Supporting probiotics in yoghurt

The dairy industry is increasingly turning towards innovation in order to drive sales forward. With the health trend gaining pace by the week, a key element of recent developments in the industry is the use of probiotics in yoghurts. But what problems does the creation of such a product pose for the food scientist?

A European project, co-ordinated by VTT Biotechnology and involving 64 research groups from 16 European countries, aims to provide a clearer understanding of the relationships between food, intestinal bacteria and human health and disease.

The PROEUHEALTH​ cluster is also looking at probiotic therapies against intestinal infections, chronic intestinal diseases, and for healthy ageing, as well as immunomodulation by probiotic bacteria, the development of new food-based vaccine delivery systems and commercial opportunities for food and pharmaceutical industries.

According to researchers, the probiotic bacteria need to survive several steps, including processing treatments, storage conditions and tolerating the conditions in the human body in order to be beneficial for the consumer. The probiotic bacteria need to reach the right spot in the human body, especially the gut, to be effective. The EU-funded project is exploring various factors that influence the viability and stability of probiotic bacteria through these several steps using yoghurt as one of the model products.

In yoghurt, acidity of the product (pH), storage temperature and storage time influence the viability of probiotic bacteria. Maintaining the storage temperature at +4 degrees C, reflecting refrigerator conditions, was the most important factor in keeping the probiotic bifidobacteria viable during the four-week storage time, report the scientists this week.

The viability was to some extent improved if the acidity increased. Most damaging for probiotic bacteria was storing the products at room temperature, and so keeping the probiotic yoghurts properly chilled during storage is a key issue for their ability to provide health benefits.

After reaching the consumer in prime condition, probiotic bacteria have to encounter the stressful acidic conditions and bile solutions in the human body. There are several strains of probiotic bacteria and the ability of these strains to live through different stress factors varies. Current research is attempting to find out how different technological factors (like freezing or heating treatments) can affect the viability of probiotics and whether these treatments have a later impact on the survival rate of bacteria.

Sometimes a suitable amount of stress makes the bacteria more enduring towards other stressful events. The probiotic bacteria can also be protected by combining them with growth-promoting substances. These so-called prebiotics can specifically support the survival of certain strains, but finding the suitable pro- and prebiotic pairs requires further studies.

The ultimate aim of scientists involved in the PROTECH project is to produce a model that can maximise the viability of probiotics through food processing. In so doing, they will enable food manufacturers to create a product that offers consumers a better guarantee that the probiotic products they purchase live up to the claimed health benefits.