A Study of the Changes Occurring in the Fat Constants of Milk Fat of Cheddar Cheese During the Ripening Process

Abstract

The changes occurring in the fat constant values of cheese fat were detd. during the ripening of Cheddar cheese as a result of pasteurization of the milk, homogenizatioh of pasteurized milk, and addition of starter distillate, propionic, citric and acetic acids. Pasteurization of the milk reduced the rate of hydrolysis of fat in the cheese as indicated by lower acid value, Polenske and Reichert-Meissl numbers, when compared with the fat constant values of raw milk cheese. Homogeni-zation of pasteurized milk at low pressures (300 lbs.) produced no significant changes in the fat constants of the cheese fat. Addition of acetic acid to the cheese curd caused > 300% increase in acid number during aging whereas citric and propionic acids produced only 60% to 70% increase. The Reichert-Meissl values for these samples were uniformly higher at the conclusion of the study than at the start, indicating an increase in the water-soluble, volatile acids during aging. The Polenske values decreased during the same period showing that water-insoluble, volatile acids were reduced. The percentages of soluble acids increased and the percentages of insoluble acids tended to decrease, giving further evidence of hydrolysis of the cheese fat. However, addition of acetic and propionic acids in the quantity used produced undesirable defects in the flavor of the cheese.