Pasteurised milk in Bangladesh markets may be unsafe for direct consumption

Over 75 percent of commercially available pasteurised milk in Bangladesh may be unsafe for direct consumption due to bacterial contamination, indicates an icddr,b study.

Photo: International Food Policy Research Institute (IFPRI). CC BY-NC-ND 2.0

Pasteurisation is meant to kill pathogenic bacteria in milk, making it safer to consume. The study found around 77 percent of all pasteurised milk samples to contain a high level of total bacterial counts (aerobic plate count), which is beyond the BSTI (Bangladesh Standards and Testing Institution) standards of ≤2.0X104 CFU/ml, according to the findings published in the International Journal of Food Microbiology.

National and international standards have zero tolerance for faecal coliforms in pasteurised milk.

icddr,b associate scientist Dr Mohammad Aminul Islam, head of the Food Microbiology Laboratory and principal investigator of the study observes that raw or pasteurised milk available in the market - the primary source of nutrition for many children – should not be consumed without thorough boiling. “However, samples from UHT milk were found safe for direct consumption,” he adds.

The study assessed the dairy value chain for the presence of bacteria in milk at different stages. “Our studies show that several factors are involved in the contamination of milk at the primary producers’ level including the breed of the cow, volume of milk produced by the cow, the time of milking, and farmers’ hand washing practices,” adds Dr Islam.

“We recommend that Bangladesh’s dairy companies should have end-to-end compliance of hygienic milking practices, collection and delivery, preservation and pasteurisation practices to ensure safe and nutritious milk for all. Maintenance of seamless cold chain throughout the distribution channel of pasteurised milk from factory to consumer’s table is also critical for ensuring safe milk for consumption,” mentioned Dr Islam.

The research was funded by CARE Bangladesh through its ‘Strengthening the Dairy Value Chain (SDVC)’ project and was conducted in 18 upazilas of Bogra, Gaibandadha, Nilphamari, Dinajpur, Joypurhat, Rangpur and Sirajgonj.


What the assessment found

With the aim to assess the microbiological quality of milk at different stages of the dairy value chain, 438 raw milk samples were collected from milk producers, collectors, chilling plants, local restaurants in the northern part of Bangladesh. Additionally, 95 samples were collected from commercially processed milk found on the shelves of local retail stores in Dhaka and Bogra.

At every stage of the dairy value chain from the farm to store, milk was found to be highly contaminated with bacteria above national and international standards. However, this can only be dangerous if consumed ‘raw’ (unboiled), which is often practiced in Bangladesh.

Photo: gordontour. CC BY-NC-ND 2.0

The study finds that at the primary producers level, 72 percent and 57 percent milk samples were contaminated with coliform (≥ 100 CFU/ml) and faecal coliform (≥ 100 CFU/ml) bacteria, respectively and 11 percentof samples were contaminated with high number of E. coli (≥ 100 CFU/ml).

The faecal coliform bacteria is considered as a hygiene indicator and presence of these bacteria in the milk indicates that milk has been contaminated with pathogens or disease producing bacteria or viruses, which can also exist in faeces of warm blooded animals, role of milking animal or the farmers to blame.

At the collection points, samples were found to be contaminated with a high number of coliform bacteria (≥ 100 CFU/ml) and faecal contamination (91 percent) while more than 40 percent of samples had a high E. coli count.

At the chilling plants, collected samples were found to be contaminated even at a higher rate than that of collection points. Samples from all 15 chilling plants distributed in five districts were contaminated with high number of coliform as well as faecal coliform. E. coli was found in samples from all chilling points while 67 percent of samples were contaminated with high level of E. coli.

Presences of some other bacteria such as B. cereus, staphylococci were also found in the samples but within normal limit. Bacterial counts in milk gradually increase from producers’ level to the chilling plants and to the consumers’ levels (e.g. local restaurants).

However, this study did not test the milk for chemical contamination or adulteration.