scholarly journals Nucleic Acid-Based Methods to Identify, Detect and Type Pathogenic Bacteria Occurring in Milk and Dairy Products

Author(s):  
Vincenzina Fusco ◽  
Grazia Marina
2021 ◽  
Vol 6 (3) ◽  
pp. 353-359
Author(s):  
T. V. Sclyar ◽  
◽  
O. O. Pospielova ◽  
N. V. Cherevach ◽  
O. A. Dregval ◽  
...  

Milk and dairy products are an excellent environment for the development of microorganisms that can cause various defects in the products and in some cases lead to human disease. Under the action of bacteria, yeast, molds, if the rules of procurement are not observed, transportation, storage and sale of dairy products deteriorate rapidly, lose nutritional value, become dangerous for consumption. The purpose of the research was the monitoring of quality of dairy products sold in the trade network of Dnipro according to the sanitary-microbiological indicators. Material and methods. We analyzed 79 samples of milk and dairy products of different trade mark. 56 (64,5%) samples were not standard indexes from which 10 samples of pasteurized milk, 9 samples of yogurt, 6 samples of kefir, 8 samples of sweet-cream butter, 7 samples of cottage cheese, 6 samples of sour cream and 5 samples fermented baked milk. Results and discussion. The obtained results showed that 19 samples of dairy products contained less viable bacteria, than it was indicated according to sanitary and microbiological indexes. There was the greatest number of nonstandard products among samples of yogurt (6) and cottage cheese (4). The study showed that out of 56 analyzed dairy products 13 contained yeast in an amount that exceeds the standard rates. The largest number of non-standard samples (5) was found in yogurt. In 12 samples the maximum number of molds was exceeded. The highest number of molds contaminated product samples was found among cottage cheese (4), kefir (3) and butter (3). In the presence of sanitary-indicative microorganisms we did not meet the requirements of the normative indicators of 35 samples of dairy products, which was 44.3% of the total number of analyzed samples. Escherichia coli bacteria were found in samples of all types of dairy products. The most contaminated were samples of milk (6 samples), kefir (6 samples) and yogurt (5 samples). Conclusion. Out of 7 types studied most dairy products contaminated by all indicators were yoghurt and cottage cheese. Staphylicoccus aureus was detected in 2 samples of lactic acid products. Pathogenic bacteria, including representatives of the genus Salmonella and Listeria monocytogenes, were not found in none of 79 samples of seven types of dairy products


2013 ◽  
Vol 22 (1) ◽  
pp. 16-34 ◽  
Author(s):  
Frank Driehuis

Silage contains a number of potential hazards to the safety and quality of milk and dairy products. This paper reviews the present knowledge about silage as a source of (1) spores of anaerobic spore-formers (Clostridium species) and aerobic spore-formers (mainly Bacillus and Paenibacillus species), (2) the zoonotic pathogenic bacteria Listeria monocytogenes and Escherichia coli, and (3) mycotoxins. A distinction is made between field-derived mycotoxins, i.e. mycotoxins that are formed during growth of crops in the field, and ensilage-derived mycotoxins, i.e. mycotoxins that are formed after ensiling. The routes of transmission of these hazards from feed to milk, the effect of pasteurization of milk, and reduction strategies are discussed. Aerobic deterioration of silages is a major factor influencing levels of spores of both aerobic and anaerobic spore-formers, L. monocytogenes, and certain mycotoxins.


Author(s):  
Minh Huyen Nguyen Thi ◽  
Hoa Tran Thi ◽  
Tuyet Lan Ninh Thi ◽  
Hien Tran Thi ◽  
◽  
...  

Milk and dairy products from dairy farms around Hanoi greatly contribute to the consumed milk quantity in Hanoi. The use of fresh milk or pasteurized milk becomes more and more popular in the daily life of local people. Milk and dairy products were widely sold in numerous stores, particularly in Xuan Mai, Ba Vi, Phu Dong and Gia Lam. However, there have not yet been any studies to assess the pathogenic bacterial contamination of these products. In our study, 49 samples including 23 raw milk samples, 12 pasteurized milk samples, and 14 yogurt samples were collected in order to examine the presence of food­born pathogenic bacteria such as Listeria monocytogenes, Staphylococcus aureus, Salmonella spp. using PCR method. This fast and accurate method works based on the specific amplification of tested bacterial DNA. The results showed that one of the samples may contain Staphylococcus aureus while another may be contaminated with Listeria monocytogenes. None of the samples was contaminated with Salmonella spp. The results were confirmed by gene sequencing.


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