Plants in the wild do not go mouldy, and yet they are in an environment that predisposes them to suffer from the infestation of all type of spoilage organisms. Yeasts, moulds and bacteria abound in the soil, all working to breakdown dead plant material and provide fresh humus for those plants living in the soil. Living plants resist the natural forces of disintegration.

It is concluded, that the chemical constituents within each plant clearly differ in composition. Furthermore, that there is a chemical or group of chemicals present in the plant that is capable of killing micro-organisms. This chemical composition varies according to whether the plant is alive or dead, and in certain/most plants will vary according to season. In many cases, when these substances are extracted, it is found that the extracts are capable not only of resisting certain spoilage organisms, but in some cases can actively act to destroy them.

Specific organisms are identified as being of particular interest. These include, for example, Candida albicans, Pseudomonas aeruginosa, Escherichia coli, Aspergillus niger and Staphylococcus aureus.

Take the garlic (Allium sativum), for example. There are numerous benefits of garlic, including yeast infections (by Candida albicans) of the skin or mucous membranes. The bulb contains 0.1-0.4% of a volatile oil composed of alliin or S-methyl L-cystein sulphoxide. Allicin is the major odour principle that is produced by the enzymatic action of alliinase into alliin. The bulb contains about 17% of proteins, mineral matters and vitamins (B1, B2, PP, C). However, the main components of garlic are fructosans which account for up to 75% of the dried weight. The smell and the bacteriostatic and antifungal properties are due to the sulphur containing compounds. They are particularly efficient against dermatophytis and pathogenic yeasts (Candida).

The number of plants and of active substances that we could use as examples and with preservatives properties is very high. Some examples of plants could be: Eucalyptus globulus, Allium sativum, Echinacea angustifolia, Citrus paradisi, Cumin cyminum, Berberis vulgaris, Rosmarinus officinalis, Calendula officinalis,… For example Rosemary extract has been used for hundreds of years. It also gives food a nice aroma and flavor.

Natural preservatives are considered safer by many because they have always existed in nature and our immune systems are used to them. Most of the preservatives that come from a plant source are safe for humans. The main disagreement when it comes down to the use of natural preservatives is that sometimes (some substances) they are not powerful enough. This may be true depending on the substance but, it does not mean that because of this more chemical or synthetic preservatives need to be used.