Bacteriological quality and safety of raw beef from selected outlets in Windhoek (Namibia)
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Date
2017
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Publisher
University of Namibia
Abstract
Inappropriate slaughtering and retail operations can compromise food safety specifically in densely populated areas like informal markets. The bacteriological quality and prevalence of Salmonella spp. and Escherichia coli O157:H7 on beef samples from the three different outlets (supermarket, butchery and open market) were assessed to determine their safety for human consumption. A total of 138 of beef samples were collected at random from three different outlets. The bacteriological quality of the beef samples were performed using the total plate count and total coliform count method, while standard culture methods were used for Salmonella spp. and E. coli O157:H7 isolation and detection. Based on results, the mean total plate count of beef from the open markets, butchery and supermarkets were 3.83 Log CFU/g, 3.90 Log CFU/g and 4.31 Log CFU/g, respectively. The mean TPCs on beef samples from supermarket A, B, C, D, E and F were 4.72, 4.87, 4.38, 4.90, 3.48 and 2.61 Log CFU/g, respectively. The mean TPCs on beef samples from open market X, Y and Z were 4.33, 4.28 and 2.95 Log CFU/g, respectively. The mean coliform count of beef samples from the open markets, butchery and supermarkets were 2.08 Log CFU/g, 1.71 Log CFU/g and 1.31 Log CFU/g, respectively. The mean CCs from supermarket A, B, C, D, E and F were 1.49, 2.80, 0.33, 0.00, 2.74 and 0.93 Log CFU/g, respectively. The mean CCs on beef samples from open market X, Y and Z were 2.59, 2.80 and 0.89 Log CFU/g, respectively. Based on the results, only 25.0 % of beef samples tested for total plate count and 26.4 % of samples tested for total coliform count exceeded the acceptable limit. The overall prevalence of Salmonella spp. and E. coli O157:H7 on beef samples were 68 (49.3 %) and 8 (5.80 %) respectively. The prevalence of Salmonella spp. on beef samples from the open market 31 (67.4 %), followed by butchery 24 (52.2 %) and lowest prevalence from supermarkets was 13 (28.3 %). The highest prevalence of E. coli O157:H7 on beef samples from open markets was 5 (10.9 %), followed by butchery 2 (4.35 %) and supermarkets 1 (2.17 %). The prevalence of Salmonella spp. on beef samples from supermarket A, B, C, D, E and F were 33.0 %, 22.0 %, 0.00 %, 57.0 %, 50.0 % and 20.0 %, respectively. The prevalence of Salmonella spp. on beef from open market X, Y and Z were 75.0 %, 63.0 % and 50.0 %, respectively. The prevalence of E. coli O157:H7 on beef samples from supermarket A, B, C, D, E and F were 0.00 %, 0.00 %, 0.00 %, 0.00 %, 0.00 % and 20.0 %, respectively. The prevalence of E. coli O157:H7 on beef samples were 13.0 %, 0.00 % and 21.0 % from open market X, Y and Z, respectively. A significant correlation (P<0.01) was found between TPC, TCC, Salmonella spp. and E. coli O157:H7. Beef collected from the outlets had low microbial counts and hence fit for human consumption. However, there was presence of Salmonella spp. and E. coli O157:H7 in beef samples from the outlets that can pose serious threat to the consumer and hence, testing may be necessary to avoid foodborne disease outbreaks
Description
A thesis submitted in fulfillment of the requirements for the Degree of Master of Science
Keywords
Bacteriology, Beef, Prevalence