QUALITY OF PROCESSED CHEESE SPREAD MADE USING ULTRAFILTERED RETENTATES TREATED WITH SOME RIPENING AGENTS

A study was made on the use of rapidly ripened ultrafiltered retentates in the manufacture of processed cheese spread. An initial study was made to evaluate the effectiveness of some ripening agents in accelerating flavour development in the retentates. The results showed that good-quality flavour could be obtained by using a combination of 0 . 05\% sodium dodecylsulphate (SDS) and 0 . 005\% of a commercial lipase preparation after incubation at 32 degrees C for 5 days. Mature Ras cheese used for the manufacture of processed cheese spread was replaced by SDS-lipase-treated retentates at levels of 0, 20, 40, 60, 80 or 100\%. The resultant cheese spreads were stored for 3 months at refrigerator (5-8 degrees C) or rooms temperature (20-25 degrees C), The results indicated that increasing the level of replacement of mature cheese by a ripened retentate tended to increase the moisture content in the resultant cheese spreads. However, this treatment did not significantly affect the fat, salt or pH values of the resultant product. Levels of soluble N, non-protein N and total volatile fatty acids in the experimental processed cheese spread were significantly higher than in the controls. This was more marked during storage at room temperature than at 5-8 degrees C. Increasing the level of ripened retentate used tended to increase the numbers of total bacteria, spore-formers, and proteolytic mid lipolytic bacteria in the cheese spreads, especially those stored at room temperature. Processed cheese spreads containing rapidly ripened retentates had good melting properties. Replacing up to 80\% of mature Ras cheese solids by SDS-lipase-treated retentate gave a product with flavour, consistency and colour superior to the controls, when fresh or after storage.