Cheese bacterial growth

In the presence of all amino acids in the medium bacterial growth is facilitated, since amino acids are incorporated into proteins in a readily available form. Preparation methods of casein hydrolysate were found to have important effects on propionibacterial growth. Mixtures of amino acids produced by alkaline, acid and trypsin hydrolysis were tested (Zodrow et al., 1963a) and the best result was achieved with the trypsin hydrolysate. It was suggested that in this case tryptophane is preserved and some peptides are formed which have specific stimulatory effects on the bacterial growth. Nitrate inhibits the deamination of amino acids in cheese by propionic acid bacteria (Peltola and Antila, 1953). 

Sodium is also important in forming the texture of cheese, limiting bacterial growth and dehydrating cheese, thereby helping to form the rind. Most processed meats, e.g., ham and bacon, have added salt to season and cure the meat. Salt also inhibits bacterial growth and helps to emulsify the fat in sausages. 

Galesloot, T. E. 1957. The effect of nisin upon the growth of bacteria which are concerned or possibly concerned in bacterial processes in cheese and processed cheese. Ned. Melk. Zuiveltijdschr. 11, 58-73. (Dutch)... 

While studying the antifungal activity of L. rhamnosus on mold growth in commercial cottage cheese, Stiles, Carter, and Bullerman (2002b) reported that when live bacterial cells were added to cheese that was simultaneously inoculated with P. commune and A. niger, mold growth was reduced 40% and 70%, respectively, after 10 days of incubation. 

The application of fermentation processes in the production of foodstuffs continues to be a field of constant growth and economic value. For example, the development of a bacterial strain that produces rennin, a compound that is used as a coagulant and ripening agent in the production of cheese, is reported to represent a potential cost reduction in cheese manufacturing in the United States of at least 500,000 annually. 

EMCs are generally manufactured from cheese pastes that are made from the cheese of the same type. Additional components such as butterfat or cream may be added to add extra precursors when appropriate. Noncheese ingredients such as MSG, yeast extract, diacetyl, or other flavorants may also be added, but they may have to be declared on the label of the final product. Consistency in this base material is critical to the production of a standardized EMC product. Off-flavors may develop during incubation of the paste/enzyme slurry since the conditions are optimal for microbial growth. Equipment must be sterilized and precautions taken to prohibit miCTobial contamination. Bacterial inhibitors such as nitrates, sorbate, or nicin may be used. Free fatty acids generated by lipase enzymes afford some inhibition. Incubation time and temperature influence enzyme action and must be carefully controlled. 

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