Properties And Some Uses Of Ultrfilterated Milk:

Ezzat Abdel Khalik Ahmed Montasser

Increased cheese yield and savings in ecergy, ~ilkclotting enzymes, manufacturing time, and whey disposelhave evoked an interest in the use of milk pretreatedby ultrafiltration ( UP ) for cheese making. Ultrafiltratedmilk was used successfully in making soft cheeses.The Blue-veined cheese is a semi-hard mould ripenedcheese. It is made in Egypt from a mixture of Cows’and buffaloes’ milk.The use of imported milk ingredients in dairy productsis growing faatly in the last few years in Egyptdue to the lim1ted National milk supply.Therefore, this study was planned to evaluate themanufacture o~ Blue-veined cheese from ultrafilteredreconstituted skim milk and butter oil and compare itwith the cheese made by traditional process.To manufacture the UP-Blue cheese, the retentatefrom reconstituted skim milk ( 10% T.S. ) was mixed witheabout 14% anhydrous milk fat, homogenized at 65 C , coooled to )2 C and 2% Streptococcus lac tis was added.At acidity of O.26~, O.lg spores of Penicillium roquefortiper kg retentate and reunet were stirred in. followed by1% Na C1. After coagulation. it was cut and filled intomoulds. The sequence of other steps were as those madein the traditional method. The control ( traditionalcheese ( TR ) was made using fresh mixed cows’ and buffaloes’milk ( 1 : 1). Samples were taken for scoringand aLslysis after manufacture ar-d then every 15 daysfor four months.The results can be summerized as follows:-1 - The TS content in the retentate was about 2.4times of the control ( fresh milk). The fat / DMwag: 33.28 and 4).9% in milk and retentate respectively,while protein/ DM was 24.81 and 36.03~ inthe same order. Acidity percen t also was lower inthe milk than re tents te due to t~ high proteincontent in the latter. Lactose /DM in milk representedabout three folda- of that in the· retentate.cThe nitrogen and calcium distribution were differentin milk than retentate.2.. - The. anallsis- of the Blue-chee se showed that themoisture content was higher in UF than TR-Blue cheeseand it decreased during ripening in the twotypes, but it remained higher in the former thanthe TR-Cheese.3 - Fat content and total nitrogen contents were higherin the TR-than D7-Blue cheese and they increasedgradually during ripening till the end of the ripeningperio d •4 - Soluble N and N.P.N were higher in the UF-than theTR-Blue cheese at the begining and they increased”ith t ae ripening p rogress,5 - Lactose content was higher in OF-than TR-Blue cheesedue to the high moisture content of the UP-cheese.Lactose content decreased during ripening dueto fermentation.6 - After manufacture, the acidity percent was higherin TR-chees& than UP-cheese, and it increased tilltwo months and it decreased in the two types withthe ripening development. The pH took the oppositetrend, being lower in the TR than OF-cheese and itincreased during ripening and they were the same atthe end of the curing process.7 - The flavour components including TVFA, total carbonyland monocarbonyl compounds were higher in theUP than TR-Blue cheese and they increased graduallyduring ripening process in the two types8 - The amount of soluble tyrosine and tryptophan tookthe same trend as well as in all cheeses. Theyincreased with progressive increase in proteinbreakdown during ripening rapidly at first, thenthe rate of increase declined.9 - The electrophoretic pattern showed th~t the breakd07ffiof pr’J~ein during ripening ’Has hister in tc.eUP-than TR-Blue cheese.10 _ Quantitative changes in free fatty acids and freeamino acids occurred during the ripening were discussed.11 - Scoring of cheese indicates that cheese made fromretentate ( W-Blue cheese ) proceeds more- rapidripening than that made by tradi tional me thod andit had a smooth, creamy and spreadable body with asharp and peppery navour which is desired in thistype of cheese.12 - The correlation coefficient and T test between thescore panel test and other determined chemical valueswere statistically calculated to evaluate theripening process.