Detection of buffalo milk adulteration with cow milk by capillary electrophoresis analysis.

The addition of cow milk during the production of buffalo mozzarella is a common fraud in dairy industries because of the lower price and greater availability of cow milk throughout the year. The aim of this study was to develop a new, rapid, and robust capillary electrophoresis method for detecting and quantifying cow milk in buffalo milk by exploiting cow α-lactalbumin as a marker of adulteration. In particular, a linear calibration curve was generated, using a training set of calibrators consisting of 7 series of 17 buffalo/bovine whey mixtures, obtained after casein precipitation, with increasing percentages of cow whey. The capillary electrophoresis method showed high linearity (R2 = 0.968), repeatability [relative standard deviation (RSD) = 2.11, 3.02, 4.38, and 1.18%, respectively for 5, 10, 20, and 50% of buffalo/bovine whey mixtures], and intermediate precision (RSD = 2.18, 2.49, 5.09, and 3.19%, respectively, for 5, 10, 20, and 50% buffalo/bovine whey mixtures). Moreover, the minimum amount of detectable fraudulent cow milk was 1%, and the limit of quantification was 3.1%

Evaluation of the capillary electrophoresis method for measurement of immunoglobulin concentration in ewe colostrum

ABSTRACT Capillary electrophoresis (CE) is a technique routinely used in clinical laboratories that allows the separation and quantification of blood serum proteins in a rapid, precise, accurate, and inexpensive manner. Recently, CE has been proposed to separate and measure colostral proteins, but an evaluation of the agreement between CE and radial immunodiffusion (RID) method, currently used to quantify IgG in colostrum, is still lacking. The purpose of this study was to test the ability of a CE instrument, normally used in blood serum protein analysis, to realize the correct quantification of total Ig concentration in ewe colostrum, using RID assay as reference. Colostrum samples (n = 68) were collected from 35 multiparous Sarda ewes at first milking (n = 33) and at 24 h postpartum (n = 35). The mean ± standard deviation of IgG concentration measured by RID and whey colostrum total Ig concentration measured by CE were 54.76 ± 41.82 g/L and 54.70 ± 41.43 g/L, respectively. Lin's concordance correlation coefficient (r = 0.993; 95% confidence interval=0.989 to 0.996) and linear regression analysis results (RID = 1.0022CE − 0.063; R 2 = 0.986) showed an excellent agreement between these 2 methods. Bland-Altman analysis confirmed that CE method can be a suitable alternative to RID: the mean of the differences between CE and RID was −0.055 ± 4.95 g/L (95% confidence interval=−1.25 to 1.14 g/L) and the agreement limits were −9.75 to 9.60 g/L (low limit 95% confidence interval=−11.82 to −7.68 g/L; high limit 95% confidence interval=7.57 to 11.72 g/L). In conclusion, the current study indicates that CE method may be a reliable tool for the quantification of the total Ig concentration in ewe colostrum

Technical note: Capillary electrophoresis as a rapid test for the quantification of immunoglobulin G in serum of newborn lambs

ABSTRACT Finding a rapid and simple method of serum IgG determination in lambs is essential for monitoring failure of passive transfer of immunity. The aim of this study was to assess the ability of capillary electrophoresis (CE), an instrument mainly used in blood serum protein analysis, to estimate IgG content in serum of newborn lambs through determination of only total Ig percentage by comparing the results with those obtained with radial immunodiffusion (RID), the reference method for serum IgG quantification. Serum samples were collected at 24 h after birth from 40 Sarda lambs. The IgG concentration measured by RID and serum total Ig concentration measured by CE were (mean ± standard deviation) 29.8 ± 16.1 g/L and 37.8 ± 15.0%, respectively. Data provided by RID and CE analysis showed a polynomial trend (RID = 0.02CE2 − 0.04CE + 4.13; coefficient of determination, R2 = 0.96), displaying a strong relationship between these 2 methods. Applying the polynomial equation, the IgG values were predicted. Predicted IgG values were highly correlated (r = 0.98) and related (R2 = 0.96) to IgG values obtained by RID assay. These data were subjected to Bland–Altman analysis, revealing a high level of agreement between CE and RID methods with a bias that was not different from 0 (−0.04 g/L) and agreement limits of −6.38 g/L (low) and +6.30 g/L (high). In addition, the linear regression analysis between differences (dependent variable) and average of IgG concentration by CE and RID (independent variable) did not show proportional bias (R2 = 0.01). In conclusion, CE is a reliable instrument for a lamb health monitoring program, where Bland–Altman analysis also confirmed that the CE method can be a suitable alternative to RID

Rapid liquid AP-MALDI MS profiling of lipids and proteins from goat and sheep milk for speciation and colostrum analysis

Rapid profiling of the biomolecular components of milk can be useful for food quality assessment and for food fraud detection. Differences in commercial value and availability of milk from specific species are often the reasons for the illicit and fraudulent sale of milk whose species origin is wrongly declared. In this study, a fast, MS-based speciation method is presented to distinguish sheep from goat milk and sheep colostrum at different phases. Using liquid atmospheric pressure (AP)-matrix-assisted laser desorption/ionisation (MALDI) MS, it was possible to classify samples of goat and sheep milk with 100% accuracy in one minute of data acquisition per sample. Moreover, an accuracy of 98% was achieved in classifying pure sheep milk samples and sheep milk samples containing 10% goat milk. Evaluating colostrum quality and postnatal stages represents another possible application of this technology. Classification of sheep colostrum samples that were collected within 6 hours after parturition and 48 hours later was achieved with an accuracy of 84.4%. Our data show that substantial changes in the lipid profile can account for the accurate classification of colostrum collected at the early and late time points. This method applied to the analysis of protein orthologs of different species can, as in this case, allow unequivocal speciation analysis

Evaluation of freezing point in milk from buffalos reared in Calabria, Italy

Evaluation of freezing point is one of the most common technique used to detect milk adulteration such as addition of external water to increase volume. The aim of this study was to evaluate the freezing point of buffalo milk using infrared spectroscopy and to assess how it is influenced by other milk components. A total of 361 individual buffalo milk samples were collected monthly from March to August of 2017 in a dairy farm in Catanzaro district, Italy. Samples were tested for freezing point, urea, acetone and beta-hydroxybutyrate, percent of fat, protein, lactose, casein, by Fourier Transformed Spectroscopy. The pH and daily milk production were also recorded. Freezing point ranged from -0.574°C to - 0.512°C and the mean values was -0.545°C ±0.010. According to lactation stage, freezing point decreased until 210 days post-partum reaching the minimum value of −0.550°C, then it slightly increased during lactation; according to sampling month the highest and lowest values were recorded in August and June, respectively. A positive correlation between freezing point and lactose content were evidenced (r=0.1806, P<0.05). Moreover, a faintly positive correlation was also found between freezing point and beta-idroxibutirrate (r=0.0869, P<0.05) and acetone (r=0.0096, P<0.05), whereas a negative correlation with fat (r=−0.2356, P<0.05), protein (r=-0.1855, P<0.05), casein (r=-0.2127, P<0.05) and urea (r=-0.1229, P<0.05) was evidenced

Phenotypic antimicrobial resistance profile of isolates causing clinical mastitis in dairy animals

Mastitis is the most frequent and costly disease of lactating animals and is associated with a significant reduction in milk yield, increased cost and culling. Early and specific antibiotic based treatment reduces the severity of the disease. Over the years the extensive use of antimicrobials has led to increase antimicrobial resistance. The present study was designed to investigate the prevalence of microorganisms responsible for mastitis and their antimicrobial resistance pattern. A total of 282 milk samples were collected from different animal species (sheep, cows and goats) with clinical mastitis. Antimicrobial resistance was evaluated for Streptococcus spp. and Staphylococcus spp. In cow samples Streptococcus spp. represented the most frequently isolated genus (33.84%), while Staphylococcus spp. was the most prevalent genus in sheep and goat samples (44.4 and 73.86%, respectively). Gentamicin and chloramphenicol were found to be the most effective drugs against the tested isolates, while the highest resistance rates were observed for amoxicillin, ampicillin, tetracycline, trimethoprim-sulfamethoxazole

Foodborne Pathogen Assessment in Raw Milk Cheeses

General hygienic parameters and selected foodborne pathogens in raw milk cheeses at the retail level were evaluated. A total of 245 raw milk cheese samples were analysed for total bacterial count, Enterobacteriaceae, E. coli, Salmonella spp., Listeria monocytogenes, coagulase-positive Staphylococci, and staphylococcal enterotoxin. Results showed only 3 samples that were not compliant with European rules on staphylococcal enterotoxin, but coagulase-positive Staphylococci were evidenced in all samples tested. Salmonella spp. and Listeria monocytogenes were never detected whereas E. coli was evidenced in 20 samples. Results suggest a need for improvement of good manufacturing practice and milking operation

Suitability of Protein Content Measured by MilkoScan FT-Plus Milk Analyzer to Evaluate Bovine and Ovine Colostrum Quality

The objective of this study was to evaluate MilkoScan FT-plus for the estimation of the immunoglobulin G (IgG) content in bovine and ovine colostrum. Between April and May 2016, a total of 94 colostrum samples (54 from Simmental dairy cows and 39 from Sarda ewes) were collected within 6 h (T0) and after 24 h (T24) from parturition. Colostrum samples were subjected to the radial immunodiffusion (RID) assay for the quantification of IgG and to MilkoScan FT-plus for the estimation of protein content (TP, %), which was then used as an indirect method for the evaluation of colostrum quality. To compare the two methods, correlation and regression analysis of IgG quantification by RID and protein (%) content estimation by MilkoScan FT-plus data was performed using Procedure CORR and Procedure REG of SAS, respectively (version 9.3, SAS Institute Inc., Cary, NC, USA). Thresholds for the classification of good colostrum quality (as determined by RID assay, the gold standard method) were set at 50 g of IgG/L in cows and 20 g of IgG/L in ewes. The concentration of IgG in bovine colostrum assayed by RID showed a variation ranging from 41.45 to 199.97 g/L with an average of 99.85 ± 40.84 g/L at T0, and from 2.83 to 75.93 g/L with an average of 19.76 ± 19.01 g/L at T24. Regarding ovine colostrum, the concentration of IgG assayed by RID ranged from 34.45 to 156.32 g/L with an average value of 77.82 ± 37.58 g/L at T0, and from 5.6 to 69.74 g/L with an average of 27.90 ± 19.81 g/L at T24. Colostrum TP ranged from 3.70 to 23.96% for bovine colostrum and 6.32 to 22.88% for ovine colostrum using MilkoScan FT-plus. MilkoScan FT-plus and RID data were highly and significantly correlated (r = 0.91 for bovine and r = 0.94 for ovine colostrum), and regression analysis showed a strong relationship between IgG concentration provided by RID assay and TP provided by MilkoScan FT-plus (R2 = 0.84 and 0.88 for bovine and ovine, respectively). Optimal cut-off points for the greatest accuracy of TP (%) determined by MilkoScan FT-plus were 12.8% in cows [with 88.9% sensitivity (Se) and 100% specificity (Sp)] and 9% in ewes (with 96.7% Se and 100% Sp). In conclusion, these outcomes indicate that MilkoScan FT-plus as an indirect method may be a reliable tool for the estimation of the total IgG concentration and quality in bovine and ovine colostrum. Moreover, the cut-off levels of 12.8% for bovine and 9% for ovine of TP, seem sufficient to ensure that all poor-quality colostrum can be classified as such, with only a low proportion of good-quality colostrum being misclassified as poor-colostrum, thereby increasing the probability of delivering good-quality colostrum to new-born calves and lambs

Microbial quality evaluation of grated cheese samples collected at retail level in Calabria (Italy)

To evaluate the microbial quality of grated cheese sold in Southern Italy, a total of 47 samples were collected at retail. Enumeration of fungi performed by culture reveled concentration ranging between 1 and 5.56 Log10 CFU/g and between 1 and 4 Log10 CFU/g for yeasts and molds, respectively. Selected mold colonies (n = 95) available from 31 samples (65.96%) were further identified. In total, 27 different mold species were recorded. The top five strains were in descending order as follows: Moniliella suaveolens (21.05%, n = 20), Geotrichum candidum (9.47%, n = 9), Penicillium brevicompactum (7.36%, n = 7), Cladosporium cladosporioides (6.31%, n = 6) and Gliocladium album (5.26%, n = 5). Regarding bacterial growth, Staphylococcal cells were available from 19 out of 47 (40.42%) collected samples with a range from 1.30 to 5.15 Log10 CFU/g. Staphylococcus aureus-like colonies were not detected and similarly, pathogenic Listeria monocytogenes Salmonella and Escherichia coli was not isolated while two colonies were identified as Listeria innocua. To prevent any potential contamination and growth of pathogenic and spoilage microorganisms in dairy products including grated cheeses high hygiene standards need to be considered