THE INFLUENCE OF HYPOTHERMIC SHOCKS AND ADDITIONS DURING PROCESSING, ON SOME YOGHURT FEATURES

摘要

In this work there was searched the influence of some hypothermic shocks and compound admixtures, during yoghurt processing, on some yogurt features (pH, titratable acidity and curd aspect). The biological material used in this work was represented by cow milk, inoculated with a starter culture of thermophile lactic bacteria, including two different species: Streptococcus termophilus and Lactobacillus bulgaricus. The experiments during yoghurt processing have consisted in subjecting of samples to hypothermic shocks, on the one hand, and introducing of some admixtures (starch or gelatin), in certain proportions, on the other hand, to see the influence of these experiments on the evolution of pH, titratable acidity and quality characteristics of yoghur curd particles. The application of hypothermic shocks in the early period of thermostating has determined the decrease of fermentation activity of lactic bacteria (expressed by reduction of titratable acidity values) and has made the coagulation process of milk to be blocked. The later applied hypothermic shock, the lower effect on titratable acidity and coagulation process was. The addition of gelatine or starch during yoghurt processing has influenced, indirectly, the fermentation activity of lactic bacteria. The gelatin addition has led to the increase of titratable acidity values, comparing to blank. The addition of gelatine or starch has not rushed the milk coagulation during yoghurt processing. Compared to the control, in samples with admixtures the curd formation was slower, especially in those ones with starch addition.