|Nem chua (fermented pork rolls) – PHOTO: SGT WEEKLY
Nem chua is eaten raw but does not cause food poisoning when prepared correctly. This is because friendly bacteria that thrive in the fermented meat make a special compound that kills the more dangerous bacteria.
Researchers at RMIT University have shown how this natural bacteria-killing compound could be used to keep food fresh for longer.
Co-lead researcher Professor Oliver Jones, Associate Dean of Biosciences and Food Technology at RMIT, said changes in consumer habits have led to a greater demand for natural alternatives to artificial food preservatives.
“Scientists have known about these bacteria-killing compounds for many years but the challenge is to produce them in large enough quantities to be used by the food industry,” said Professor Jones.
“The nem chua compound is colorless, odorless, tasteless and very resilient. Through this new research, we have identified the right growth conditions that would enable us to make it in large amounts, potentially at an industrial scale. With further development, we hope this could be an effective, safe and all-natural solution for both food waste and food-borne diseases,” Professor Jones added.
The team of RMIT researchers was inspired to investigate nem chua for its potential antibacterial properties after observing Vietnamese people eating it without getting sick, despite the hot and humid climate.
The team, led by Professor Andrew Smith (now at Griffith University) and Dr Bee May, discovered a new type of bacteria-killing compound in nem chua. Plantacyclin B21AG is one of a group of compounds known as bacteriocins, which are produced by bacteria to destroy rival bacterial strains.
Bacteriocins form holes in the membranes of target bacteria, which causes the contents of the cell to leak out, effectively killing the bacteria.
The problem is most bacteriocins only work against one or two types of bacteria and are not very stable in different environmental conditions.
Only one, Nisin, which came to the market in the 1960s, is currently licensed for use as a food preservative but this compound is temperature and pH sensitive, limiting its use.
The nem chua-derived compound is more robust than Nisin and is effective against a wide range of bacteria even after exposure to a range of environments typical in food processing. It can survive being heated to 90 degrees Celsius for 20 minutes and remains stable across high and low pH levels.
“Using bacteriocins as food preservatives effectively means we are turning the bacteria’s own toxic weapons against them, harnessing nature’s smart solutions to tackle our big challenges. In the future, these compounds might also be useful as an antibiotic in human medicine,” said co-lead researcher Dr Elvina Parlindungan.
Researchers at RMIT’s School of Science have begun experimenting with methods to further purify the compound and are planning to incorporate it into test food products.