Bitter Flavor in Cheddar Cheese

Bitter flavor is frequently found in Cheddar cheese.It may be only slightly apparent, or may actually make the product unpalatable.This defect has been observed by numerous workers, some of whom have been able to show specific causes for it.The typical citations which follow illustrate the variety of causes which have been indicated.Publow ( 1) attributed bitter flavor in cheese to undesirable organisms, dirty cows, old starters and unclean or rusty milk cans.Allen (2) found it in cheese made from milk of inferior quality.He observed that alkali-forming and protein-splitting bacteria were present in larger numbers in the inferior milk than in clean milk, but that there was a marked tendency for the development of these organisms in the cheese made from clean milk, rather than in that made from inferior milk.Some investigators believe that the defect can be traced to certain microorganisms.Hucker and Marquardt (3) were able to associate bitter flavor with S. paracitrovorus and certain strains of acid-proteolytic cocci.S. paracitrovorus in raw milk showed slightly bitter flavors after twelve weeks, which did not occur in cheese made from identical milk with Hansen's culture.In pasteurized milk S. paracitrovorus also showed slightly bitter flavor.Acid-proteolytic cocci gave a decidedly bitter flavor in two to three weeks which eventually made the cheese unpalatable.Riddet, Valentine, and Whitehead (4) described a bitter flavor which they produced by using a particular starter culture which had become a rather weak acid producer in the cheese vat.Bitter or metallic flavor was also found in the starter itself, as well as in the cheese.They added, however, that not all" slow" or bitterflavored starters produce bitter cheese.Riddet, Valentine and Whitehead (4), in reviewing the possible causes of bitter, flavor, observed that cheese made in their laboratory from normal milk, not overheated during pasteurization, frequently developed bitterness at an intermediate stage in the ripening process.The bitterness sometimes disappeared subsequently and the Cheddar flavor developed in an otherwise normal manner.This cycle had previously been observed by Allen (2) who noticed that bitterness in cheese made from inferior milk developed after four weeks and disappeared after sixteen weeks of curing.Kelly (5) commented on this sequence by stating that "many investigators who have studied the ripening processes in cheese have considered thak the peptone