**4.2.4 Arera – Defatted sour milk**

Average counts of total bacteria, *Enterobacteriaceae* and coliforms were greater than 9, 4.7 and 4.2 cfu/ml, respectively of *Arera* sampled from all study sites both of which are higher than the acceptable value of <10 cfu/gm (Mostert and Jooste, 2002). Traditionally produced *Arera* sampled from Wollayta area had total bacterial count of about 9 log cfu/ml (Nebiyu, 2008). The same author also reported coliform count of 4.86 log cfu/ml. Different species of bacteria were identified in *Arera* samples collected during both dry and wet seasons, which include: *Klebsiella pneumoniae, Klebsiella oxytoca, Enterobacter cloacae, Enterobacter sakazakii, Esherichia coli* and some species of *Salmonella* (Yilma *et al.*, 2007a).

Microbial Properties of Ethiopian Marketed Milk and Milk Products and

or thermophilic.

Forming Units per millilitre

kiosks and supermarkets in Addis Ababa

**5. Critical control points in the milk chain** 

Associated Critical Points of Contamination: An Epidemiological Perspective 313

bacterial count observed in the current study can partly be attributed by lactic acid bacteria, which can be explained by the low mean pH value of 5.87, the higher counts of coliform bacteria and *Enterobacteriaceae* imply that there was a problem either in the pasteurization process or there occurred post pasteurization contamination during packaging. Protection from post-pasteurization contamination before the milk product is packaged is a critical factor in achieving a safe food. Ingredients added after pasteurization of the milk portion of the food can be a source of pathogens. The control of potential sources of contamination can be addressed by following production practices based on Good Manufacturing Practices.

Pasteurized milk had mesophilic aerobic counts of 7 x 105 cfu/ml as it left the pasteurizing unit (Mahari and Gashe, 1990). According to the same source, psychrophilic, thermoduric and thermophilic organisms constituted 53.0, 39.5 and 7.5%, respectively and the isolates belonged mostly to the genera *Bacillus, Streptococcus, Lactobacillus, Arthrobacter, Alcaligenes, Aeromonas* and *Pseudomonas*. *Cocci* were more predominant than rod-shaped bacteria and of the rod-shaped bacteria 73% were gram-negative. As indicated by the same authors, utensils holding the raw and pasteurized milk and plastic sheets used for bagging the pasteurized milk were reported to contribute for the high bacterial count, which were either thermoduric

**Pasteurized milk sample\* No. of obs. Count, Log10 cfu/ml** 

A 4 7.28 3.18 3.58 B 4 6.60 3.28 3.94 C 4 7.47 3.26 4.26 D 4 7.37 2.34 3.63 E 4 7.54 2.77 3.68 F 4 7.42 2.40 3.05 Overall mean 24 7.28 2.87 3.69 \*Different letters represent different brands of pasteurized milk marketed in Addis Ababa; TBC: Total Bacterial Count; CC: Coliform Count; EntC: *Enterobacteriaceae* Count; cfu/ml: Colony

Table 5. Microbial quality of domestic commercial pasteurized milk sampled from different

As with hygiene and food safety, the issue of quality has been growing prominently in recent years and the optimum approach to these two areas is remarkably similar. Providing quality assured products to the consumer has traditionally relied on quality control of finished products, that is, a set of procedures to test and analyze the product to ensure it conforms to the required specification. This approach has drawbacks that include incidents of food poisoning in spite of quality control procedures, less effective as microorganisms are not evenly distributed in products, and high cost of rejected products as the quality control is based solely on finished product testing. This is one reason why, developments in quality management have focused on the prevention of defects in the first place (through effective design and hazard elimination) rather than trying to measure defects once the product has been manufactured. Applying this approach to hygiene has led to the development of preventive

**TBC CC EntC** 
