University of Khartoum

Effect of Processing and Storage Conditions on the Chemical Composition and Microbial Quality of White Soft Cheese

Effect of Processing and Storage Conditions on the Chemical Composition and Microbial Quality of White Soft Cheese

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Title: Effect of Processing and Storage Conditions on the Chemical Composition and Microbial Quality of White Soft Cheese
Author: Ahmed, Asma Ahmed Ibrahim
Abstract: The effect of processing and storage conditions on chemical composition and microbial quality of white soft cheese was studied. White soft cheese was made from pasteurized cow’s milk (72oC/1 min) with 2% salt added to milk, followed by the addition of 0.02% and 0.04% CaCl2 in two separate batches. After manufacture, cheese was stored in 2% and 4% brine solution for 48 hr, then cheese was preserved in plastic bags without brine solution and cans with brine solution at 9oC for 45 days. Chemical and microbial analyses of cheese were determined at 15-day intervals. Results showed that fat, protein and total solids contents were higher in cheese made with 2% NaCl (27.28±2.95, 14.86±3.30 and 48.0±7.64% respectively), while ash content was higher in cheese made with 4% salt (2.22±0.43%). The acidity was higher in cheese made with 2% salt (0.461±0.218%). The fat, protein and total solids contents were higher in cheese made with 0.02% CaCl2 (26.84±3.39, 15.19±3.64 and 48.03±8.93% respectively), while ash content and acidity were higher in cheese made with 0.04% CaCl2 (2.02±0.58 and 0.496±0.199% respectively). The fat content had slightly increased to 27.00±2.78% at day 15 followed by a decrease to 25.38±4.18% towards the end of storage period. The protein content had increased to a maximum of 15.30±4.09% at day 30, then decreased to 14.23±3.65 at day 45. The total solids content had gradually decreased from 48.82±7.77% at the 10 beginning to 45.22±9.17% at the end of storage period. The ash content gradually decreased from 2.30±0.52% at day zero to 1.73±0.34% at day 45, while acidity increased from 0.350±0.120% at the beginning to 0.520±0.193% at the end of storage period. The fat (27.91±1.87%), protein (17.71±1.84%), total solids (55.17±3.00%), ash (1.98±0.43%) contents and acidity (0.508±0.196%) were all higher in cheese stored in plastic bags compared to that stored in cans (24.66±3.36%, 11.72±1.43, 39.54±5.32, 1.91±0.57 and 0.401±0.209% respectively). The total bacterial count was higher (log10 9.67±0.40) in cheese made with 4% salt, while lactic acid bacterial count was higher (log10 8.92±0.78) in cheese made with 2% salt. Coliform bacterial count was higher in cheese made with 2% salt (log10 5.48±3.16), while Staphylococcus aureus count was higher in cheese made with 4% salt (log10 7.14±2.65). The total bacterial count was higher in cheese made with 0.04% CaCl2 (log10 9.74±0.35), while lactic acid bacterial count was higher in cheese made with 0.02% CaCl2 (log10 8.91±1.13). Coliform bacterial count was higher in cheese made with 0.02% CaCl2 (log10 5.83±2.97) compared to that made with 0.04% CaCl2 (log10 4.57±3.47), while S. aureus count was higher in cheese made with 0.04% CaCl2 (log10 7.41±2.10). During storage period, the mean value of total bacterial count increased to a maximum of log10 9.88±0.34 at day 30, then slightly decreased to log10 9.79±0.50 at the end of storage period. The lactic acid bacterial count increased to a maximum of log10 9.30±0.68 at day 1115, then decreased to log10 8.46±1.27 at day 30 and again increased to log10 8.98±0.68 at the end of storage period. Coliform bacterial count decreased from log10 7.29±0.89 at the beginning to log10 1.88±2.39 at the end of storage period. S. aureus count decreased to a minimum of log10 6.06±3.57 at day 15 before increasing to log10 8.36±0.95 at the end of storage period. Cheese stored in plastic bags had higher count of total bacteria (log10 9.77±0.42), lactic acid bacteria (log10 9.04±0.84) and coliform bacteria (log10 5.32±3.09), while cheese stored in cans had higher S. aureus count (log10 7.15±2.66).
Description: 2003
URI: http://khartoumspace.uofk.edu/handle/123456789/10429
Date: 2015-05-10


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