How raw pork from Vietnam can help us keep food fresh, naturally

Vietnamese fermented pork appetizer, Nem Chua. Credit: RMIT University

Fermented meat helps researchers develop a safe, all-natural preservative.

A traditional Vietnamese meat snack could be key to developing a safe and natural food preservative that solves the dual global problems of food waste and foodborne illness.

  • A compound that kills bacteria found in Nem Chua, a fermented pork snack
  • Toxic to bacteria but safe for humans, it is a natural alternative to artificial food preservatives
  • Research shows ideal conditions for growth that can potentially make killer bacteria on an industrial scale

A fermented pork appetizer, Nem Chua, is eaten raw but does not cause food poisoning when properly prepared.

This is because the friendly bacteria that grow in fermented meat produce a special compound that kills more dangerous bacteria.

Now researchers from RMIT University in Melbourne, Australia, have shown how this natural compound that kills bacteria can be used to keep food fresh longer.

Food waste is a global problem that costs about $ 680 billion annually in industrialized countries, consumes nearly a quarter of the water used in agriculture, and produces 8% of global greenhouse gas emissions.

Foodborne illnesses, such as listeria or salmonella, affect millions every year and can be life-threatening for pregnant women, the elderly and people with reduced immunity.

Listeria bacteria

Listeria bacteria (green) that die after exposure to plantacycline B21AG. Bumps, visible on many cells, are the contents of cells that begin to leak. Author: Dr. Elvina Parlindungan

Research Fellow Professor Oliver Jones said changes in consumer habits have led to an increase in demand for natural alternatives to artificial food preservatives.

“Scientists have known about these bacteria-destroying compounds for years, but the challenge is to produce them in large enough quantities for use in the food industry,” said Jones, deputy dean of RMIT’s biological sciences and food technology.

“Nem Chua’s compound is colorless, odorless, tasteless and very elastic.

“Thanks to this new study, we have identified the right growth conditions that will allow us to produce it in large quantities, potentially on an industrial scale.

“With further development, we hope that this can be an effective, safe and natural solution for both food waste and food diseases.”

Weapons to kill bacteria

A team of RMIT researchers was inspired to investigate Nem Chua for its potential antibacterial properties after traveling to Vietnam and observing people eating raw meat without getting sick despite the hot and humid climate.

A team led by Professor Andrew Smith (now at Griffith University) and Dr. Bee May has discovered a new type of bactericidal compound in Nem Chua.

Plantocycline B21AG is a group of compounds known as bactericins produced by bacteria to kill competing strains of bacteria.

Listeria Plantacyclin B21AG

Left: Listeria bacteria, alive and with intact cell membranes. Right: The same bacteria after exposure to Plantacyclin B21AG, dead and with destroyed cell membranes. Author: Dr. Elvina Parlindungan

Bactericins form holes in the membranes of target bacteria. This leads to leakage of cell contents, which effectively kills bacteria.

The problem is that most bacteria only work against one or two types of bacteria, and they are not very stable in different environmental conditions.

Only one – Nisin, which came on the market in the 1960s – is currently licensed for use as a food preservative, the market is estimated to cost more than $ 513 million in 2020, but this compound is temperature sensitive and pH, which limits its use.

Tough and effective

The compound obtained from Nem Chua is more reliable than Nisin, and effective against a wide range of bacteria even after exposure to a number of environments typical of the food industry.

It can survive when heated to 90C for 20 minutes and remains stable at high and low pH levels.

The compound can also destroy a number of pathogens commonly found in food, including potentially life-threatening listeria that can survive cooling and even freezing.

Lead researcher Dr Elvina Parlindungan, who completed a new study as part of her doctoral research at RMIT, is now a post-graduate student at APC Microbiome, part of Cork University College in Ireland.

“Using bactericins as food preservatives effectively means we are turning our own toxic weapons against bacteria – using nature’s smart solutions to solve our big problems,” Parlindungan said.

“In the future, these compounds may also be useful as antibiotics in human medicine.”

Researchers from the RMIT School of Science have begun experimenting with methods to further purify the compound and plan to incorporate it into test foods.

Help: “Factors affecting bactericin’s growth and production Lactiplantibacillus plantarum B21 ″, Elvina Parlindungan, Caitali Dekivadi and Oliver A.H. Jones, May 18, 2021, Biochemistry of processes.
DOI: 10.1016 / j.procbio.2021.05.009

The team is committed to collaborating with potential industry partners to further develop the technology.

This work was supported by a doctorate from the Indonesian Education Foundation (LPDP), which is part of the Ministry of Finance of the Republic of Indonesia, awarded to Parlindungan. How raw pork from Vietnam can help us keep food fresh, naturally

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