Cultures in the food and feed industry

For centuries microbial organisms have been part of nature, assuring a number of naturally occurring fermentation processes. Today micro-organisms are used in industrial food and feed production and the interest of the industry is safeguarded through the European Food and Feed Cultures Association (EFFCA).

Historical overview

Micro-organisms have always been part of the environment and for centuries they have been responsible for a wide range of fermentation processes, hereby assuring the balance in nature. Also in the food manufacture micro-organisms have been known for centuries. In ancient times every family, community or small manufacturer kept their own mixture of micro organisms to make bread, beer, wine or vinegar, yoghurt, cheese, fermented fish, meat, vegetables and even silage.

Micro-organisms have many useful applications such as:

· Preservation of a basic product: Where milk cannot be kept, it's nutritional components can be safeguarded under the form of cheese,
· Creation of new products: beer comes from an association of micro-organisms with an aqueous solution of cereals,
· Modification of properties: the wide variety of cheeses is possible thanks to the fermentation obtained by a variety of micro-organisms.

For centuries human observation and intelligence allowed empirical selection. However, already in 1837, researchers detected that the yeast detected during the alcoholic fermentation was responsible for the transformation of sugar into alcohol. From 1857 to 1876, when Pasteur and his colleagues began to explain the accidents observed in the production of beer and vinegar, the role of micro-organisms came into light.

This lead to further progresses in selection and control methods, but it is the development of the food industry, notably after the second world war, that gave birth to the biotechnologies of today, aimed at producing a wide variety of better and safer foods under controlled conditions.

Main categories of micro-organisms

Micro-organisms responsible for the majority of food fermentations are classified into 3 categories:

· Yeasts
Yeasts are fungi, a division of thallophytes - non-vascular plants with little or no mycelium. They ordinarily reproduce by budding. They live in sugary solutions and ferment sugar. Among the yeasts used in food production one can mention as examples:

- genus Saccharomyces, common in bread, wine or beer making as well as in the
dairy industry (such as Sereveisae used in blue mould cheeses),

- genus Debaromyces, also used in the dairy industry.

· Moulds
Moulds are also fungi, but contrary to yeasts, they feed on organic matter and reproduce by means of spores. In this family, Penicillium roqueforti in Roquefort cheese and P. candidum in Camembert cheeses are well known.

· Bacteria
Bacteria are typically one-celled and multiply by simple division. They occur in three main forms: spherical (cocci), rod-shaped (bacilli) and spirilla.
· Among the immense family of bacteria one can give as examples:

- Genus Micrococcus present in the meat industry,
- Genus Oenococcus in the wine industry,
- Genus Lactococcus - also known as lactic bacteria - used in the dairy industry.

Micro-organisms can work alone, but they usually work in associations comprising a large number of gena, species and strains.

Lactic bacteria
Lactic bacteria include a great variety of micro-organisms used in the food industry. They are primarily used in the dairy industry but can also be used in a number of other applications. Although classification remains difficult and some times changes, one can distinguish at least a dozen of different types such as streptococcus, lactococcus, intrococcus, pediococcus, leuconostoc, bifido bacterium and lactobacillus.

Industrial usage

The lactobacilli are present almost everywhere in nature and are widely used in the food industry where they assure a consistent production of high-quality food products.

Dairy industry

In the cheese manufacture, the starter culture plays a crucial role during all phases of the cheese making and maturing process. As the culture grows in the milk, it converts lactose to lactic acid. This ensures the correct pH and it also assures the final moisture level and yield in the cheese. During ripening, the culture assures a balanced aroma, taste, texture and, if required, eye formation. Depending on the cheese type produced, the selection of the correct mixture of culture is essential in order to obtain a high quality product.

In yoghurt and other fermented milks the culture assures the development of the taste and texture of the final product. Depending on the level of pH, the product can be either mild or strong in taste. Depending on the amount of polysaccharides produced, the product can be more or less viscous.

Dairy products have long been valued as a source of healthy nutrition. Probiotic cultures in particular are known for this positive effect. These cultures are carefully selected strains; there are strong indications that they help improve digestion, balance the intestinal flora and safeguard the immune system.

Meat industry

The primary application for meat starter cultures is dried fermented products such as salami, pepperoni, chorizo and dried ham. In these products the lactic bacteria provide an optimal development of flavour and colour hereby ensuring correct drying condition and control of fermentation.

In addition a wide variety of moulds are used for surface ripening of sausages hereby preserving the natural quality of the product and assuring a controlled development of flavour.

Wine industry

In the wine industry, it is well known that yeasts are responsible for the alcoholic fermentation. Lactic bacteria also play an important role in wine making.They
are responsible for the malolactic fermentation that converts the unstable malic acid naturally present in wine into the stable lactic acid. This conversion is necessary in order to assure the stability that characterises high quality, long-hold wines.

Bread industry

In bread making, lactic bacteria are responsible for the fermentation, which is normally known as "sour-dough". This fermentation offers bakers a number of important benefits such as easily handled dough, uniformity, a shorter resting time, good aroma and longer freshness.

Agricultural industry

Lactic bacteria are used in the agricultural industry for a number of different applications.

In modern live stock production, pigs, cattle and chickens are often exposed to stressful conditions, which can give rise to imbalances in the intestinal flora with consequent low weight gains, increased diarrhoea incidence and high mortality rates. Lactic acid bacteria have proven very effective in restoring and maintaining a balanced intestinal flora in the animals, hereby ensuring optimal production parameters and improved well being of the animals.

Also in the preservation of silage, which is a fermentation of grass alpha-alpha or corn, lactic acid bacteria are used to assure an optimal preservation of the nutritive elements in these products.

Health food industry

In addition to the food and feed applications, lactic bacteria are also used in a wide variety of capsules and tablets specifically targeted at the health food industry. Modern day living often gives rise to imbalances in the intestinal flora of human beings. This imbalance can also be caused by travelling or medical treatment, and lactic acid bacteria can help in restoring and maintaining a balanced intestinal flora, hereby assuring a good quality of life despite changed conditions.

Production process and quality control

Production of lactic bacteria takes place in highly specialised fermentors under strict hygienic conditions. It typically involves a number of different steps:

1. The original strains are preserved in a microbiology laboratory that is responsible for - prior to each production - preparing the inoculation material. This inoculation material is transferred to fermentors in which the culture is allowed to multiply and grow within carefully defined and monitored conditions.

After the fermentation has been finalized, the bio mass is harvested, eg by means of centrifugation, and the resulting bio mass is conserved either in a liquid, frozen or powder form. Finally the product is formulated and packed in the finished product according to the customers' needs.

2. The entire production process is at each individual step carefully monitored by Quality Control laboratories in order to assure that the product remains of the highest quality and is free from contamination.

Physical form

Starter cultures are generally available in various physical forms, depending on the type of product and the application. Starter cultures are available in liquid, frozen or powder form and in different concentrations which allow either usage: directly in the final food product, or after reactivation by the food processor.

Quality control

Producers of lactic bacteria carry out a high level of routine controls of the methodology and regularly check the proper operation of the installations. But controls also include:

· Characterisation and monitoring of the strains which are used for preparation of the inoculation material

· The characteristics of the products at various production stages. Parameters are continuously checked by sensors that, when necessary, are backed up by data processing units and various automatic systems
· The safety aspects. The microbiological condition is monitored in order to detect any contamination that might occur. Should contamination be detected, production is stopped until the problem has been solved.

Official regulation

Since ancient times cultures have been an essential part of food production and the safety of lactic bacteria is well established. Official regulation has therefore been limited and varies from one country to another.