PESAZURIN AND METHYLENE BLUE AS INDICATORS OF THE HYGIENIC QUALITY OF RAW MILK

SUMMARYOne hundred and twenty-nine samples of fresh cream collected in Worcestershire were examined bacteriologically. Sixty (46·5 %) creams had counts of over 100,000 bacteria/ml. The bacteria present were of many varieties, the commonest being Bacillus spp. (aerobic spore formers), Gram-negative bacilli, staphylococci and micrococci. Since most of the creams had been either pasteurized as cream or manufactured from pasteurized milk it was thought that the many bacteria were present because of contamination after pasteurization due to three main causes; unsatisfactory or unhygienic premises, unsuitable equipment, manual handling during the filling and capping process.The methylene blue test results related well with bacterial counts but there were seven (5·4 %) anomalous results. Although the methylene blue reduction test therefore could serve as a simple and reasonable guide to the hygienic quality of fresh cream, 5·4 % of anomalous results would perhaps make it unsuitable as a statutory test.We thank Mr R. Colenso, M.A.P.H.E., M.A.P.H.I., Chief Public Health Inspector, and Mr H. Beckett, Milk Sampling Officer of the Worcestershire County Council, for arranging the supply of samples.

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Organic versus Conventional Raw Cow Milk as Material for Processing

Animals ◽

10.3390/ani11102760 ◽

2021 ◽

Vol 11 (10) ◽

pp. 2760

Author(s):

Aneta Brodziak ◽

Joanna Wajs ◽

Maria Zuba-Ciszewska ◽

Jolanta Król ◽

Magdalena Stobiecka ◽

...

Keyword(s):

Fatty Acids ◽

Dairy Products ◽

Whey Proteins ◽

Raw Milk ◽

Cow Milk ◽

Animal Origin ◽

Organic Milk ◽

Hygienic Quality ◽

Health Promoting

Milk, as one of the basic raw materials of animal origin, must be of adequate hygienic and physicochemical quality for processing. The aim of the article was to compare the quality of raw milk from three production systems, intensive, traditional (together referred to as conventional), and organic, as material for processing, as well as the quality of products made from it. Particular attention was focused on hygienic quality (somatic cell count and total bacterial count), physical characteristics (acidity), basic nutritional value (content of dry matter, total protein, casein, fat, and lactose), content of health-promoting substances (whey proteins, fatty acids, vitamins, and minerals), and technological parameters (rennet clotting time, heat stability, and protein-to-fat ratio). Research assessing the quality of organic milk and dairy products is significantly less extensive (if available at all) than for milk from conventional production (intensive and traditional). The available reports indicate that raw milk from organic farms is more valuable, especially in terms of the content of health-promoting compounds, including vitamins, fatty acids, whey proteins, and minerals. This applies to organic dairy products as well, mainly cheese and yoghurt. This is explained by the fact that organic farming requires that animals are kept in the pasture. However, the hygienic quality of the raw milk, and often the products as well, raises some concerns; for this reason, organic milk producers should be supported in this regard, e.g., through consultancy and training in Good Hygienic Practices. Importantly, milk production in the traditional and organic systems is in line with the concept of the European Green Deal.

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Effect of High Temperature, Short Time (HTST) Pasteurization on Milk Quality Intended for Consumption

Asian Journal of Dairy and Food Research ◽

10.18805/ajdfr.dr-210 ◽

2021 ◽

Author(s):

Aissam Bousbia ◽

Yassine Gueroui ◽

Sofiane Boudalia ◽

Mhamed Benada ◽

Mabrouk Chemmam

Keyword(s):

Heat Treatment ◽

Raw Milk ◽

Resistant Bacteria ◽

Hygienic Quality ◽

High Temperature Short Time ◽

Aerobic Flora ◽

Short Time ◽

Sensory Profiles ◽

Reconstituted Milk

Background: In the dairy industry, hygienic quality and safety of milk and dairy products are very important for human health.Methods: The samples taken at the inlet and outlet of the HTST pasteurization process were subjected to physicochemical, bacteriological and sensory analysis.Result: showed that pasteurization has not only been beneficial, as in the case of the hygienic quality of raw milk, where the number of the Total Mesophilic Aerobic Flora dropped by 94% after heat treatment, to reach an average of 5.62 × 104 CFU ml-1 of the thermo-resistant bacteria. Heat treatment resulted in a decrease of protein and lactose values for both types of milk. In fact, this loss is more marked in raw milk than in reconstituted milk (4% against 1.8%, respectively, p less than 0.05). Wetting was more marked after pasteurization for raw milk (0.102°C) compared to reconstituted milk (0.014°C). Sensory profiles were modified in both milk types, with a significant decrease in color, viscosity and flavor descriptors and a significant increase in the intensity of smell and taste (p less than 0.05).

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The Effect of Raw Milk Hygienic Quality on the Quality of Dairy Products

Milk ◽

10.1007/978-94-017-5571-9_95 ◽

1987 ◽

pp. 845-853

Author(s):

D. I. Jervis

Keyword(s):

Dairy Products ◽

Raw Milk ◽

Hygienic Quality

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Nutritional and Hygienic Quality of Raw Milk in the Mid-Northern Region of Algeria: Correlations and Risk Factors

The Scientific World JOURNAL ◽

10.1155/2014/131593 ◽

2014 ◽

Vol 2014 ◽

pp. 1-7

Author(s):

Soumeya Adjlane-Kaouche ◽

Rafik Benhacine ◽

Faiçal Ghozlane ◽

Abderrahmane Mati

Keyword(s):

Risk Factors ◽

Methylene Blue ◽

Significant Variation ◽

Raw Milk ◽

Northern Region ◽

Aerobic Bacteria ◽

Antibiotic Residues ◽

Average Temperature ◽

Almost All

This paper aims to study the overall quality of raw milk in the mid-northern region of Algeria. The analysis results showed a decrease in the average temperature for the delivery of 1,54°C withP<0.001. However, no significant variation (P>0.05) was observed in almost all the physical and nutritional parameters studied (pH, fat content, and protein content) between M1 and M2. The average contamination by total mesophilic aerobic bacteria (TMAB), coliforms, yeasts, molds, and different pathogens in samples taken at M1 showed significant changes at M2. This was confirmed by the decrease of reduction time of methylene blue (RTMB), about 54%. The variation was described as follows: (P>0.05) for yeasts and (P<0.05) for molds in M1 and M2, (P<0.05) for TMAB in M1, and (P<0.001) for TC, FC, and TMAB in M2. The analysis for the detection ofSalmonellaspp. showed no contamination in all samples tested, while antibiotic residues were detected in 35% of milks delivered. In conclusion, several risk factors have been identified in this study, namely, the effect of the season and the distance between the farm and the dairy unit.

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THE BEHAVIOUR OF RESAZURIN IN MILK

Canadian Journal of Research ◽

10.1139/cjr42c-031 ◽

1942 ◽

Vol 20c (6) ◽

pp. 336-346 ◽

Cited By ~ 1

Author(s):

C. K. Johns

Keyword(s):

Methylene Blue ◽

Comprehensive Index ◽

Hygienic Quality ◽

Metabolic Activities ◽

Sufficient Magnitude ◽

Quality Of Milk ◽

Interpretation Of Results

The view that resazurin is not a satisfactory substitute for methylene blue in assessing the hygienic quality of milk has been examined.Resazurin is equally as sensitive as methylene blue to the metabolic activities of bacteria in milk. It is decidedly more sensitive to the presence of non-bacterial factors in abnormal milks (mastitis, late lactation, etc.) and therefore furnishes a more comprehensive index of the true quality of the milk.Potentiometric studies with a wide variety of milks have failed to support the view that resazurin exerts such a strong poising action in market milks as to complicate the test or interfere with the interpretation of results. No evidence was obtained in support of the claim that differences in poising properties of different milks are of sufficient magnitude to affect the results of the test.

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Data supporting the quality of sheep milk for processing

Acta Agraria Debreceniensis ◽

10.34101/actaagrar/2/3616 ◽

2001 ◽

pp. 67-73

Author(s):

József Csanádi ◽

András Jávor ◽

József Fenyvessy

Keyword(s):

Raw Milk ◽

Medium Size ◽

Lactation Period ◽

Slow Cooling ◽

Physiological Factors ◽

Hygienic Quality ◽

Ewe's Milk ◽

Quality Of Milk ◽

Long Storage

Although the volume of ingredients in ewe’s milk is substantially higher than in cow’s milk, its hygienic quality is lower. The weak quality of raw ewe’s milk limits the possibilities of processing and results in bad quality products. In our investigation we analysed the state of ewe’s milk processing at a typical medium size dairy firm. We investigated the collection, the amount and the quality of milk and the level of ingredients in milk throughout the purchasing period (lactation period).The purchasing of ewe’s milk was limited to 5 months (from April to September). Although meat (lamb) provides the major source of income to sheep breeders the extension of the period of ewe’s milk production can be beneficial to shepherds and dairy firms. The amount of ewe’s milk ingredients found corresponded to published findings. However, the hygienic quality of ewe’s milk was varied greatly in the different milk samples and these deviations meant bad quality on average. Physiological factors, the circumstances of sheep breeding and milking, the slow cooling of the milk, the little amount of daily milk and the long storage before transportation to the dairy firm together cause poor hygienic quality. The main problem is the long storage time of milk, but our results raise the question of reconsidering the quality classes. Investigating the effect of the hygienic quality of raw milk on product quality, we can get correct data that can be really authoritative.

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