Assessment Of Chemical And Microbiological Quality Of Stirred Yoghurt In Khartoum State Sudan

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Mohammed Hassan Mohammed Haj
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University of Khartoum
This study was carried out on stirred yoghurt samples purchased from the market. The stirred yoghurt was produced by Blue Nile Dairy Company (CAPO). Sixty samples were transported to the Faculty of Animal Production, laboratory to assess the chemical, microbiological content and shelf life of stirred yoghurt. Chemical and microbiological analysis were carried out on the first day of manufacturing and after 2, 4, 6, 8 and 10 days. Ten samples from six batches were examined. The investigations involved the analysis of fat, protein, lactose, ash, total solids, solids non-fat and measurement of pH, acidity and viscosity. Microbiological determinations were conducted for the identification and classification of lactic acid bacteria and enumeration of total bacterial count. The chemical analysis for stirred yoghurt results showed that the fat ranges were 1.60–4.90%, protein were 1.61–5.36%, lactose were 6.75–10.92%, ash were 0.54–0.99% and total solids were 14.02– 17.74%, solids-non-fat were 11.34–14.52%, acidity were 0.80–1.50%, pH were 3.52– 4.72% and viscosity were 38.30–82.70%. The corresponding averages were 3.12%, 3.32%, 8.80%, 0.83%, 16.06%, 12.93%, 4.08%, 1.00% and 63.60%, while the microbiological isolation results showed Streptococcus thermophilus and Lactobacillus bulgaricus. The total viable bacterialm count log of these organism ranged 7.00–7.78 and the average 7.33, 7.00–7.78 and the average 7.35, respectively. The log of total bacterial count (cfu) ranged from 7.00 to 8.78 and the average was 7.47. The results indicated that the storage period had significant (P< 0.001) effect on the chemical composition except on the total solids and viscosity. Also there were significant (P< 0.01) effect of the storage period on the microbiological evaluation of stirred yoghurt.
A thesis submitted in partial fulfillment of the requirements for the Degree of Master of Dairy Production and Technology
University of Khartoum chemical quality microbiological quality stirred yoghurt
Mohammed Hassan Mohammed Haj, Assessment of chemical and microbiological quality of stirred yoghurt in Khartoum State-Sudan .- Khartoum : University of Khartoum, 2006 .- 88p. : illus., 28cm., MS.c.