By Bunmi Ogah-Fasuan (Food Microbiologist)
Fermentation could be described as a process in which microorganisms change the sensory and functional properties of a food to produce an end product that is desirable to the consumer. Although, the end product might not be palatable if the wrong microorganisms contaminate and subsequently ‘ferment’ the food, fermentation id generally regarded as a way to improve the qualities of foods.
Perhaps, what people don’t really know about fermentation is that the process itself is a preservation technique, perhaps one of the earliest preservative methods practiced by man. Although, methods for fermentations were developed by trial and error and from the experiences of many generations, they have now become highly mechanised and technologically-oriented.
There are practically no foods that cannot be fermented given that the appropriate microorganisms are used. From fruits such as grapes, apple and orange, to grains such as wheat, barley and rice, and to finally meats, fermentation has been carried out on every eaten food, leading to production of many fermented foods which we have around nowadays.
Having been displaced as the most used preservative method by more recent and advanced preservative methods, its uses have declined in most advanced countries. However, it remains the primary method for prolonging the shelf-lives of most food products, and remains a very appropriate method for use in developing countries and rural communities with limited facilities. Also, it is the major alternative method to chemical preservation, as fermentation relatively doesn’t alter the chemical composition of foods, but attempt to eliminate/reduce spoilage microorganisms or controlling their growth and the overall composition of the microflora.
Fermentation makes use of three effective principles: (i) minimising the level of microbial contamination onto the food, particularly from “high-risk” sources (ii) inhibiting the growth of the contaminating microflora, and (iii) killing the contaminating microorganisms. The basis for preservation by fermentation is the ability of some microorganisms to effectively change their environment, and make them inhibitory to other microbes. Thus, “fermentation improves the safety of foods by decreasing the risks of pathogens and toxins achieving the infective or toxigenic level, and extends the shelf life by inhibiting the growth of spoilage agents, which cause the sensory changes that make the food unacceptable to the consumer.”
Although fermentation is essentially a preservative method, the general acceptability of fermented foods by consumers is based on the change in their sensory properties caused by the biochemical activities of the fermenting microorganisms. This leads to a change in the taste, smell and appearance of these foods. However, the benefits of fermented foods are not only found in the improvement of the sensory properties; there are many other benefits.
Fermentation has low energy demands and can often be carried out without sophisticated and mechanised plants. It is based on simple techniques, which means that the procedures can often be carried out at homes. Also, many studies have shown that consumers regard fermented food products as healthy and natural, increasing consumer demands and their profitability.
Also, there are notable increase in the safety, retail and nutritional values, digestibility and shelf-life. Most fermented foods are considered safe because of the elimination or inhibition of growth of dangerous microbes, and it has been established that the nutritional contents of fermented foods are higher than non-fermented foods because of the biochemical conversion of the food compositions.
Coupled with the above is increase in the suitability of those fermented foods for subsequent processing. Coupled with these is the reduction in toxicity, production cost, cooking time, equipment needed and antinutritional factors. All these make ferme