processing of lap-mei may lead to food deterioration due to bacterial growth, and may affect health after consumption.  However, it is worth noting that Clostridium botulinum may grow in oxygen free and low acid food (such as home-made Chinese sausages) and produce lethal toxin without causing noticeable deterioration in the food.  Application of nitrate/ nitrite in curing should be limited to the amount required to achieve the intended effect only.  Nitrites may react with other substances found in meat forming nitrosamines, compounds that may cause human cancer.  Moreover, ingestion of significant amount of nitrite can cause methaemoglobinaemia, with red blood cells loses its ability to bind oxygen and causes hypoxia in the affected individuals.  The condition is characterised by headache, weakness and breathlessness, and a bluish discolouration of the skin and mucous membranes.  Infants and young children are more susceptible to this condition because their digestive and methaemoglobin reductase systems are still immature.

Members of the public should buy lap-mei from reliable retailers, maintain a balanced diet and avoid excessive consumption of lap-mei (especially for individuals with diabetes, heart disease and high cholesterol).  In addition, infants are highly susceptible to nitrite toxicity and should avoid consuming lap-mei.  The intake of lap-mei among young children should also be restricted.