University of Khartoum

Impact of Raw Milk and Plant Quality Control Measurements on The Shelf Life of Pasteurzed Milk

Impact of Raw Milk and Plant Quality Control Measurements on The Shelf Life of Pasteurzed Milk

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Title: Impact of Raw Milk and Plant Quality Control Measurements on The Shelf Life of Pasteurzed Milk
Author: Mustafa Ahmed, Samia
Abstract: The present study was conducted to examine the effects of raw milk quality, pasteurization and storage conditions on the keeping quality and shelf life of pasteurized milk produced by Blue Nile Dairy Company (CAPO). Raw milk used is provided by Blue Nile Dairy and Kordi Farms. Raw milk from both dairy farms usually is mixed before processing. Milk fat is standardized to 3– 3.2% and the milk is pasteurized using a HTST pasteurizer. In the present study, raw milk was analyzed for some chemical, physical and microbial properties, 120 samples of CAPO pasteurized milk from six different batches were examined. These pasteurized milk samples were stored at both 5o C and 10o C. The analysis was carried out every second day up to 9 days for microbial, chemical and physical properties. The presence of Brucella antibody, antibiotic and phosphatase enzyme was also examined. The log total bacteria counts of pasteurized milk were found to be 2.534± 0.09 cfu/ml and 2.448± 0.064 cfu/ml, while log coliform bacterial counts were 0.235± 0.031 and 0.223± 0.034 cfu/ml for milk samples stored at 5o C and 10o C, respectively. The log of thermoduric counts of pasteurized milk revealed 1.492± 0.044 and 1.375± 0.047 cfu/ml and log psychrotrophic counts were 0.24± 0.066 and 0.481± 0.071 cfu/ml, respectively. Chemical and physical properties of pasteurized milk were conducted. The data showed that fat results were 3.33± 0.009 and 3.35± 0.001%, protein were 3.2± 0.021 and 3.22± 0.020% and lactose were 4.02± 0.02 and 4.01± 0.027% for the samples stored at 5o C and 10o C, respectively. The ash content revealed 0.717± 0.003 and 0.718± 0.003%, SNF 7.91± 0.023 and 7.91± 0.025%. Density was reported as 1.028± 0.088 and 1.028± 0.094 and freezing points (o C) were -0.448 ± 0.002 and -0.447 ± 0.002, respectively. Also the result showed that the titratable acidity was found as 0.141 and 0.145% and pH were 7.06 ± 0.002 and 7.07± 0.002, respectively. However pasteurized milk samples were found to be negative to the milk ring test, antibiotic and phosphatase test. The shelf life of pasteurized milk tested in the present study was 9 days. Hence it is concluded that the pasteurized milk produced by Blue Nile Dairy Company (CAPO) was of high quality. However raw milk supply needs improvement of hygienic quality.
Description: 85page
URI: http://hdl.handle.net/123456789/8202
Date: 2015-04-03


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