A Vapor Pressure Osmometer for Determination of Added Water in Milk

1975 ◽  
Vol 38 (4) ◽  
pp. 204-207 ◽  
Author(s):  
K. PENSIRIPUN ◽  
E. C. CAMPBELL ◽  
G. H. RICHARDSON
Keyword(s):  
Vapor Pressure ◽  
Collaborative Study ◽  
Raw Milk ◽  
Cow Milk ◽  
Filter Paper Disc ◽  
Milk Samples ◽  
Added Water ◽  
Sample Chamber ◽  
Paper Disc

A vapor pressure osmometer requiring a 5- to 7-microliter sample to saturate a 0.64 cm filter paper disc fixed a digital readout of milliosmolality in 110 sec. A coefficient of variability of 0.70 was obtained on a raw milk sample tested 25 times when an acetone impregnated tissue was used to clean the sample chamber between tests. Two hundred individual cow milk samples from 20 herds averaged 280.0 ± 3.0 milliosmols. Milk samples containing up to 25% added water were evaluated on both the vapor pressure osmometer and a thermistor cryoscope with a resultant correlation coefficient of 0.991. A collaborative study involving eight hospital and industry laboratories was conducted. When the results of two laboratories were discarded, due to instrument maintenance problems, there were no significant differences among the laboratories in their abilities to quantitate added water in milk.

scholarly journals HPLC-DAD multi-residue method for determination of florfenicol, penicillin and tetracycline residues in raw cow milk

2021 ◽  
Vol 2 (3) ◽  
pp. 01-08
Author(s):  
Ali Jaber ◽  
Zeinab Zahreddine ◽  
Simon Abou Haidar ◽  
Chadi Hosri ◽  
Ghassan Ibrahim ◽  
...  
Keyword(s):  
High Performance ◽  
Solid Phase ◽  
Raw Milk ◽  
Reversed Phase ◽  
Cow Milk ◽  
Antibiotic Residues ◽  
Milk Samples ◽  
Antibiotics Residues ◽  
Tetracycline Residues

The existence of antibiotic residues in edible products constitutes a health problem to the consumers. Reversed-phase high-performance liquid chromatography with diode array detection (HPLC–DAD) was optimized and validated for the simultaneous determination of florfenicol (FF), penicillin (PE), and tetracycline (TC) residues in dairy raw milk samples. The determination of these antibiotics was carried out on HP-ODS Hypersil C18 (5μm, 125*4 mm) column at a flow rate (1mL/min) and temperature (35 ⁰C). The extraction method includes deproteinization of the milk sample followed by a solid-phase extraction (SPE) clean-up. The method was validated according to the European Commission Decision 2002/657/EC and the International Conference of Harmonization Guidelines. The recoveries for the studied antibiotics ranged from 82–111.54 % making the method suitable for performing routine analysis. The proposed method was applied for the analysis of antibiotic residues in 50 dairy raw milk samples collected from many regions in Lebanon. The results showed the occurrence of these antibiotics residues in milk collected from different Lebanese regions. The numbers indicate that 22 % of milk samples were found to be positive for FF, 42 % for PE, and 28 % for TC residues.

scholarly journals Simultaneous Determination of Multiple Tetracycline Residues in Milk by Metal Chelate Affinity Chromatography: Collaborative Study

1996 ◽  
Vol 79 (1) ◽  
pp. 29-42 ◽  
Author(s):  
Mary C Carson ◽  
Wayne Breslyn ◽  
J Carmany ◽  
S Cross ◽  
W H Farrington ◽  
...  
Keyword(s):  
Metal Chelate ◽  
Collaborative Study ◽  
Raw Milk ◽  
Milk Samples ◽  
Relative Standard ◽  
Control Milk ◽  
Fast Flow ◽  
Tetracycline Residues ◽  
Liquid Chromatographic

Abstract To meet federal and state regulatory needs, a liquid chromatographic (LC) method with ultraviolet (UV) detection was developed for determination of 7 tetracyclines at 30 ng/mL in milk. Raw milk samples are defatted, acidified, and centrifuged to remove proteins, and tetracyclines are specifically absorbed from the milk by chelation with metal ions bound to small Chelating Sepharose Fast Flow columns. Tetracyclines are removed from these columns with EDTA-containing buffer, and extracts are further cleaned by ultrafiltration. Finally, extracts are concentrated and analyzed simultane ously by using on-line concentration. This method was validated in a collaborative study that involved 11 laboratories, including the authors’ laboratory. Each laboratory was asked to prepare and analyze known control and fortified milk samples, as well as 18 coded blind samples. Eight laboratories completed all analyses. Average interlaboratory recoveries for the known fortified samples ranged from 59% (methacycline at 15 ng/mL) to 78% (oxytetracy cline at 60 ng/mL). Average recovery for each of 7 residues at 30 ng/mL were between 60 and 110%, meeting single-residue guidelines for accuracy set by the U.S. Food and Drug Administration. Reproducibility relative standard deviation (RSDR) for the known fortified samples varied from 11 to 39%, with 6 of 7 residues at the 30 ng/mL level having RSDR values at or below 20%. Seven of 8 laboratories correctly identified blind control milk samples and all 28 residues present in blind samples. The metal chelate affinity—LC method for determination of multiple tetracycline residues in milk has been adopted first action by AOAC INTERNATIONAL.

scholarly journals Chemical Composition and Screening of Aflatoxin M1 in Cows’ Milk in Gadarif Town, Sudan

2021 ◽  
Author(s):  
Kamal M. A. Abdalmahmoud ◽  
El Tahir S. Shuiep ◽  
Ibtisam E El Zubeir ◽  
Omer H. M. Arabi
Keyword(s):  
Chemical Composition ◽  
Freezing Point ◽  
Screening Method ◽  
Raw Milk ◽  
Aflatoxin Contamination ◽  
Cow Milk ◽  
Aflatoxin M1 ◽  
Milk Samples ◽  
Important Health ◽  
Added Water

Abstract Background: Milk is a perfect complete perishable food that could be adulterated or contaminated by wide varieties of substance throughout the chain of its production. Of these aflatoxins M1 was considered as an important health risk associated with the milk. The objectives of this study are to analyse milk samples, for chemical composition and detection of aflatoxin M1. Method: One hundred milk samples were collected from different sources randomly; 35 samples from farms, 35 samples from sale points and 30 samples from groceries in Gedarif town. Milk-Kana was used for determination of chemical composition (fat, solids not fat, lactose and protein and analysis of freezing point, density and added water) and Unisensor kits were used as screening method for detection of aflatoxin M1 in milk. Results: The chemical composition of milk samples collected from farms, sales points and groceries showed lower content of the fat (3.4±1.3%, 3.4±1.3% and 3.5±1.25%), solids not fat (7.7±1.1%, 8.1±1.7% and 8±1%), lactose (4.2±0.6%, 4.4±0.8% and 4.3±0.5%) and protein (3±0.4%, 3±0.5% and 3±0.4%). The freezing point of milk samples revealed -.503±.079, -.524±.007 and -.522±.099 °C, while the density showed 0.025±0.003, 0.026±0.005 and 0.026±0.003 gm/cm3, respectively. Moreover the added water was found as 10.6±11.6%, 10.6±10.4% and 8.7±8.2% in the samples collected from farms, sale points and groceries, respectively. The occurrence of aflatoxin M1 in raw milk samples were found in 22(27.50%) of the samples. The presence of aflatoxin contamination was high in milk samples collected from sales points (15.0%) followed by farms (11.25%) compared to those obtained from groceries (1.25%). Conclusion: The lower chemical composition of milk ns the high added water suggested adulteration of milk. Moreover the presences of aflatoxin M1 in the milk samples might indicate that the cow milk was contaminated with aflatoxins through feed. Hence this study recommended that good hygienic practices should be considered in Gadarif town. Similarly regulations and lows for selling the milk should be implemented by the official authorities.

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.

Cryoscopy of Milk: Effect of Variations in the Method

1966 ◽  
Vol 49 (3) ◽  
pp. 511-515 ◽  
Author(s):  
R W Henningson
Keyword(s):  
Statistical Analysis ◽  
Sample Size ◽  
Freezing Point ◽  
Collaborative Study ◽  
Sample Temperature ◽  
Milk Samples ◽  
Two Samples ◽  
Temperature Rate

Abstract Bath level, sample temperature, rate of stirring, degree of supercooling, sample size, sample isolation, and refreezing of the sample were the variables in the thermistor cryoscopic method for the determination of the freezing point value of milk chosen for study. Freezing point values were determined for two samples of milk and two secondary salt standards utilizing eight combinations of the seven variables in two test patterns. The freezing point value of the salt standards ranged from –0.413 to –0.433°C and from –0.431 to –0.642°C. The freezing point values of the milk samples ranged from –0.502 to –0.544°C and from –0.518 to –0.550°C. Statistical analysis of the data showed that sample isolation was a poor procedure and that other variables produced changes in the freezing point value ranging from 0.001 to 0.011°C. It is recommended that specific directions be instituted for the thermistor cryoscopic method, 15.040–15.041, and that the method be subjected to a collaborative study.

scholarly journals Indirect and Direct Determination of the Casein Content of Milk by Kjeldahl Nitrogen Analysis: Collaborative Study

1998 ◽  
Vol 81 (4) ◽  
pp. 763-774 ◽  
Author(s):  
Joanna M Lynch ◽  
David M Barbano ◽  
J Richard Fleming
Keyword(s):  
Standard Deviation ◽  
Nitrogen Content ◽  
Relative Standard Deviation ◽  
Collaborative Study ◽  
Direct Determination ◽  
Raw Milk ◽  
Method Performance ◽  
Relative Standard ◽  
Milk Casein

Abstract The classic method for determination of milk casein is based on precipitation of casein at pH 4.6. Precipitated milk casein is removed by filtration and the nitrogen content of either the precipitate (direct casein method) or filtrate (noncasein nitrogen; NCN) is determined by Kjeldahl analysis. For the indirect casein method, milk total nitrogen (TN; Method 991.20) is also determined and casein is calculated as TN minus NCN. Ten laboratories tested 9 pairs of blind duplicate raw milk materials with a casein range of 2.42- 3.05℅ by both the direct and indirect casein methods. Statistical performance expressed in protein equivalents (nitrogen ⨯ 6.38) with invalid and outlier data removed was as follows: NCN method (wt%), mean = 0.762, sr = 0.010, SR = 0.016, repeatability relative standard deviation (RSDr) = 1.287℅, reproducibility relative standard deviation (RSDR) = 2.146%; indirect casein method (wt℅), mean = 2.585, repeatability = 0.015, reproducibility = 0.022, RSDr = 0.560℅, RSDR = 0.841; direct casein method (wt℅), mean = 2.575, sr = 0.015, sR = 0.025, RSDr = 0.597℅, RSDR = 0.988℅. Method performance was acceptable and comparable to similar Kjeldahl methods for determining nitrogen content of milk (Methods 991.20, 991.21,991.22, 991.23). The direct casein, indirect casein, and noncasein nitrogen methods have been adopted by AOAC INTERNATIONAL.

scholarly journals Simultaneous Determination of C18 Fatty Acids in Milk by GC-MS

Separations ◽  
2021 ◽  
Vol 8 (8) ◽  
pp. 118
Author(s):  
Meiqing Chen ◽  
Yangdong Zhang ◽  
Fengen Wang ◽  
Nan Zheng ◽  
Jiaqi Wang
Keyword(s):  
Fatty Acids ◽  
High Sensitivity ◽  
Raw Milk ◽  
Uht Milk ◽  
Milk Samples ◽  
Accuracy And Precision ◽  
Different Temperatures ◽  
Chromatographic Resolution ◽  
Commercial Milk

The determination of C18 fatty acids (FAs) is a key and difficult aspect in FA profiling, and a qualified method with good chromatographic separation and high sensitivity, as well as easy methylation, is required. A GC-MS method was established to simultaneously determine C18 FAs in milk. To simplify the methylation protocol for milk samples, besides a base-catalyzation methylation (50 °C for 20 min), the necessity of an additional acid-catalyzation was also studied using different temperatures (60 °C, 70 °C, 80 °C, and 90 °C) and durations (90 min and 150 min). The results showed that the chromatographic resolution was improved, although three co-eluted peaks existed. The base-catalyzation was sufficient, and an additional acid-catalyzation was not necessary. The proposed method was validated with good sensitivity, linearity, accuracy, and precision, and then applied in determining C18 FAs in 20 raw milk and 30 commercial milk samples. UHT milk presented a different profile of C18 FAs from raw milk and PAS milk samples, which indicated that excessive heating could change the profile. Overall, the proposed method is a high-throughput and competent approach for the determination of C18 FAs in milk, and which presents an improvement in chromatographic resolution and sensitivity, as well as a simplification of methylation.

Determination of Viable Bacterial Populations in Raw Milk within 20 Minutes by Using a Direct Epifluorescent Filter Technique

1997 ◽  
Vol 60 (7) ◽  
pp. 874-876 ◽  
Author(s):  
CLAUDE P. CHAMPAGNE ◽  
NANCY J. GARDNER ◽  
JULIE FONTAINE ◽  
JACQUES RICHARD
Keyword(s):  
Raw Milk ◽  
Plate Count ◽  
Bacterial Populations ◽  
Filter Technique ◽  
Milk Samples ◽  
Standard Plate ◽  
Plate Counts ◽  
Direct Epifluorescent Filter Technique ◽  
Triton X

The results from a shortened procedure for the direct epifluorescent filter technique (DEFT) determination of viable bacterial populations in raw milk were compared to standard plate counts. Shortening the prefiltration trypsin-Triton X-100 incubation period from 10 to 3 min enabled the completion of the analysis within 20 min. The short DEFT method results had a correlation coefficient (r) of 0.81 with plate counts. With respect to precision, the average difference between values of duplicate plate count analyses was 0.16 log units; that of the short DEFT was 0.14 log units. The slopes of the regressions equations were less than 1, indicating that a direct correlation is not achieved. Short DEFT values were 0.17 log units higher than those of plate counts on milk samples containing less than 10,000 CFU/ml. For milk samples containing counts over 10,000 CFU/ml, short DEFT values averaged only 0.05 log units above plate count readings. Daily preparation of the stain appears unnecessary since acridine orange solutions stored for up to 2 days at 4°C did not produce results significantly (P > 0.05) different from those obtained with fresh solutions. The short DEFT method has potential for the assessment of the bacteriological quality of raw milk in tanker deliveries.

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