An overview of the potential use of plant-derived antimicrobial compounds as natural preservative against spoilage micro-organisms in food products: A review

Abstract

In recent years, consumers have started paying more attention to the ingredients in their food. Many people now prefer products that are less processed and made with recognizable ingredients. Due to this, the food industry has been put under pressure to explore natural alternatives, which is challenging regarding the preservation of these products. During food production, harmful microorganisms must be controlled since these may cause disease when we are exposed to them. There is also another group of microorganisms which is usually not harmful, however these may negatively affect the quality of a food product. To prevent growth of these microorganisms, preservatives are added to the product. Preservatives slow down the growth of yeasts and moulds and therefore improve the shelf life – period from production to expiry date – without changing the smell or taste of a product. Currently, most products contain synthetic preservatives, which are widely used due to their low cost and broad availability. However, consumers are concerned about possible health effects after long-term consumption of these preservatives. Due to these concerns, food industry is seeking natural alternatives. A promising group of natural preservatives originates from plants. Plants naturally make substances with antimicrobial and antioxidant activity as defence mechanism against environmental factors and other organisms. These bioactive substances are extracted from plants in the form of essential oils or extracts, which may be added to a food product. Via this way they are able to control growth of spoilage microorganisms and improve the preservation of the product. Research has shown that many plant sources such as cinnamon, clove, dill, garlic, nutmeg, oregano and thyme contain these bioactive substances. Studies have demonstrated this by testing in the lab, as well as in food products. Testing these substances in food is especially important, since these extracts are often strong in flavor and smell, which may negatively affect the product. For this reason, more research is needed to find more plant sources which may be used as food preservatives, both effective against microorganisms and acceptable in taste. There is strong potential in this group of plant sources, which has also been shown in many published patents. For example, a mixture of liquorice, aloe, honeysuckle and dandelion when added to fresh vermicelli, increases the preservation for 2-3 months. Studies and patents show evidence that plant-derived preservatives may be considered as potential natural alternatives to the current used synthetic preservatives.