Natural Plant-based Food Preservative

The shelf life of the fruits and vegetables is limited. Towards the value addition, the juices, sauce, pickles etc need food preservatives  Extending the shelf life of these value added  fruits and vegetables, used  the certain preservatives . These artificial preservatives are manmade and some time the efficacy of these preservatives is questionable due to side effects.

Recently the researchers at  Nanyang Technological University, Singapore (NTU Singapore) discovered a plant-based food preservative. The newly discovered natural plant based food preservative is more effective than artificial preservatives.

In the early days, some of the natural preservatives, such as citrus fruit juices, salt, sugar and vinegar, were traditionally used to preserve food. With the evolutionary changes, the food industry has been looking at using plants and their extracts as potential means to food preservation. Here are 5 potential clean-label, plant-derived alternatives to some chemical preservatives. 

During food manufacturing, there are many chemical and microbial interactions that take place within the food system. These interactions include temperature, water activity, pH, competitive flora, preservatives, and Maillard reaction, amongst others. The overall aim is to effectively preserve food products and improve their shelf life. Therefore, by using an intelligent mix of additives, it is possible to improve not only the microbial stability and safety, but also the sensory and nutritional quality of a food product.

Artificial food preservatives revolutionized the food industry to ensure a longer shelf-life of food products. This has facilitated the widespread distribution and mass production of food as well as opened up new markets.

Beyond shelf-life extension, preservatives have additional roles in food production. For example, processed and refined food products require the application of preservatives to inhibit natural ageing and discoloration. In addition, some preservatives also serve rheological purposes; they act as emulsifiers, stabilizers and thickeners to give foods their desirable texture and consistency.

From a health perspective, artificial preservatives have been criticized for their various side effects, including gut diseases and obesity.  However, replacement of preservatives is far from a simple process. There are numerous factors to consider in the processing of shelf-stable food products.

In tests carried out on meat and fruit juice samples, the organic preservative kept its samples fresh for two days without refrigeration, compared to commercial-grade artificial food preservatives.

The experiment was conducted at room temperature (about 23 degrees Celsius) where the other food samples with artificial preservatives succumbed to bacteria contamination within six hours.

The organic preservative comprises a naturally-occurring substance known as ‘flavonoids’, a diverse group of phytonutrients found in almost all fruits and vegetables. The flavonoids created by NTU scientists have strong anti-microbial and anti-oxidant properties; two key traits of preservatives that inhibit bacterial growth and keep food fresher for longer.

The NTU research team was led by Professor William Chen, Director of NTU’s Food Science & Technology programme. The team is already in talks with multinational companies to further develop the new food preservative. Prof Chen said, “This organic food preservative is derived from plants and produced from food grade microbes, which means that it is 100 per cent natural. It is also more effective than artificial preservatives and does not require any further processing to keep food fresh.

In food preservation technologies,it is  a low-cost solution for industries, which could in turn encourage a sustainable food production system that produces healthier food that stays fresh longer.

Flavonoids are naturally occurring chemicals in plants which are responsible for defending plants against pathogens, herbivores, pests, and even environmental stress such as strong ultraviolet rays from prolonged hours of sunshine.

Found in almost all fruits and vegetables, it is responsible for inducing vivid colours in them. These include onions, tea, strawberries, kale, and grapes.

Though flavonoids’ anti-microbial potential have been reported, they have not been used as a food preservative because they require further processing before they can mitigate bacteria. This is known as ‘prenylation’ – a process involving the addition of hydrophobic molecules onto a protein to facilitate cell attachment – which is not cost-effective or sustainable.

NTU researchers have not only found a way to grow flavonoids with high anti-microbial and anti-oxidant properties but also in a natural and sustainable manner. They achieved this by implanting the flavonoid-producing mechanism from plants into baker’s yeast (a species known as Saccharomyces cerevisiae).

Similar to how vaccines are manufactured using yeast, the researchers found that the yeast produced flavonoids with high anti-microbial properties, which are not even present in pure flavonoid samples extracted directly from plants.

Prof Chen further added, “Anti-microbial and anti-oxidant properties are key elements in food preservation. Flavonoids extracted directly from plants need to be further processed to be anti-microbial whereas our flavonoids produced from yeast do not require this. Secondly, there have been no reports on anti-oxidant properties in flavonoids while our yeast-based flavonoids naturally come with it.

Flavonoids are important natural food supplements with vitamins, but also used as food additives, without causing harm to the human system. This is unlike currently available artificial preservatives used in most processed foods such as aspartame and nitrates, which may cause cancer among other adverse health effects.

The NTU research team aims to further develop their findings with the food industry and enhance its efficacy and safety so that it can be used in all packaged food products.