Evaluation of the Bacterial Load in the Raw Dairy Products in Baghdad, Iraq

Abstract

Milk and cheese were recognized as highly nutritious food due to their high protein, fat and minerals (calcium, phosphorus, iron, and vitamins). Accidental contamination of food through the handlers could have resulted in many kinds of bacteria especially Staphylococcus aureus in the dairy products. Therefore, this study aimed to study variation in bacterial isolation percentage and the bacterial counts in raw milk and locally produced soft cheese in local markets in Baghdad. A total of 150 samples of raw milk and local soft cheese (75 for each) were collected from different regions of Baghdad city from October 2020 to July 2021 to study the evaluation of bacterial contamination. The isolation percentage of total coliform, Fecal coliform, Escherichia coli and Staphylococcus aureus in the raw milk were 82, 69, 54 and 42%, respectively. While in the soft cheese, the isolation percentage for coliform, Fecal coliform, Escherichia coli and Staphylococcus aureus were 90, 74, 60 and 45%, respectively. Furthermore, high percentages of bacterial isolation were recorded during summer. The recorded data showed significant (P<0.05) variation for both raw and soft cheese according to months, and soft cheese had a higher isolation percentage than the raw milk samples. The average values of bacterial count values that were isolated from October to February in the raw milk of the total coliform, fecal coliform, E. coli and Staph aureus were 5.57, 4.25, 3.77 and 2.94 cfu log₁₀/mL respectively, which were recorded during the cold months. While the recording of the average values from March to July as hot months were 6.02, 5.02, 5.22 and 3.23 CFU log₁₀/mL, respectively. The average bacterial values in the soft cheese were 6.02, 5.03, 4.97 and 3.67cfu log₁₀ /g, respectively, from October to February and were significantly (P<0.05) less than the summer from March to July, which recorded 7.17, 6.32, 5.01 and 4.15cfu log₁₀/g respectively. The high contamination found in the soft cheese and during hot months compared with raw milk and cold months, respectively, is a sign of unsanitary manufacturing conditions such as post-process contamination, high temperature in summer, and lack of refrigeration during long-distance transportation.

Keywords: Coliform; Contamination; Raw Milk; Soft Cheese; Variation; Staphaureus.