Psychrotrophic Bacterial Contamination of Milk And Some Dairy Products

One hundred random samples of raw milk (50 samples);pasteurized milk (25 samples) and cream localities(25 samples) were collected from different iocalities In SharkiaGovernorate for enumeration, isolation and identificationof Psychrotrophic bacteria. The counts was determinedaccording to the technique recommended by APHA (1985)uSIng standard plate count agar and incubated at 7vC/l0days, as well as u s i ng modified rapid method (32uC/2days) .The mean values of Psychrotrophic bacterial countsusing standard method were, 1.2xlO , 2.5xlO ,4.5xlO and1.5xl08 of raw milk samples obtained by hand milking; bymachine milking, pasteurized milk and cream samplesrespectively. While their counts by modified rapid method (32.C/2 days)were, 1.8xlO , 2.6xlO ,2.3xlO and 1.6xlO respectively.High correlationexists between the Psychrotrophiccounts using standard and modified rapid method (r=0.92;0.84; 0.90 and 0.78 respectively). Therefore, modifiedrapid method has been recommended for Psychrotrophiccount in milk and dairy products.Out of 166 isolated Psychrotrophs (7uC/IO days) fromraw milk, obtained by han d m i Li i ng , 40 (24.1%) werePseudomonas spp.; 21 (12.7%) Aeromonas spp.; 16 (9.6%)