Sampling Procedures for Bacterial Analysis of Prepared Frozen Foods

moderate speeds in unbaffled vessels is that due to low turbulence there is virtually no tendency to foam.Foaming is commonly observed in aeration systems which use baffled or indented flasks and depend for their efficacy on a high degree of turbulence and on the entrainment of air bubbles.Foam production interferes with aeration and has other undesirable effects.It may be reduced by chemical additives, but these additives themselves interfere with aeration.Corman et al. (1957) have shown that anti-foam agents may reduce the oxygen absorption rate drastically, in one case from 455 to 54 ml oxygen per 100 ml per hr.It is likely, therefore, that rolling aeration is more efficient than aeration by shaking with certain types of culture me- dia, since rolling aeration does not depend on bubble entrainment, does not generate foam, and eliminates the need for anti-foam agents.