YEAST EXTRACT CAN ACCELERATE FERMENTATION TIME OF YOGURT.

Researchers at the University of the Free State investigated whether the fermentation process in manufacturing yogurt could be accelerated on the premise that if successful, the cost of production should decrease. For that purpose they used as additive a water soluble auto-lysate of yeast, which is usually utilised for microbial growth support.

The yeast extract resulted in a decrease of fermentation time by 21% to reach a pH of 4.6. However, the yeast extract resulted in unacceptable flavour and taste. With further break down, using size exclusion chromatography, the researchers could isolate a fraction of the yeast extract which appeared to be responsible for the observed 21% decrease in fermentation time. This fraction contains molecules of low molecular weight, consisting of minerals, free amino acids and peptides. They ascribed the acceleration of the yogurt fermentation to the short peptides in this fraction.

Whereas the marked reduction in fermentation time is promising, this work will have to be taken further. It nevertheless suggests that application of the yeast extract fraction in industrial yoghurt manufacture could result in savings for both the industry and the consumer. The proviso of course is that time delays of other processes in the manufacturing plant are not overwhelming.

Reference:

Smith, E-A., Myburgh, J., Osthoff, G. & de Wit, M., 2014. Acceleration of yoghurt fermentation time by yeast extract and partial characterisation of the active components. J. Dairy Res. 81, 417-423.