Artificial preservatives are used to make food last longer. However, it comes at a cost. Preservatives used to keep meat fresh have been linked to thyroid troubles and cancers. Scientists from the Nanyang Technological University in Singapore have discovered how to create a plant-based preservative that is actually more effective than artificial preservatives.

Flavonoids are phytonutrients that are found in almost all fruits and vegetables. They give produce, such as strawberries, kale, and grapes, their bright colors. Otherwise, they defend plants against pathogens, pests, and environmental stress. They have already been known to be antimicrobial, but have not been used in food production because they would require another cost and time intensive processing step to defend against bacteria.

The breakthrough here is that the researchers found an easier way to extract flavonoids by implanting the flavonoid-producing mechanism from plants into baker’s yeast. The yeast then produced the flavonoids. It is a similar procedure to manufacturing vaccines using yeast. This new process yields flavonoids that have greater antimicrobial properties than samples taken directly from plants and the added bonus of antioxidant properties.

Preservatives are added to fruit juices to make them stay fresh longer. Image credits: Pixnio.

“Antimicrobial and antioxidant properties are key elements in food preservation. Flavonoids extracted directly from plants need to be further processed to be antimicrobial whereas our flavonoids produced from yeast do not require this. Secondly, there have been no reports on antioxidant properties in flavonoids while our yeast-based flavonoids naturally come with it,” said Professor William Chen, Director of NTU’s Food Science & Technology programme.

These flavonoid-based preservatives were tested on meat and fruit juice samples. The food samples were treated with the new natural preservative and artificial preservatives, and left at room temperature. The food treated with the flavonoid-based preservative stayed fresh for two days, while the food treated with artificial preservatives only lasted about six hours before being colonized by bacteria.

“This organic food preservative is derived from plants and produced from food grade microbes, which means that it is 100 percent natural. It is also more effective than artificial preservatives and does not require any further processing to keep food fresh,” said Prof Chen.

The researchers are already developing their technique to be used in the food industry. Hopefully we will be seeing these all-natural preservatives in packaged food in the near future.

Journal reference: Kuan Rei Ng, Xiaomei Lyu, Rita Mark, Wei Ning Chen. Antimicrobial and antioxidant activities of phenolic metabolites from flavonoid-producing yeast: Potential as natural food preservatives. Food Chemistry, 2019; 270: 123 DOI: 10.1016/j.foodchem.2018.07.077.