Simultaneous growth and production of metabolite compounds by yoghurt starters and probiotics: a metabolomics approach
Supervisors:Prof.Dr.Ir. Toon van Hooijdonk (PDQ-WUR)
Prof.Dr.Ir. Marcel Zwietering (FHM-WUR)
Ir. Hein van Valenberg (PDQ-WUR)
Dr.Ir. Rob Nout (FHM-WUR)
July 2009 - June 2013
Commission on Higher Education of the Royal Thai Government
Yoghurt quality relies on two main sensory characteristics, flavour and texture. These aspects are determined by a wide range of factors such as composition and pre-treatments of base milk, strains of starter cultures used, fermentation process and storage conditions. Proto-cooperative growth of starter cultures, S. thermophilus and L. delbrueckii subsp. bulgaricus, has been well recognised for the production of traditional type of yoghurt. These lactic acid bacteria do not only determine the acidity of product, but also the formation of its distinctive flavour and texture characteristics. Nowadays, a different type of yoghurt is additionally inoculated by bacteria associated with good intestinal balance referred as “Probiotics” which can help maintain a favourable intestinal microbial environment and result in several therapeutic benefits. However, many probiotic bacteria grow poorly in milk and do not survive well; in addition, they may change the sensory characteristics of product. For example, thin texture and off-flavour are the two sensory defects found in probiotic yoghurt. However, the available information on the causes of these drawbacks is still limited.
This project is aimed to study the growth of different strains of probiotic bacteria, Lactobacillus rhamnosus GG, Lactobacillus plantarum WCFS1 or Bifidobacterium animalis Bb12 together with traditional yoghurt starter cultures during fermentation and storage. Their associative growth, viability of probiotic bacteria, ability to produce lactic acid and several metabolite compounds in yoghurt will be investigated. Understanding these features is essential for developing models that can help to predict the optimum growth conditions of probiotic bacteria in yoghurt yielding in significant higher quality products.
Working approach1. Study the influence of milk composition on the growth and proto-cooperative behaviour between several selected probiotic bacteria, L. rhamnosus GG, L. plantarum WCFS1 or B. animalis Bb12, and traditional yoghurt starter cultures, S. thermophilus and L. delbrueckii subsp. bulgaricus
2. Evaluate the viability of probiotic bacteria during set yoghurt fermentation and storage
3. Study relevant biochemical impacts in set yoghurt produced by addition of probiotic bacteria especially in production of metabolite compounds via 1H-NMR combining with SPME GC-MS or LC-MS technique
4. Generate information and explorative models that illustrate the simultaneous growth, viability and metabolites production of yoghurt starter cultures and probiotics in yoghurt fermentation
References1. Courtin, P. & Rul, F. (2004) Interactions between microorganisms in a simple ecosystem: yogurt bacteria as a study model. Lait 84(1-2), 125-134.
2. Saccaro, D.M., Tamime, A.Y., et al. (2009) The viability of three probiotic organisms grown with yoghurt starter cultures during storage for 21days at 4 °C. International Journal of Dairy Technology 62(3), 397-404.