12 January - 20 June 2016

An effective natural flavonoid-based food preservative

A study conducted by researchers from Singapore’s Nanyang Technological University, published in the journal Food Chemistry, has recently demonstrated the ability of a natural plant-based food preservative.

Most modern food preservatives are synthetic chemicals and some recent research has focused on the health risks concerned with consumption of these chemicals. This has fuelled interest in natural sources of food preservatives from plants and essential oils amongst other. A study conducted by researchers from Singapore’s Nanyang Technological University, published in the journal Food Chemistry, has recently demonstrated the ability of a natural plant-based food preservative.

Flavonoids are phenolic compounds found as secondary metabolites in plants and are responsible for vivid colours of flowering plants and also produced as a defence mechanism to environmental changes. Much has been written about their health benefits including their anti-inflammatory, anticancer and antimicrobial properties. While some flavonoids have been shown to possess antimicrobial properties, the extraction from plants in large quantities involves high cost while chemical synthesis is similarly expensive and has additional disadvantages.

Previously, the authors of the current study have developed a technique to produce flavonoids by metabolically engineering a strain of baker’s yeast called Saccharomyces cerevisiae (N2). They note that this technique has several advantages including that it enables easy separation of the compounds produced from the culture when compared to extraction direct from plants and is not seasonally affected, as may be the case for specific plants used for extraction

The current study by Chen et al. sought to investigate the antimicrobial and antioxidant effects of the phenolic compounds extracted from naringenin-producing N2 bio-fermentation.  As well as naringenin, these included phloretic acid, homogentisic acid and phenylacetaldehyde. Chen et al. also sought to compare the effects of this mixture to those exhibited by the pure phenolic compounds identified in the mixture.

Chen et al. assessed the antimicrobial properties of the N2-produced compounds using a variety of techniques including agar disc diffusion assay against E. coli ATOC 25922 and Staphylococcus aureus ATC 29213 and DMPD+ chemiluminescence assay as well as testing against food products. The team discovered in that in tests on meat and fruit juices at room temperature, the N2-produced compounds kept its samples fresh for two days compared to 6 hours using artificial preservatives.

Prof Chen is quoted in a press release as saying that “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.” Chen added that "This may open new doors in food preservation technologies, providing a low-cost solution for industries, which will in turn encourage a sustainable food production system that can produce healthier food that stay fresh longer”.

In conclusion, the study states that the compounds extracted from the engineered Saccharomyces cerevisiae strain showed “good, broad-spectrum antibacterial activity surpassing all other pure flavonoids and phenolics tested in this study, bar phenylacetaldehyde” The compound also showed strong antioxidant activity.  They also note that that the enhanced effect of the N2-produced phenolic compounds over the pure compounds may be due to  “unknown synergistic effects” between the different phenolics produced and that future work should carry out combinational testing to isolate and identify such synergies as well as conducting antimicrobial assays against additional common food pathogens such as Campylobacter sp., Salmonella sp. and Listeria monocytogenes.

RSSL is happy to discuss with clients the analysis of phenolic components.  To find out more please contact Customer Services telephone 0118 918 4076 or e-mail enquiries@rssl.com

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