scholarly journals The freezing point of raw and heat treated sheep milk and its variation during lactation

2013 ◽  
Vol 82 (2) ◽  
pp. 187-190
Author(s):  
Bohumíra Janštová ◽  
Pavlína Navrátilová ◽  
Michaela Králová ◽  
Lenka Vorlová
Keyword(s):  
Freezing Point ◽  
Chemical Properties ◽  
Raw Milk ◽  
Important Indicator ◽  
Pasteurized Milk ◽  
Milk Samples ◽  
Sheep Milk ◽  
Physico Chemical ◽  
Heat Treated ◽  
Time Specific

The freezing point of milk is an important indicator of the adulteration of the milk with water, but heat treatment may also affect its value. The aim of this study was determine freezing point of raw and heat treated sheep milk and its variation during lactation. The freezing point was determined in 42 bulk tank raw sheep milk samples and 42 pasteurized milk samples collected during lactation of sheep at one ecofarm in Moravian Walachia (Valašsko in the Czech Republic). The freezing point was determined in accordance with the standard ČSN 57 0538 using a thermistor cryoscope. The average freezing point of raw milk was -0.617 ± 0.052 °C, with a range from -0.560 to -0.875 °C. The freezing point was lower in the first months of lactation and increased at the end of lactation. The freezing point correlated (r = 0.8967) with the content of total non-fat solids. The average freezing point of sheep milk pasteurized at 65 °C for 30 min was -0.614 ± 0.053 °C, with a range from -0.564 to -0.702 °C. The median of freezing point differences between raw and pasteurized milk was 0.004 °C. Our study extends data about physico-chemical properties of sheep milk and registers for the first time specific changes in the freezing point value of sheep milk by heating.

scholarly journals The Effect of Lactation Number on Physico-Chemical and Microbiological Parameters of Milk from Small and Medium Bovine Farms located in Transilvania Region

2020 ◽  
Vol 77 (2) ◽  
pp. 36
Author(s):  
Ioan HAN ◽  
Otilia BOBIŞ ◽  
Liviu Alexandru MĂRGHITAŞ
Keyword(s):  
Freezing Point ◽  
Biological Fluid ◽  
Microbiological Quality ◽  
Chemical Properties ◽  
Raw Milk ◽  
Raw Material ◽  
Fat Percentage ◽  
Mean Values ◽  
Normal Limits ◽  
Physico Chemical

Milk is a biological fluid where fats are distributed in microglobules (2-10 million/cm3), in an aqueous solution of proteins, carbohydrates and other substances. The main physico-chemical properties of milk are: density, viscosity, specific heat, boiling point, freezing point, pH and total acidity. Microbiological quality is represented by the presence or absence of pathogens or alterations, which can contaminate milk as a raw material. The comparative nutritional and microbiological quality of milk from three counties, from Transilvania Region, were fat percentage, total protein, casein content, lactose, pH, urea, total germ count (TGC) and somatic cell count (SCC). The best percentages of fat were obtained in Bihor County, with mean values of all lactations of 4.00%. This was followed by Hunedoara County with 3.97% and Alba County with 3.95%. The highest protein percentages were obtained in samples collected in Bihor County, with mean values of 3.57%, followed by Hunedoara County with 3.52% and Alba County with 3.51%. Most physicochemical indices fall within the normal limits, unanimously accepted by existing standards, but microbiological indices in some cases do not meet the requirements for the admission of raw milk.

scholarly journals The Physicochemical Quality of Traditional Burduf Cheese

2013 ◽  
Vol 70 (2) ◽  
pp. 137
Author(s):  
Carmen Pop ◽  
Cristina Anamaria Semeniuc ◽  
Sorin Apostu ◽  
Ancuţa Mihaela Rotar
Keyword(s):  
Quality Control ◽  
Raw Milk ◽  
Cow Milk ◽  
Chemical Parameters ◽  
Physicochemical Quality ◽  
Milk Samples ◽  
Sheep Milk ◽  
Physico Chemical ◽  
Different Types

The aim of this study is the assessmentof the quality control of raw milk and traditional burduf cheese obtained fromcow milk mixed with 10% sheep milk. Appreciation of the integrity and freshness assessmentof milk (cow and sheep) was tested by physico-chemical analysis.On theshelf-live were determined the physico-chemical parameters in cheese samples. Theantibiotics residues were tested of the milk samples with portable analyser,model Rosa Charm Reader. Theresults of physico-chemical determinations for the milk and cheese samples werewithin the maximum permissible by data legislation. Regardingthe content of antibiotics, the results were negative both for cow milk and forsheep milk. The sensorycharacteristics of burduf cheese are influenced by the different types of milk.

ANALYSIS OF SOME PHYSICAL AND CHEMICAL PROPERTIES OF YOGHURT WITH BIFIDOBACTERIUM IN BELARUS.

2020 ◽  
Vol 14 (1(51)) ◽  
pp. 79-92
Author(s):  
I. V. Podorozhniaya ◽  
S. S. Vetokhin
Keyword(s):  
Water Activity ◽  
Freezing Point ◽  
Chemical Properties ◽  
Titratable Acidity ◽  
Raw Milk ◽  
Physical And Chemical Properties ◽  
Nonfat Milk ◽  
Milk Solids ◽  
Physical And Chemical ◽  
And Chemical Properties

The values of freezing point, titratable and active acidities, conductivity, water activity, humidity, nonfat milk solids the of samples of market bioyoghurt were analyzed. They significantly differ from the same row milk indicators. So, they demonstrated lower values of freezing point, active acidity, water activity, humidity, and increased values of titratable acidity and conductivity, and nonfat milk solids. A large dispersion of the studied products’ properties was found for each manufacturer production as well as between producers. Yoghurts with Bifidobacterium that were produced at the Brest region had the highest values of рН, nonfat milk solids and lowest values of freezing point and humidity. This fact evidences the manufacturer has a well-established technological process for the production of bioyogurt and traceability of raw milk supply. The boundaries of the confidence intervals of physical and chemical properties both by individual manufacturers and jointly were determined. A close relationship between conductivity and freezing point in bioyoghurts of some manufacturers has been found. The dynamics of their changes in last years is traced.

Low Incidence of Foodborne Pathogens of Concern in Raw Milk Utilized for Farmstead Cheese Production

2008 ◽  
Vol 71 (8) ◽  
pp. 1580-1589 ◽  
Author(s):  
DENNIS J. D'AMICO ◽  
ERROL GROVES ◽  
CATHERINE W. DONNELLY
Keyword(s):  
Foodborne Pathogens ◽  
Microbiological Quality ◽  
Goat Milk ◽  
Raw Milk ◽  
Pasteurized Milk ◽  
Milk Samples ◽  
Cell Counts ◽  
Standard Plate ◽  
Low Incidence ◽  
Raw Milk Cheese

Overall milk quality and prevalence of four target pathogens in raw milk destined for farmstead cheesemaking was examined. Raw milk samples were collected weekly from June to September 2006 from 11 farmstead cheese operations manufacturing raw milk cheese from cow's, goat's, and sheep's milk. Samples were screened for Listeria monocytogenes, Staphylococcus aureus, Salmonella, and Escherichia coli O157:H7 both quantitatively (direct plating) and qualitatively (PCR). Overall, 96.8% of samples had standard plate counts of <100,000 CFU/ml, 42.7% of which were <1,000 CFU/ml. Although no federal standards exist for coliforms in raw milk, 61% of samples tested conformed to pasteurized milk standards under the U.S. Pasteurized Milk Ordinance (PMO) at <10 CFU/ml. All cow and sheep milk samples and 93.8% of goat milk samples were within the limits dictated by the PMO for somatic cell counts. Of the 11 farms, 8 (73%) produced samples that were positive for S. aureus, which was detected in 34.6% (46 of 133) of milk samples. L. monocytogenes was isolated from three milk samples (2.3%), two of which were from the same farm. E. coli O157:H7 was recovered from one sample of goat's milk for an overall incidence of 0.75%. Salmonella was not recovered from any of the 133 samples. The findings of this study suggest that most raw milk intended for farmstead cheesemaking is of high microbiological quality with a low incidence of pathogens. These data will help inform risk assessments associated with the microbiological safety of farmstead cheeses, particularly those manufactured from raw milk.

Detection of Bacillus cereus Diarrheal Enterotoxin in Raw and Pasteurized Milk

1997 ◽  
Vol 60 (11) ◽  
pp. 1391-1394 ◽  
Author(s):  
JOSEPH A. ODUMERU ◽  
ANN K. TONER ◽  
C. ANNE MUCKLE ◽  
MANSEL W. GRIFFITHS ◽  
JOHN A. LYNCH
Keyword(s):  
Bacillus Cereus ◽  
Raw Milk ◽  
Latex Agglutination ◽  
Moderate Temperature ◽  
Quality Analysis ◽  
Pasteurized Milk ◽  
Milk Samples ◽  
Enterotoxin B ◽  
Culture Supernatants

Raw and pasteurized milk samples submitted for routine quality analysis were screened for the presence of Bacillus cereus diarrheal enterotoxin (BDE) using the TECRA BDE Visual Immunoassay (VIA) kit. BDE was not detected in 298 raw milk samples tested by the TECRA VIA. B. cereus was isolated from 2 of 298 (0.7%) raw milk samples cultured. Culture supernatants from these isolates were positive for BDE in the TECRA VIA but negative in the Reverse Passive Latex Agglutination (RPLA) test for BDE. Forty-three of 112 (38.4%) pasteurized milk samples incubated at 10°C until their expiry dates were positive for BDE by the TECRA VIA. The same number of samples incubated at 4°C had no detectable levels of enterotoxin. B. cereus in the range of 103 to 106 CFU/ml was isolated from all BDE-positive pasteurized milk samples. BDE was detected in the culture supernatants of all the 43 isolates by TECRA VIA and in 30 of these isolates by RPLA. These results demonstrate that moderate temperature abuse of pasteurized milk may allow the growth of B. cereus and BDE production.

scholarly journals Influence of the microbiological quality of raw milk on the shelf life of pasteurized milk

2019 ◽  
Vol 40 (4) ◽  
pp. 1469
Author(s):  
José Carlos Ribeiro Júnior ◽  
Aline Marangon de Oliveira ◽  
Fernando Godoi Silva ◽  
Lorena Natalino Haber Garcia ◽  
Cátia Maria de Oliveira Lobo ◽  
...  
Keyword(s):  
Shelf Life ◽  
Microbiological Quality ◽  
Raw Milk ◽  
Poor Quality ◽  
Pasteurized Milk ◽  
Microbial Counts ◽  
Legal Standards ◽  
Milk Samples ◽  
Brazilian Standard

The dairy industry strives to produce high quality products with high nutritional value as well as to meet the legal standards for longer shelf life. However, these goals are made unfeasible by the poor quality of raw milk produced in some regions of Brazil. Others Brazilian dairy regions, however, already succeed in producing milk with low microbial counts, such as the municipality of Castro, Paraná state, designated as the ‘Brazilian dairy capital’. In order to evaluate the effect of raw milk quality on microbial counts during the shelf life of pasteurized milk, samples were collected from two dairy regions of Paraná: the northern and Castro region, characterized by milk production with high and low microbiological counts, respectively. Samples were experimentally pasteurized and the total microorganism counts were analyzed for 18 days at 7°C, using the Brazilian standard microbiological count limit for pasteurized milk (8 x 104 CFU/mL) as the end of the shelf life. Low microbiological counts in raw milk (Castro) resulted in significantly lower counts shortly after pasteurization and over the entire shelf life, meeting the pasteurized milk standard for 18 days. The temporal evolution in the counts over 18 days for the milks of high and low microbiological count was similar; however, the disparity between the absolute counts between the regions was significant (p < 0.05). Of the milk samples from northern Paraná, four (44.4%) already had counts higher than that of the legislative limit for pasteurized milk immediately after pasteurization. The others (five) reached the maximum microbiological count limit for pasteurized milk on the 6th day after pasteurization. In contrast, the milk from the Castro region remained below the limit throughout the analysis period. Thus, it can be stated that the microbiological quality of raw milk is directly related to the initial count of microorganisms after pasteurization, and that pasteurized milk produced from raw milk with low microbiological counts complies with the Brazilian legislation for 18 days following thermal processing.

scholarly journals Freezing point of raw and heat-treated goat milk

2008 ◽  
Vol 52 (No. 11) ◽  
pp. 394-398 ◽  
Author(s):  
B. Janštová ◽  
M. Dračková ◽  
P. Navrátilová ◽  
L. Hadra ◽  
L. Vorlová
Keyword(s):  
Freezing Point ◽  
Goat Milk ◽  
Raw Milk ◽  
Average Increase ◽  
Heat Treated ◽  
The Mean ◽  
Bulk Tank

The freezing point (FP) was established in 48 bulk tank samples of raw and 48 samples of pasteurized goat milk that were collected in the course of lactation. Alongside, non-fat solids (NFS) content was monitored. Milk freezing point measurements were carried out using the thermistor cryoscope method in compliance with the standard CTS 570538 (1998). The mean freezing point of raw milk was found to be in an interval of –0.5513 ± 0.0046°C, variation ranged from –0.5466°C to –0.5567°C, with higher values in the spring months and a drop at the end of lactation. FP corresponded to the NFS content. The average freezing point of goat milk heat-treated on the farm to the temperature of 72°C over a period of 20 s was –0.5488 ± 0.0046°C, pasteurisation brought an average increase in FP by 0.0025°C.

scholarly journals Effect of Commercial-Scale High-Temperature, Short-Time Pasteurization on the Viability of Mycobacterium paratuberculosis in Naturally Infected Cows' Milk

2002 ◽  
Vol 68 (2) ◽  
pp. 602-607 ◽  
Author(s):  
Irene R. Grant ◽  
Edward I. Hitchings ◽  
Alan McCartney ◽  
Fiona Ferguson ◽  
Michael T. Rowe
Keyword(s):  
High Temperature ◽  
Cetylpyridinium Chloride ◽  
Raw Milk ◽  
Holding Time ◽  
Mycobacterium Paratuberculosis ◽  
Pasteurized Milk ◽  
Milk Samples ◽  
Commercial Scale ◽  
High Temperature Short Time ◽  
Short Time

ABSTRACT Raw cows' milk naturally infected with Mycobacterium paratuberculosis was pasteurized with an APV HXP commercial-scale pasteurizer (capacity 2,000 liters/h) on 12 separate occasions. On each processing occasion, milk was subjected to four different pasteurization treatments, viz., 73�C for 15 s or 25 s with and without prior homogenization (2,500 lb/in2 in two stages), in an APV Manton Gaulin KF6 homogenizer. Raw and pasteurized milk samples were tested for M. paratuberculosis by immunomagnetic separation (IMS)-PCR (to detect the presence of bacteria) and culture after decontamination with 0.75% (wt/vol) cetylpyridinium chloride for 5 h (to confirm bacterial viability). On 10 of the 12 processing occasions, M. paratuberculosis was detectable by IMS-PCR, culture, or both in either raw or pasteurized milk. Overall, viable M. paratuberculosis was cultured from 4 (6.7%) of 60 raw and 10 (6.9%) of 144 pasteurized milk samples. On one processing day, in particular, M. paratuberculosis appeared to have been present in greater abundance in the source raw milk (evidenced by more culture positives and stronger PCR signals), and on this occasion, surviving M. paratuberculosis bacteria were isolated from milk processed by all four heat treatments, i.e., 73�C for 15 and 25 s with and without prior homogenization. On one other occasion, surviving M. paratuberculosis bacteria were isolated from an unhomogenized milk sample that had been heat treated at 73�C for 25 s. Results suggested that homogenization increases the lethality of subsequent heat treatment to some extent with respect to M. paratuberculosis, but the extended 25-s holding time at 73�C was found to be no more effective at killing M. paratuberculosis than the standard 15-s holding time. This study provides clear evidence that M. paratuberculosis bacteria in naturally infected milk are capable of surviving commercial high-temperature, short-time pasteurization if they are present in raw milk in sufficient numbers.

scholarly journals Changes in physico-chemical properties of milk under ultraviolet radiation

2019 ◽  
pp. 161-167
Author(s):  
Vladimir Kharitonov ◽  
Natalia Sherstneva ◽  
Dmitriy Kharitonov ◽  
Elena Yurova ◽  
Vladimir Kurchenko
Keyword(s):  
Vitamin D ◽  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Ultraviolet Radiation ◽  
Acid Composition ◽  
Bacterial Load ◽  
Chemical Properties ◽  
Nonprotein Nitrogen ◽  
Pasteurized Milk ◽  
Physico Chemical

The use of ultraviolet radiation in the treatment of milk and other liquid foods is a very promising field of study since it reduces their bacterial load. It is rarely used to increase the vitamin D content and modify the protein and fatty acid composition of milk. The paper describes how different parameters of ultraviolet radiation influence such characteristics of raw and pasteurized milk as the mass fraction of total protein, nonprotein nitrogen content, active and titratable acidity, general bacterial load (QMA&OAMO), fatty acid composition, and vitamin D content. Low-pressure gas-discharge lamps were used to treat a 400 µm moving layer of milk with ultraviolet radiation. The radiation time, its doses, and the milk flow rate changed in the ranges of 5–25 min, 5.1–102 mJ/cm2, and 0.04453- 0.13359 m3/s, respectively. We identified optimal radiation ranges that lead to both a lower microorganism content and a higher vitamin D content. Our study also determined specific correlations in the mutual changes of the given parameters. The treatment ranges did not produce any significant changes in other physico-chemical properties of milk. We also found that vitamin D was synthesized in raw and pasteurized milk in a similar way. Moreover, there was an insignificant decrease in the vitamin D content in milk treated with ultraviolet radiation during storage for up to 48 hours. On the whole, the results indicate that the treatment of milk with ultraviolet radiation in the dosage range from 5.1 to 102 mJ/cm2 has a complex effect on the total bacterial load (QMA&OAMO) and vitamin D content, whereas it has almost no effect on the protein and fatty acid composition.

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