50-5

M. M. FENN, D. K. Larick, and L. G. Turner. Dept. of Food Science, North Carolina State Univ., Box 7624, Raleigh, NC 27695-7624

To increase the market competitiveness of reduced-fat cheese products, adjunct cultures, elevated temperatures, fat replacers, and enzymes have been used. Specifically lipolytic and proteolytic enzymes have been used to promote and accelerate flavor development within Cheddar cheese.

Previous research in this lab produced and characterized cheese flavor hydrolysates from milk utilizing commercial enzymes. This research was designed to incorporate these hydrolysates into reduced-fat Cheddar cheese and characterize volatiles, non-volatiles and sensory attributes.

Flavourzyme (protease) and palatase (lipase) were used to derive flavor concentrates from Parmalat UHT milk. Hydrolysates were added during curd formation. A control and the enzyme modified cheese were ripened for 2, 4, and 6 months and descriptive sensory analysis was conducted. Lipolysis and proteolysis were monitored during ripening by free fatty acids (FFA) and percent hydrolysis, respectively. Volatiles were characterized and identified with gas chromatography (GC) and GC-mass spectrometry, respectively. The relationships between analytical and sensory data were examined using multivariate statistics.

Hydrolysates that contained both flavourzyme and palatase produced the highest total concentration of volatile compounds. Statistical analysis suggested synergism between enzymes; the combination masked bitter peptides that were seen in protease only hydrolysates and it had the highest liberation of FFA (C4 to C18). Cheese samples with lipase and lipase/protease combinations showed a notable increase in FFA when compared with the control. The protease increased the formation of secondary products, such as sulfides that resulted in an increased sulfur flavor. Thus use of enzymes can be a valid mechanism for the development of cheese sensory attributes in reduced-fat products.

This research demonstrated the impact of proteolysis, lipolysis, and the combination of the two on flavor of reduced-fat cheese. This information can be used by industry to design enzyme-modified cheese technology.