Yeasts and moulds

Yeasts and moulds – they get everywhere!

Fungi (yeasts and moulds) cause a variety of problems throughout the food industry – some of which are ‘hidden’. Some fungi are also very useful to the industry – such as in the production of bread products and alcoholic drinks.

For a scientific overview of the problem issues in the food and drink manufacturing environment, Yeasts and moulds - occurrence and control in the food factory (Campden BRI Review 58) is particularly useful: see for more details. Also of relevance is Food microbiology: an introduction (Key Topic 12): see

This brief factsheet highlights the major areas of interest and concern, and how the issues manifest themselves. It looks at the end problem and indicates where or how the problem originated. We have expertise in all of the areas highlighted, so if you have an issue of any type with yeasts or moulds, contact us on

Although this factsheet concentrates on the problems caused by yeasts and moulds, they are of course vital to the production of alcoholic drinks and bread. We have specialist sections within Campden BRI with a century of expertise – see our website at for details of services offered within the brewing and cereals sectors. We also have expertise in how fungi are used in agricultural situations – e.g. as biological control agents.


Yeasts and moulds can cause spoilage – detectable by sight, smell or taste. Spoilage is not usually associated with an immediate health concern, but it is often detectable when the degree of spoilage is very low. The first indication that there is a problem is when a consumer contacts you with the comment “this product tastes or smells a little bit ‘off’”. This will immediately trigger a series of questions: what is the taint?, what organism caused it? and how did it originate? To answer these needs a variety of skills, preferably within the same organisation. In some cases, we will have come across this problem previously. If so, we can make informed suggestions on what may be causing the issue.

Deciding what the taint is can be done by both sensory experts and analytical chemists. The sensory team can assess the taint or odour and accurately describe its characteristics. The chemists can then take this information and target analyses to try and detect and quantify what is causing it. In practice they often work together to make an informed prediction of what might be causing the problem. Recently for example, we have seen a number of incidences where 1,3–pentadiene has been produced by the mould–mediated degradation of the preservative sorbic acid in fruit beverages. The pentadiene has a strong “petrol–like” odour associated with it.

Contact an expert