scholarly journals Incidence of psychrotrophic lipolytic bacteria in cow’s raw milk

2009 ◽  
Vol 54 (No. 2) ◽  
pp. 65-73 ◽  
Author(s):  
R. Cempírková ◽  
M. Mikulová
Keyword(s):  
Storage Time ◽  
Storage Temperature ◽  
Raw Milk ◽  
Culture Methods ◽  
Mean Values ◽  
Psychrotrophic Bacteria ◽  
Milk Samples ◽  
Limit Value ◽  
Significant Difference ◽  
Medium Level

The contamination of bulk samples of cow’s raw milk (<I>n</I> = 491) by psychrotrophic lipolytic bacteria (PLiBC), total count of psychrotrophic bacteria (PBC) and mesophilic bacteria (TBC) was monitored for two years on eight dairy farms and the correlations among these groups of bacteria were analysed. An increase in TBC, PBC and PLiBC and in the values of free fatty acids (FFA) was tested experimentally in three milk samples in relation to time (analyses were done in 24-hour intervals until 96 hours) and storage temperature of milk samples (4; 6.5 and 10°C). Bacterial contamination of milk was determined by culture methods in accordance with IDF standards, the values of FFA were determined by an extraction-titration method. These mean values were determined in the set of samples (<I>n</I> = 491): PLiBC 659 CFU/ml, PBC 2 932 CFU/ml and TBC 18 932 CFU/ml. A high correlation was proved between values of PBC and PLiBC (<I>r</I> = 0.87; <I>P</I> < 0.001) while the correlation between TBC and PBC (<I>r</I> = 0.65; <I>P</I> < 0.001) and between PLiBC and TBC (<I>r</I> = 0.59; <I>P</I> < 0.001) was on a medium level. The proportional index <I>p<sub>I</sub></I> for PLiBC/PBC was 0.20, for PLiBC/TBC 0.03 and for PBC/TBC 0.16. In seasonal dynamics a statistically significant difference (<I>P</I> < 0.001; <I>P</I> < 0.05) between the increased values of TBC in the summer season was proved compared to the winter and spring season. The differences in the seasonal variation of PBC and PLiBC values were not significant. Experimental investigation of an increase in the values of tested parameters showed that at temperatures of milk sample storage 4 and 6.5°C TBC did not exceed the permissible hygienic value (100 000 CFU/ml) even after 96 hours while at 10°C it amounted to 90 000 CFU/ml after 48 hours and the limit for TBC was exceeded several times after 96 hours. PBC, which is not inhibited by cold storage to such a large extent, did not exceed the hygienic limit value for PBC (50 000 CFU/ml) even after 96 hours when milk samples were stored at 4°C, but at 6.5°C after 72 hours and at 10°C already after 48 hours the values 6 and 20 times higher, respectively, than the hygienic limit were recorded. A similar trend was observed in PLiBC, which exceeded the hazardous limit (43 000 CFU/ml) at 6.5°C after 96 hours and at 10°C already after 48 hours whereas at 4°C the limit value was not exceeded even after 96 hours. The content of FFA also increased in relation to the storage time and temperature of milk samples but in comparison with the increase in the tested groups of microorganisms the increase in FFA showed a higher correlation with storage time compared to storage temperature. A medium correlation was calculated between PLiBC and/or PBC and FFA content (<I>r</I> = 0.52; <I>r</I> = 0.57; <I>P</I> < 0.001).

scholarly journals Proteolytic behavior of isolated Pseudomonas spp. from refrigerated raw milk in different concentrations and storage temperatures

2018 ◽  
Vol 39 (1) ◽  
pp. 419
Author(s):  
Ana Cristina Pinesso Ribeiro ◽  
Samera Rafaela Bruzaroski ◽  
Flavia De Almeida Bergonse Pereira ◽  
Fernanda Gonzales Paião ◽  
Regina Celia Poli-Frederico ◽  
...  
Keyword(s):  
Storage Time ◽  
Storage Temperature ◽  
Population Control ◽  
Milk Powder ◽  
Raw Milk ◽  
Initial Population ◽  
Initial Inoculum ◽  
Pseudomonas Spp ◽  
Cell Counts ◽  
Significant Difference

The objective of the work was to evaluate the multiplication capacity and proteolytic activity of different Pseudomonas spp. cell counts inoculated in milk and storaged under different temperature. Strains isolated from refrigerated raw milk (RRM) were confirmed at genus level by Polymerase Chain Reaction (PCR). The Pseudomonas spp. was cultured in cephalothin-sodium fusidate-cetrimide (CFC) agar-base (30?C for 48 h) until it reached 2 log and 6 log CFU mL-1. Three of eight strains confirmed as Pseudomonas spp were inoculated in sterile reconstituted whole milk powder and incubated at 2°C, 4°C, and 8°C for 96 h. Primary proteolysis indices was determined by the Kjeldahl method. When taking into account the effect of storage time in Pseudomonas spp. population, it was found that the initial population (2 log CFU mL-1) showed significant difference in growth rates only from 0 h to 24 h, keeping at the same levels along 96 h. When a higher initial population was incubated (6 log CFU mL-1), it was not observed a significant difference for times tested. Related to the effect of storage time in proteolysis index, it was not observed a significant difference in samples inoculated with 2 and 6 log CFU mL-1 Pseudomonas spp. When we analyzed the influence of storage temperature on the bacterial multiplication, there was a significant difference in the Pseudomonas spp. population only between 2°C and 8°C after 96 h of milk storage with 2 log CFU/mL of initial inoculum. If we consider the temperature effect in the primary proteolysis index, there were significant differences at the inoculum of 2 log CFU mL-1 where the primary proteolysis at 24 h was lower at 2°C than at 8ºC. Low temperatures or short storage time had no influence on Pseudomonas spp. enumeration or in the primary proteolysis index when high initial contaminations are observed. At lower Pseudomonas spp. initial population, the smaller storage time tested influenced the population control, and linked with the reduction in the storage temperature, lower proteolysis index were observed.

scholarly journals Influence of storage temperature on the population of microorganisms in raw sheep milk and its physical-chemical profile

2020 ◽  
Vol 9 (12) ◽  
pp. e27691210796
Author(s):  
Samera Rafaela Bruzaroski ◽  
Raquel Pinheiro de Souza ◽  
Pamela da Silva Pasquim ◽  
Rafael Fagnani ◽  
Elsa Helena Walter de Santana
Keyword(s):  
Storage Time ◽  
Storage Temperature ◽  
Titratable Acidity ◽  
Raw Milk ◽  
Plate Count ◽  
Chemical Profile ◽  
Pseudomonas Spp ◽  
Psychrotrophic Bacteria ◽  
Sheep Milk ◽  
Physical Chemical

The aim of the present study was to evaluate the physical-chemical profile of raw sheep milk and the influence of storage temperature on the population of microorganisms. Sheep milk samples were collected from the milk cans (500 mL/sample) and were evaluated the physical-chemical composition: fat, protein, lactose, ash content, total dry matter (TDM), cryoscopy index (°H), titratable acidity, and somatic cell count (SCC). After the samples were stored at 4°C and 9°C (72 h) and the titratable acidity, the population of the deteriorating microorganisms and quality indicators were determined. PetrifilmTM (3M do Brasil Ltda) were used for the mesophilic aerobic count (37°C/48 h), total coliforms (37°C/24 h), Escherichia coli (37°C/48 h), and enterobacteria (37°C/24 h). For psychrotrophic bacteria, was used Plate Count Agar (7ºC/10 days) and for Pseudomonas spp., CFC-supplemented Pseudomonas agar base (25ºC/48 h). Average values for raw milk were 6.28% fat, 83.46% moisture, 16.52% TDM, 0.92% ash, 5.30% protein, 4.43% lactose, a cryoscopy index of -0.575°H, and SCC of 3.38 x 106 cells/mL. Milk acidity values were higher (0.24 g lactic acid/100 ml) with 72 hours of storage. The higher the temperature and/or storage time, the higher the counts of psychrotrophic, Pseudomonas spp., and enterobacteria, for mesophilic aerobic only the storage time. Refrigeration at 4ºC and a reduction of storage time are important to control the microorganism’s population that compromise the quality, shelf life, and food safety of sheep milk and dairy products.

scholarly journals Composition of raw milk from conventional and organic dairy farming

2016 ◽  
Vol 32 (2) ◽  
pp. 133-143 ◽  
Author(s):  
Denis Kucevic ◽  
Snezana Trivunovic ◽  
Vladan Bogdanovic ◽  
Ksenija Cobanovic ◽  
Dobrila Jankovic ◽  
...  
Keyword(s):  
Statistical Significance ◽  
Raw Milk ◽  
Farming System ◽  
Dairy Farming ◽  
Milk Samples ◽  
High Statistical Significance ◽  
Significant Difference ◽  
Organic Dairy ◽  
One Year ◽  
The Impact

Possible differences between composition of raw milk due to dairy farming system (organic vs conventional) as well as seasonal variations were investigated. The samples were analysed during one year. A total of 6.782 samples of raw milk were collected (4.496 from organic farming). Dairy farms were located in the northern part of Republic of Serbia (Province of Vojvodina). The principle of analysis of raw milk samples was in accordance with the methodology by midinfrared spectrometry and flow cytometry. The fixed effect of system of farming and season (winter, spring, summer and fall) have shown a high statistical significance (P < 0.01) on all examined milk parameters except fat, total solids and somatic cell count, where the impact was slightly lower (P < 0.05). Significant difference wasn't found in number of bacterial colonies (P > 0.05). Composition of milk is also affected by a number of other factors, therefore it is recommended to involve factors such as nutrition of dairy cows, breed and farm management.

Nutrient composition of pastoralist's raw milk of different breeds of cattle in Adamawa and Taraba states, Northeastern Nigeria

2020 ◽  
Vol 47 (2) ◽  
pp. 217-223
Author(s):  
Z. Adamu ◽  
M. B. Ardo ◽  
Y. H. Aliyara
Keyword(s):  
Moisture Content ◽  
Local Governments ◽  
Management Practices ◽  
Raw Milk ◽  
Fat Content ◽  
Ash Content ◽  
Milk Samples ◽  
Moisture Contents ◽  
Significant Difference ◽  
Content Range

This study was carried out to determine the proximate composition of raw milk produced in pastoral settlements. Six hundred pastoralists' raw milk samples were collected from 20 local governments in Adamawa and Taraba states, Nigeria. Milk samples were collected from White Fulani (WF), Red Bororo (RB) and Sokoto Gudali (SG) breeds of cattle and were analyzed for protein, fat, ash and moisture contents. The protein content ranged between 3.62±0.38% -3.95±0.11% in WF, 3.29±0.8% - 3.94±0.10% in RB and 3.31±0.27%- 3.95±0.09% in SG in Adamawa and Taraba states. The fat content ranged between 3.55±0.47% - 3.99±0.03% in WF, 3.98±0.04% - 3.98±0.06% in RB and 3.32±0.20% - 3.45±0.27% in SG. The ash content recorded was between 0.40±0.06% -0.41±0.04% in WF, 0.40±0.06% - 0.43±0.07% in RB and0.39±0.06% - 0.41±0.08% in SG, and the moisture content in Adamawa and Taraba states were between 83.52±2.07% - 84.00±0.57% in WF, 82.28±1.05% - 83.73±0.63% in RB and 82.90±1.48% - 83.56±1.35%in SG. The study from the two states revealed protein value between 3.29± 0.8% - 3.95±0.11%, fat content range of3.32±0.20% - 3.99±0.03%, ash content of between 0.39± 0.06% - 0.43±0.07% and moisture content that ranged between 82.28± 1.05% - 84.00±0.57%. Constituents of milkfrom Taraba state were higher in values than those from Adamawa sate. The statistical analysis of the results at95% confidence level showed significant difference among breeds and states. In comparison, the three breeds that resided in Adamawa state had least values, which could be attributed to herd management practices. This study showed that all the three pastoralists' breeds indicated desirable components in their milk Cross breeding with higher breeds and provision of quality feed and water may lead to better yield in all the breeds in this study.

BACTERIAL COUNTS OF RAW MILK AND FLAVOR OF THE MILK AFTER PASTEURIZATION AND STORAGE

1972 ◽  
Vol 35 (4) ◽  
pp. 203-206 ◽  
Author(s):  
G. B. Patel ◽  
G. Blankenagel
Keyword(s):  
Raw Milk ◽  
Bacterial Counts ◽  
Psychrotrophic Bacteria ◽  
Milk Samples ◽  
Standard Plate ◽  
Plate Counts ◽  
Subsequent Storage ◽  
And Storage ◽  
Common Defect

A total of 216 raw milk samples with a variety of Standard Plate Counts and psychrotrophic bacteria counts were laboratory-pasteurized, stored at 7 C, and then evaluated for flavor after 1 and 2 weeks. Results showed that milk with counts of &gt;1,000,000/ml before heating frequently developed objectionable flavors after pasteurization and subsequent storage. The most common defect was a bitter flavor which appeared within 2 weeks after pasteurization in nearly all samples which as raw milk had counts exceeding 10,000,000/ml. This off-flavor developed in spite of small numbers of organisms in the pasteurized product and in the absence of post-pasteurization contamination.

Rapid Detection of Psychrotrophic Bacteria In Manufacturing Grade Raw Milks

1991 ◽  
Vol 54 (11) ◽  
pp. 861-867 ◽  
Author(s):  
S. R. TATINI ◽  
P. MEKALA ◽  
A. EL-HABAZ ◽  
M. W. GRIFFITHS
Keyword(s):  
Rapid Detection ◽  
Bacterial Count ◽  
Raw Milk ◽  
Plate Count ◽  
Psychrotrophic Bacteria ◽  
Milk Samples ◽  
Microscopic Count ◽  
Direct Epifluorescent Filter Technique ◽  
Native Microflora

Methods to rapidly assess the bacteriological quality of raw milk were investigated. Whereas direct microscopic count, modified psychrotrophic plate count, and direct epifluorescent filter technique (DEFT) did not correlate well with initial psychrotrophic bacterial count of raw milk, improvements were obtained after preincubation of the milk samples. The best preincubation conditions were identified as 30°C for 6 h, 21°C for 10 h, 13°C for 15 h, 13°C for 20 h, or 7°C for 37 h. The “square root” equation was applied to the data, and a model was produced for predicting growth of the native microflora of raw milk. Using this equation, a DEFT count after preincubation of the milk at 21°C for 10 h could accurately predict the initial psychrotroph count and the count after storage of the milk at 6°C for 48 h.

Preliminary Incubation Count as an Index of Raw Milk Microbiological Quality During Storage

1984 ◽  
Vol 47 (3) ◽  
pp. 206-208 ◽  
Author(s):  
J. J. RYAN ◽  
R. H. GOUGH ◽  
C. H. WHITE
Keyword(s):  
Microbiological Quality ◽  
Storage Period ◽  
Raw Milk ◽  
Plate Count ◽  
Bacterial Counts ◽  
Sample Group ◽  
Psychrotrophic Bacteria ◽  
Standard Plate Count ◽  
Milk Samples ◽  
Standard Plate

During a 5-month period, 200 raw milk samples were collected from two Louisiana milk plants. Standard Plate Count (SPC), Psychrotrophic Bacteria Count (PBC), and Proteolytic Count (PC) of each sample were initially determined, then monitored daily during a 5-d storage period at 2.2°C. As hypothesized, all bacterial counts increased during the storage period. The magnitude of the increase in bacterial numbers during storage was further investigated by dividing the milk samples into bacteriologically acceptable and unacceptable groups based on SPC or Preliminary Incubation (PI) count. An SPC of 1.0 × 105/ml and PI counts of 1.0 × 105/ml, 1.5 × 105/ml, 2.3 × 105/ml, and 3.0 × 105/ml were used to repeatedly dichotomize the 200 raw milk samples into two groups. Median SPC, PBC, and PC for each acceptable and unacceptable group were then calculated. Dichotomization based on PI counts yielded acceptable sample groups having consistently lower bacterial counts during storage than did the acceptable sample group, which resulted from the dichotomization based on a SPC of 1.0 × 105/ml. The results of this study indicated that the PI count is of considerable value for raw milk quality control.

Comparison of the Reproducibilities of the Kjeldahl and Dye Binding Methods for Measuring Protein in Milk

1967 ◽  
Vol 50 (3) ◽  
pp. 557-560 ◽  
Author(s):  
J W Sherbon ◽  
Bobbie Hemphill
Keyword(s):  
Raw Milk ◽  
Reaction Flask ◽  
Mean Values ◽  
Milk Samples ◽  
Coefficients Of Variation ◽  
Dye Binding ◽  
Orange G ◽  
Kjeldahl Method ◽  
The Mean

Abstract Protein in milk samples was measured by both the Kjeldahl and Orange G binding methods. Ten samples of pooled raw milk were tested with ten replications of each method. Coefficients of variation were 0.352-3.089% protein for the Kjeldahl method and 0.098-0.661% protein for the dye binding method. The overall means of the two methods were significantly different, but not more than the expected agreement between duplicate Kjeldahl analyses. The position of the reaction flask in the manifold during digestion and distillation affected the Kjeldahl results. One sample of pasteurized-homogenized milk was tested on four successive days. The variation in dye binding results was less than in the Kjeldahl results. The dye binding response decreased each day and the mean values on the first and last days were significantly different

Collaborative Study of the Impedance Method for Examining Raw Milk Samples

1984 ◽  
Vol 47 (9) ◽  
pp. 707-712 ◽  
Author(s):  
R. FIRSTENBERG-EDEN
Keyword(s):  
Collaborative Study ◽  
Raw Milk ◽  
Plate Count ◽  
Impedance Method ◽  
Standard Plate Count ◽  
Milk Samples ◽  
Automated Method ◽  
Significant Difference ◽  
Standard Plate ◽  
Contamination Levels

The impedance method is a rapid automated method for determining bacteriological contamination levels. A collaborative study was done to establish the reproducibility of the impedance method in predicting counts of raw milk. Frozen and unfrozen raw milk samples, with counts in the range of 9 × 104 to 4 × 107 CFU/ml, were sent to six laboratories to be examined by the standard plate count method (SPC) and by the impedance method which produced Bactometer-predicted counts (BPC). The impedance results showed less variability than SPC among laboratories in all three trials. The variance between split samples was also smaller for the impedance method than for SPC. However, the variance between duplicate plates of the same sample was significantly smaller for SPC than for BPC. In one trial, the means of BPC and SPC were not significantly different, whereas in another trial there was a significant difference of ca. log10 0.27 between the means of the two methods. However, in this trial the extreme differences between laboratories counting the same sample were log10 0.42.

scholarly journals Iodine content in bulk tank milk samples in relation to dairy farm size

2014 ◽  
Vol 83 (10) ◽  
pp. S9-S13 ◽  
Author(s):  
Lenka Vorlová ◽  
Lucia Hodulová ◽  
Ivana Borkovcová ◽  
Hana Přidalová ◽  
Romana Kostrhounová ◽  
...  
Keyword(s):  
Dairy Farm ◽  
Iodine Content ◽  
Dairy Farms ◽  
Raw Milk ◽  
Farm Size ◽  
Milk Samples ◽  
Significant Difference ◽  
Organic Dairy ◽  
Bulk Tank ◽  
Organic Dairy Farms

The aim of this study was to compare the iodine content in raw milk from organic and conventional dairy farms of different sizes. Milk samples were collected between 2012 and 2013, and the iodine content was determined by a Sandell-Kolthoff reaction after dry alkaline digestion of the milk samples. Comparing the iodine content in raw milk samples from small sized dairy farms (116.76 ± 46.29 μg/l) and large sized dairy farms (173.70 ± 35.42 μg/l), a significant difference in iodine content was observed (P ≤ 0.05). The lowest values were found in small and medium dairy farms, 45.30 μg/l and 40.46 μg/l, respectively. High variability (112.92 ± 94.74 μg/l) in the iodine content was detected in raw milk from medium sized dairy farms. When considering milk samples from organic dairy farms (119.29 μg /l ± 40.37) vs. conventional dairy farms (136.55 μg/l ± 42.91), no significant difference was detected. These results indicate higher iodine content in milk from large dairy farms regardless of conventional or organic farming methods.

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