Related Experiment Video
Updated: Apr 27, 2026

The Cultivation, Growth, and Viability of Lactic Acid Bacteria: A Quality Control Perspective
Published on: June 16, 2022
The yogurt amino acid profile's variation during the shelf-life
A Germani1, R Luneia2, F Nigro1
1Departmentpt of Experimental Medicine, RU of Food Science and Human Nutrition, Sapienza University of Rome, Italy.
Objective:
To analyze the yogurt amino acid profile starting from marketing through the whole shelf-life. The evaluation of the proteolytic activity of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophilus, allows to deduce their vitality during the shelf-life period and within 45 days.
Methods:
Three types of full fats yogurts have been analyzed (a) natural white (b) sweet white and (c) whole fruit - in two stages: t0 (first day of shelf-life) and t1 (end of shelf-life). The proteins have been analyzed by the Kjeldahl method and the amino acid profile by HPLC.
Results:
In natural yogurt a significant increase of the amount of free amino acids has been observed during the period of shelf-life (97%). In the sweetened full fats and fruit yogurt, instead, there is a lower increase of respectively 33% and 39%
Conclusions:
In whole milk natural yogurt, based on our data, the proteolytic activity seems to persist during the entire period of the shelf-life and this can be considered an index of bacterial survival, especially of Lactobacillus delbrueckii subsp. bulgaricus during the marketing process.
Related Concept Videos
Microbes in Food Production
Production of Organic Acids
Microbes in the Production of Fermented Foods
Drug Product Stability
Amino acids
Bacterial Protein Maturation

