6. Ropiness caused by Enterobacter usually is

A. worse at the middle of the milk
B. worse at the bottom of the milk
C. worse near the top of the milk
D. all of these

7. A brown color in milk may result from

A. Pseudomonas putrefaciens
B. the enzymatic oxidation of tyrosine by P. fluorescens
C. both (a) and (b)
D. S. marcescens

8. Which of the following species of Clostridium is responsible for the formation of dark green to black colors in cheese?

A. Clostridium tyrobutyricum
B. Clostridium sporogenes
C. Clostridium herbarum
D. None of these

9. Certain strains of Streptococcus lactis var. maltigenes may produce

A. bitter flavor
B. acid flavor
C. burnt or caramel flavor
D. none of these

10. The acidity may be described as “aromatic” when

A. Lactic streptococci and aroma forming Leuconostoc species are growing together
B. Streptococcus lactis and other lactis are growing together
C. appreciable amounts of volatile fatty acids are produced by Coliform bacteria
D. all of the above