ABSTRACT
Carbon dioxide and flavor compounds resulting from the growth of certain species of the genus Propionibacterium may be either beneficial or deleterious during the ripening of certain popular cheese varieties. The variety of possible uses makes the propionibacteria a worthwhile subject for discussion. In truth, there has been comparatively little attention given to them in the dairy and food literature as starter cultures compared with the mesophilic lactic streptococci. In regard to their most important present-day usage in foods, that is to say cheese, contemporary improvements in farm sanitation, milking practices, and refrigeration have increased the necessity of understanding and using carefully selected and nurtured cultures of propionibacteria. Isolation of propionibacteria from fermented dairy products, notably cheese, presents no particular problems. Initial explanations of the role of propionibacteria in cheese flavor production are now known to have been unrealistically simplified.
