Yeast have been reported to cause spoilage such as yeasty flavor and foamy appearance in all kind of cream products (Fleet and Mian 1987; Walker and Ayers 1970). In an Australian study 48% of the examined cream samples contained yeast in the range of 103-104 cfu/ml while a number of 104-105 were found in 14% of the samples (Fleet and Mian 1987). The yeast identified in the study were mainly C. famata, Rhodotorula glutinis, C. diffluens, Cryptococcus laurentii, and R. rubra. These yeast species all showed high lipolytic activity and were able to grow at 5°C.
An investigation from Italy showed yeast in 4 out of 5 butter samples examined (Minervini et al. 2001) The detected yeast included C. kefyr, C. guilliermondii, and S. cerevisiae in concentrations of 103-105cfu/g (Minervini et al. 2001). In 1987 Fleet and Mian found yeast in 7 out of 16 butter samples. The yeast occured in numbers below 103 per gram and belonged mainly to the species R. glutinis and Rhodotorula rubra. Lipolytic yeast on the butter surface has also been reported (Walker and Ayers 1970), but all together the literature on this subject is very limited.
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