Abstract
The research project was carried out at the Dairy Technology and Microbiology Laboratory of the Department of Dairy Science, Bangladesh Agricultural University, Mymensingh to evaluate the quality of market milk collected from some selected areas of Bangladesh and at the same time to monitor the feasibility of using some traditional rural technology used by farmers' to improve the storage life of milk. Attempts were also made to find out low cost milk preservation technique which could be used by village farmers' without having any risk of health hazards. To achieve the objectives of the project a series of experiments were conducted. Out of them two were on milk quality and others four were on milk preservation by various means. First experiment was carried out in some selected areas of Mymensingh district and the second experiment was carried out in Northern part of the country (Sirajgonj and Pabna district). In both experiments, milk samples were collected from different sources like city centre, local markets, farmers' house and organized dairy farm etc. to evaluate the quality of milk. Some physical, chemical and microbiological tests were conducted to evaluate the quality of milk. From the result of both experiments it was found that wide variations were found within different samples regarding quality. On the basis of physical and chemical parameters it was found that milk produced at Bangladesh Agricultural University Dairy Farm was superior to other milk samples. But microbiological parameters indicated that total viable bacterial count and coliform bacterial count for all samples were higher than normal value indicating that proper hygienic measures were not taken during milking, handling and transportation of milk. Third experiment was conducted to see the feasibility of using sodium bicarbonate on the keeping quality of milk. In this experiment fresh milk samples were preserved by adding 0.10, 0.15 and 0.20 per cent sodium bicarbonate on the basis of weight of milk samples. Shelf-life of the samples were judged with the help of acidity and COB test. It was found that at room temperature 30–32ºC control milk sample spoiled at 12th hour but 0.10, 0.15 and 0.20 per cent sodium bicarbonate added samples spoiled at 13, 14 and 16th hour respectively indicating that this chemical could be used for short time preservation of milk. The fourth experiment was carried out to monitor the effects of containers on shelf-life of milk. Fresh whole milk samples were kept at room temperature in six different types of containers namely stainless steel, aluminium, glass, plastic, tin and earthen containers. It was found that stainless steel and aluminium containers were good for storage of milk followed by glass and plastic containers. In tin and earthen containers milk sample spoiled rapidly. In fifth experiment attempts were made to evaluate the effectiveness of adding banana leaf on shelf-life of milk. But it was found that banana leaf could help to prevent agitation but could not improve the storage life of milk. Sixth experiment was carried out to see whether the shelf-life of whole milk samples could be increased for a while by adding fresh water. In this experiment 10, 20 and 30 per cent of fresh cold water was added with milk samples and found that by adding 20 to 30 per cent water with milk shelf-life could be extended 3 to 4 hours more than the normal shelf-life of milk.