The Bacteriology of Brick Cheese. I. Growth and Activity of Starter Bacteria during Manufacture

Abstract

A study was made of some of the bacteriological, chemical and physical changes in Brick cheese during its manufacture. The following results were obtained:1.When Brick cheese was manufactured by the conventional method from raw or pasteurized milk:a.With Str. lactis as the only starter special care was required in the control of the moisture at dipping, otherwise a sour flavor and a weak or crumbly body developed. If the moisture content at two days was higher than 42 per cent, the above defects developed in the cheese.b.With Str. thermophilus as the only starter a fermented flavor and open texture developed in the cheese.c.With a combination of the above two starters, a better quality of cheese was produced than when either was used alone.2.During the manufacture of Brick cheese, the growth and activity of the starter bacteria were as follows:a.Str. thermophilus practically stopped growth at the third or fourth hour after dipping because of the relatively low temperature in the cheese.b.The growth and activity of Str. lactis were not very extensive until the latter part of the draining period. It usually reached its maximum numbers within one or two days. When the original inoculum was large (0.5 per cent or more) growth and activity were more extensive during the early part of the draining period.3.The cooking temperature could not be raised above 106° F. without greatly retarding the growth and activity of Str. lactis. However, a cooking temperature of 112° F. increased the rate of growth and activity of Str. thermophilus.