scholarly journals Microbiological, chemical, physical, and proteolytic activities of raw milk after thermal processing

2018 ◽  
Vol 70 (5) ◽  
pp. 1625-1632 ◽  
Author(s):  
H.S. Milaneze ◽  
L.S. Silva ◽  
L.B.M. Kottwitz ◽  
M.A. Zambom ◽  
L.M. Fonseca ◽  
...  
Keyword(s):  
Life Quality ◽  
Raw Milk ◽  
Progressive Increase ◽  
Milk Composition ◽  
Production Chain ◽  
Psychrotrophic Bacteria ◽  
Milk Samples ◽  
Quality Of Milk ◽  
Staphylococcus Spp

ABSTRACT The aim was to evaluate the microbiological, chemical- physical, and shelf-life quality of milk samples after pasteurization (HTST) for 10 days or ultra-high temperature (UHT) treatment for 120 days. Raw milk counts of mesophilic aerobic microorganisms, Staphylococcus spp. and thermotolerant coliforms before HTST and UHT processing were 6.73 and 7.77; 2.84 and 4.30, and 4.68 and 4.37log10, respectively. Pseudomonas spp. were found in raw milk samples. No presence of any other microorganisms studied was detected and no microbial inhibitor was found. Processed samples met microbiological legal requirements. However, aerobic mesophilic counts for HTST pasteurized milk samples stored for 5 and 10 days increased to values comparable to those in raw milk. Composition chemical- physical of all samples were within legal limits. These results demonstrate that, although HTST and UHT processed milk comply with the microbiological standards required by Brazilian law, high microbial counts in raw milk are an issue, possibly due to failures in the early stages of the production chain. Increase in casein macropeptide (CMP), probably because of proteases psychrotrophic bacteria. It is concluded that the quality of raw milk directly influences the progressive increase of the CMP values.

scholarly journals Effect of acidification of raw milk on psychrotrophic microrganims.

2013 ◽  
Vol 2 (2) ◽  
Author(s):  
Marianne Ayumi Shirai ◽  
Maria Lucia Masson
Keyword(s):  
Dairy Products ◽  
Inhibitory Action ◽  
Raw Milk ◽  
Psychrotrophic Bacteria ◽  
Milk Samples ◽  
Ph Reduction ◽  
Quality Of Milk ◽  
Micro Organisms ◽  
Milk And Dairy Products

<p>The contamination of raw milk with psychrotrophic micro-organisms has become a concern because they are able to multiply at refrigeration temperatures and produce heat resistant enzymes that affect the quality of milk and dairy products. The objective of this study was to evaluate the effect of acidification with CO<sub>2</sub> and HCl on mesophilic and psychrotrophic bacteria present in raw milk during cold storage. Raw milk samples were acidified with CO<sub>2</sub> and HCl 1N until pH 6,0 and stored at 5 &deg;C for 10 days. The results showed an average reduction of 1 logarithmic cycle in the growth of psychrotrophic and mesophilic microorganisms in samples treated with CO<sub>2</sub>. Acidification with HCl showed no effect, indicating that inhibitory action was due to CO<sub>2</sub> not by pH reduction.</p><p>&nbsp;</p><p>DOI: http://dx.doi.org/10.14685/rebrapa.v2i2.68</p>

Improved Methods for Quality Assessment of Raw Milk

1988 ◽  
Vol 51 (12) ◽  
pp. 955-957 ◽  
Author(s):  
J. RUSSELL BISHOP ◽  
JIA-YING JUAN
Keyword(s):  
Raw Milk ◽  
Plate Method ◽  
Fresh Sample ◽  
Psychrotrophic Bacteria ◽  
Milk Samples ◽  
Bacterial Enumeration ◽  
Quality Of Milk ◽  
Improved Methods ◽  
Medium Culture

Raw milk samples (203) were obtained from locations throughout Virginia for the purpose of evaluating the presently available techniques, used as is or modified, for enumeration of psychrotrophic bacteria as indicators of the actual quality of milk. Each of the samples was split into two sub-samples, one being tested by various bacterial enumeration methods on the fresh sample, and the other subjected to a preliminary incubation of 13°C or 21°C for 18 h prior to bacterial enumeration. Agar pour plates and Petrifilm dry medium culture plates were both used. Results indicated that the Petrifilm technique was not significantly different from agar pour plate methods as evidenced by correlation values, mean log differences, slopes, and Y-intercepts. The Petrifilm method for the modified (rapid) Psychrotrophic Bacteria Count (mPBC) produced similar overall results (0.96, −0.283, 1.016, −0.340, respectively) to the pour plate method (0.94, 0.272, 0.865, 0.684, respectively) when compared to the standard PBC, and enumeration of colonies on the Petrifilm plates was easier due to the incorporated TTC. A modified Preliminary Incubation Count (mPIC) yielded results not significantly different from those of the PIC (0.94, 0.044, 0.991, 0.169, respectively), and was conducted in less time - 2 d vs. 3 d.

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.

scholarly journals Quality Analysis of Milk in Kathmandu Valley

2018 ◽  
Vol 5 ◽  
pp. 7-10
Author(s):  
Astha Parajuli ◽  
Prasiddhi Rimal ◽  
Rujisha Maharjan ◽  
Richa Chaudhary ◽  
Shashi Bhusan Chaturwedi
Keyword(s):  
Milk Sample ◽  
Milk Fat ◽  
Raw Milk ◽  
Fat Content ◽  
Quality Analysis ◽  
Kathmandu Valley ◽  
Microbiological Analysis ◽  
Milk Samples ◽  
Quality Of Milk

Objectives: This study was carried out to evaluate physiochemical, adulteration and microbial quality of milk sold in Kathmandu Valley. Methods: The study was carried out in Microbiology Laboratory of DAV College. The total of 20 milk samples randomly collected from different places of the valley including 10 pasteurized milk sample and 10 were raw milk sample, were processed for Physiochemical and Microbiological analysis. Result: The laboratory analysis revealed that the pasteurized samples has less mesophilic count as well as coliform count than raw milk samples. About 55% milk samples showed neutralizer test positive and 10% of milk samples were found to be positive for sugar test. However, none of the samples were found to contain starch as an adulterant. The average fat content of milk samples of Kathmandu Valley was 3%. Fat percent was significantly different among different sources of sampling points. The highest milk fat content value was recorded at Pulchowk (3.7%). The average SNF of Kathmandu Valley was 7% in which the pasteurized sample had the highest average SNF (7.3%) and the raw milk had lowest average SNF (6.8%). Conclusion: The significant variation in the physiochemical properties and microbial properties of the milk samples showed that people should be conscious about the consumption of market milk.  

scholarly journals Nutritional and hygienic quality of raw milk intended for consumption in the region of Guelma, Algeria 

2018 ◽  
Author(s):  
A. Bousbia ◽  
S. Boudalia ◽  
Y. Gueroui ◽  
B. Belaize ◽  
S. Meguelati ◽  
...  
Keyword(s):  
Raw Milk ◽  
Physicochemical Characteristics ◽  
Poor Quality ◽  
Fecal Coliforms ◽  
Milk Samples ◽  
Bacteriological Quality ◽  
Quality Of Milk ◽  
Cattle Farms

The main objective of this study is to assess nutritional and hygienic qualities of raw milk collected in situ in dairy cattle farms in the region of Guelma, Algeria. For this purpose, a total of 144 milk samples were collected and analyzed to determine their physicochemical characteristics and bacteriological quality. Results showed an acceptable nutritional quality, with a poor bacteriological quality. The average contamination was 11.69 x 105 CFU ml-1 for total flora, against 23.44 x 105 CFU ml-1 for total Coliforms and 7.34 x 104 CFU ml-1 for fecal Coliforms. In addition, 6% of total samples were positive for Clostridium. For the suspected pathogenic flora, Staphylococcus aureus has been detected in 9 samples; however, all milk samples were devoid of Salmonella. The poor quality of milk reflects the dismal conditions of production and the no-control of hygienic practices.

QUALITY ASSESSMENT OF RAW MILK IN KOSOVO

2018 ◽  
Vol 28 (4) ◽  
pp. 1305-1309
Author(s):  
Emine Uka ◽  
Nexhdet Shala ◽  
Arsim Elshani
Keyword(s):  
Negative Impact ◽  
Raw Milk ◽  
The Other ◽  
Human Consumption ◽  
Monitoring Point ◽  
Milk Processing ◽  
Milk Samples ◽  
Fresh Milk ◽  
Quality Of Milk

Since milk is one of the most consumable products of human consumption and in Kosovo, it is one of the most prosperous agriculture branches and the continued support to farmers from the Ministry of Agriculture, European Commission and USID, through which we will offer knowledge about the quality of this milk. Quality milk production is the ultimate goal and goal of any milk producer and processor. On the other hand, the low quality of milk has a negative impact on all segments of the dairy industry, especially in the fresh milk processing segment.Our work provides testing of raw milk samples taken by farmers who send milk to milk collection points and dairies in order to determine the quality of your milk. As a monitoring point we have received the Vita dairy and Aldi dairy in the period January 2017 - October 2018, and we have presented a comparison of their results.

SOME OBSERVATIONS ON THE BACTERIOLOGICAL KEEPING QUALITY OF MILK PROCESSED BY HIGH TEMPERATURES WITH A 0.6 SECOND HOLDING TIME1 2

1963 ◽  
Vol 26 (10) ◽  
pp. 332-336 ◽  
Author(s):  
D. A. Evans ◽  
Eleanor L. Lachman ◽  
Warren Litsky
Keyword(s):  
Heat Treatment ◽  
Raw Milk ◽  
Plate Heat Exchanger ◽  
Plate Heat ◽  
Milk Samples ◽  
Whole Milk ◽  
Keeping Quality ◽  
Quality Of Milk ◽  
Sterilized Milk

Summary Raw milk was processed through a commercial sized plate heat exchanger at temperatures of 160 F through 260 F with a 0.6 sec hold. Milk samples were collected at increments of 10 F during processing and analyzed for psychrophilic, mesophilic and thermophilic counts initially and at weekly intervals thereafter. All samples were held at 40 F after processing. Results indicated that temperatures of processing at 160 F and 170 F were not sufficient to impart acceptable keeping qualities to whole milk held at 40 F for a period of one week. By comparison, processing temperatures of 180 F through 210 F with 0.6 sec hold appeared to impart to whole milk keeping qualities which were approximately comparable to those observed in milk pasteurized according to present standards. When heat treatment in the range of 220 F through 260 F were used, it was indicated that bacteriological keeping quality of the milk was improved to an extent far beyond that experienced with present day commercial pasteurization. There appeared to be somewhat of a tendency for higher count raw milk related to the level of population in the processed product although the magnitude of this relationship was not clearly defined in all cases. It was evident that this process did not produce “commercially sterilized” milk at the processing temperatures and holding time used.

scholarly journals Evaluation of the Influence of Frequency of Milk Collection and Milking Dayshift on the Microbiological Quality of Raw Milk

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Lucía Reguillo ◽  
Manuela Hernández ◽  
Elisabeth Barrientos ◽  
Fernando Perez-Rodriguez ◽  
Antonio Valero
Keyword(s):  
Heat Treatment ◽  
Energy Savings ◽  
Positive Impact ◽  
Microbiological Quality ◽  
Raw Milk ◽  
Aerobic Bacteria ◽  
Psychrotrophic Bacteria ◽  
Milk Samples ◽  
Agar Method

The aim of this study was to analyze the influence of milk collection frequency (24 h versus 48 h) and milking dayshift (morning and evening) on total mesophilic aerobic bacteria (MAB) and psychrotrophic bacteria (PSY) counts in raw milk samples. MAB counts were determined by flow cytometry (BactoScan) and PSY counts by the plate counting agar method. An univariate statistical analysis was performed to find out significant differences among the studied factors. Results obtained showed that collecting milk every 24 h was effective in reducing MAB and PSY counts by 32 and 18%, respectively, compared to 48 h milk collection. This positive impact allowed reducing up to 4°C the temperature of the heat treatment in the dairy industry, thus involving energy savings of 22%. Milking during the mornings showed a significant reduction of MAB counts in comparison to milking performed during the evenings (P<0.05). These results are highly useful for the improvement of milk quality through the optimization of collection and milking systems set at primary production.

scholarly journals Occurrence of adulterants and preservatives in the Milk Sold in Rural areas of Omdurman, Sudan

2021 ◽  
Vol 2 (3) ◽  
pp. 64-72
Author(s):  
Asged, A. A. Mohammed ◽  
I. E. M. El Zubeir
Keyword(s):  
Hydrogen Peroxide ◽  
Rural Areas ◽  
Chemical Constituents ◽  
Raw Milk ◽  
Cow Milk ◽  
Milk Samples ◽  
Added Water ◽  
Quality Of Milk ◽  
North And South

In the present investigation, the chemical composition of milk was determined and the detection of the presence of some additives and preservatives in raw cow milk obtained from rural area of Omdurman city Sudan was done. The milk samples (n= 120) were obtained from rural areas of North and South Omdurman. Significantly, (P≤0.05) higher values for the chemical constituents of the examined raw milk samples were reported in the samples from South Omdurman compared to those from North Omdurman. In addition, the results showed that the added water was found in 16.7% of the examined milk samples. Also, formaldehyde was used as a preservative in 19.2% of the samples, while boric acid was used as preservative in 25% of the milk samples in South Omdurman. However, sodium bicarbonate, hydrogen peroxide and starch were not detected. It was concluded that milk distributed in North and South Omdurman contains some adulterants. Hence control and monitoring programs should be directed towards the hygienic quality of milk during production and marketing.

Proteinase and phospholipase activities and development at different temperatures of yeasts isolated from bovine milk

2011 ◽  
Vol 78 (4) ◽  
pp. 385-390 ◽  
Author(s):  
Priscilla A Melville ◽  
Nilson R Benites ◽  
Monica Ruz-Peres ◽  
Eugenio Yokoya
Keyword(s):  
Dairy Products ◽  
Room Temperature ◽  
Bovine Milk ◽  
Raw Milk ◽  
Pathogenic Potential ◽  
Proteinase Production ◽  
Different Temperatures ◽  
Quality Of Milk ◽  
Means Of Transmission

The presence of yeasts in milk may cause physical and chemical changes limiting the durability and compromising the quality of the product. Moreover, milk and dairy products contaminated by yeasts may be a potential means of transmission of these microorganisms to man and animals causing several kinds of infections. This study aimed to determine whether different species of yeasts isolated from bovine raw milk had the ability to develop at 37°C and/or under refrigeration temperature. Proteinase and phospholipase activities resulting from these yeasts were also monitored at different temperatures. Five genera of yeasts (Aureobasidium sp., Candida spp., Geotrichum spp., Trichosporon spp. and Rhodotorula spp.) isolated from bovine raw milk samples were evaluated. All strains showed one or a combination of characteristics: growth at 37°C (99·09% of the strains), psychrotrophic behaviour (50·9%), proteinase production (16·81% of the strains at 37°C and 4·09% under refrigeration) and phospholipase production (36·36% of the isolates at 37°C and 10·9% under refrigeration), and all these factors may compromise the quality of the product. Proteinase production was similar for strains incubated at 37°C (16·81% of the isolates) and room temperature (17·27%) but there was less amount of phospholipase-producing strains at room temperature (15·45% of the isolates were positive) when compared with incubation at 37°C (36·36%). Enzymes production at 37°C by yeasts isolated from milk confirmed their pathogenic potential. The refrigeration temperature was found to be most efficient to inhibit enzymes production and consequently ensure better quality of milk. The viability of yeasts and the activity of their enzymes at different temperatures are worrying because this can compromise the quality of dairy products at all stages of production and/or storage, and represent a risk to the consumer.

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