Contribution à l'étude de la protéolyse des laits réfrigérés et incidences sur le rendement d'une fabrication de fromages à pâte molle

Abstract - The authors study the influence of the initial leved of contamination of the milk by psychrotrophe bacteria, the influence of the storing time at + 4° C on the proteolysis of the casein and their incidental effects on the manufacturing yield of soft cheese.
According to reports it seems that initial contamination by psychrotrophe bacteria amounts to 500 - 2 500 germs / mL the possible storage duration is five days. On the other hand for 3 500 - 50 000 germs / mL a storage exceeding 3 days leads to an important psychrotrophe bacteria multiplication (5.10⁵ - 2.10⁶ germs / mL) and to a partial solubilisation of casein into polypeptides having a molecular weight between 5 000 et 20 000.
This proteolysis of highly contaminated milk stored under a long lasting refrigeration leads in cheese industry to a decreased yield in protidic nitrogen of approximately 5 p. 100.