**4.2.6 Domestic commercial pasteurized milk**

Mean total bacterial counts ranged from 6.60 to 7.54 log10 cfu/ml of domestic pasteurized milk collected from different kiosks and supermarkets in Addis Ababa with the average value being 7.28 log10 cfu/ml (Table 5). Mean counts of coliform bacteria and *Enterobacteriaceae* were 2.87 and 3.69 log10 cfu/ml, respectively. These values are much higher than the acceptable values. As presented in microbiological safety limits for major milk products in community legislation in force by the European Commission, the maximum limit for total bacterial and coliform counts in pasteurized milk intended for drinking is 5x105 and 5 cfu/ml, respectively, while *Enterobacteriaceae* count should be <1 cfu/ml and pathogenic microorganisms should not be detected in 25 ml of the product (Council Directives 92/46 EEC, 1992).

The pasteurized milk samples considered in the present study were between 5 to 2 days before the expiry date as indicated on the packaging materials. Although, the high total

Mean TBC ranged from 6.46 cfu/g in *Ayib* samples collected from Arsi and Selale area to 7.87 cfu/g in samples from Sululta with the overall mean being 7.01 cfu/g. Average *Enterobacteriaceae* and coliform counts were greater than 4 cfu/g of *Ayib* sampled from all study sites. Mean yeast and mould counts observed in the current study exceeded 8 cfu/g of

*Ayib* samples contained high numbers of mesophilic bacteria, *Enterococci*, and yeasts (Ashenafi, 2002). The author also reported aerobic mesophilic bacterial counts of over 108 cfu/g for more than 90% of the samples collected in Southern Ethiopia. Works undertaken to identify bacterial species in *ayib* samples reported *Klebsiella pneumoniae*, *Klebsiella oxytoca*, *Enterobacter cloacae*

Several earlier works carried out in different parts of the country reported coliform counts of *ayib* samples that ranged between 2 log cfu/gm (Ashenafi, 2002, 2006) and 5.68 log cfu/gm (Yilma *et al.*, 2005) with differences being a function of source of samples and handling conditions. Coliform counts varied among samples collected from different producers where samples from research centers had lower coliform counts (4.85 log cfu/gm) as compared to samples from large-scale (5.68 log cfu/gm) and small-scale (5.48 log cfu/gm) farms showing variations in the hygienic conditions practiced among the different producers (Yilma *et al.,* 2005). However, in all cases values are higher than the acceptable level of <10 cfu/gm (Mostert and Jooste, 2002) indicating the poor hygienic conditions

*Ayib* samples collected from an open market in Awassa showed high numbers of mesophilic bacteria, enterococci and yeasts (Table 19). More than 90% of the samples had aerobic mesophilic counts of ≥ 108 cfu/g while more than 75% of the samples had yeast counts of ≥ 107 cfu/g, and over 85% contained *Enterococci* in numbers of ≥ 107 cfu/g. The majority of the samples had mould and lactic acid bacteria counts of 105 cfu/g or higher, spore-formers of about 104 and psychrotrophs of about 106 cfu/g. Over 32% had coliform counts of more than 102/g and about 27% contained fecal coliform loads of more than 102/g. *Bacillus cereus* and *Staphylococcus aureus* were isolated in 63% and 23% of the samples, respectively, but at low

Mean total bacterial counts ranged from 6.60 to 7.54 log10 cfu/ml of domestic pasteurized milk collected from different kiosks and supermarkets in Addis Ababa with the average value being 7.28 log10 cfu/ml (Table 5). Mean counts of coliform bacteria and *Enterobacteriaceae* were 2.87 and 3.69 log10 cfu/ml, respectively. These values are much higher than the acceptable values. As presented in microbiological safety limits for major milk products in community legislation in force by the European Commission, the maximum limit for total bacterial and coliform counts in pasteurized milk intended for drinking is 5x105 and 5 cfu/ml, respectively, while *Enterobacteriaceae* count should be <1 cfu/ml and pathogenic microorganisms should not be

The pasteurized milk samples considered in the present study were between 5 to 2 days before the expiry date as indicated on the packaging materials. Although, the high total

(Yilma *et al.,* 2007b), *Staphylococcus aureus* and *Bacillus cereus* (Ashenafi, 2002).

**4.2.5 Ayib – Ethiopian cottage cheese** 

*Ayib* sampled from all the sites considered.

practiced during processing and handling.

numbers (102 to 103 cfu/g) (Ashenafi, 1990).

**4.2.6 Domestic commercial pasteurized milk** 

detected in 25 ml of the product (Council Directives 92/46 EEC, 1992).

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 or thermophilic.


\*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 Forming Units per millilitre

Table 5. Microbial quality of domestic commercial pasteurized milk sampled from different kiosks and supermarkets in Addis Ababa
