Analytical methods used to quantify isoflavones in cow's milk: a review

peer reviewedThis paper provides an update and comprehensive review of the analytical methods used for quantifying isoflavones and their metabolites in cow’s milk. Isoflavones are secondary plant metabolites that are similar to 17 β-estradiol in chemical structure. They form one of the most common categories of phytoestrogens. Numerous health benefits have been attributed to isoflavones, but many of these compounds are also considered to be endocrine disruptors, with adverse effects on health. These contradictory trends offer an attractive prospect for future research, and therefore, sensitive and reliable analytical methods are required to clarify various issues about isoflavones. For this review, a structured methodology was used to select 26 relevant articles published between 2005 and 2015 from the Scopus and CAB Abstract databases. The review discusses individual steps of the analytical procedures described in these articles, including sample preparation, instrumental analysis and validation. The most commonly used analytical procedure is sample preparation involving liquid-liquid extraction and an enzymatic hydrolysis step followed by liquid chromatography with mass spectrometry analysis. Currently, however, there is no standardized procedure for the sample preparation and analysis of isoflavones in milk.PhytoHealt

Potential Estimation of Minerals Content in Cow Milk Using Mid-Infrared Spectrometry

Mineral contents in milk influence the humanand animal health. The variation of sodium (Na) could also be a good indicator of mastitis and are related to the milk fever. A low intake of calcium (Ca) promotes the osteoporosis in human. Consequently, knowingregularly the mineral contents in milk could be interesting. Unfortunately, the commonchemical analyses used to measure theconcentrations of mineral inmilk areexpensive.Theaimof this study was todevelopsome calibration equations to predict the contents of mineral directly in bovine milk using mid-infrared (MIR) spectrometry. Using a principal components approach, 70 samples were chosen based on their spectral variability from the 1609 collected milk samples. A total of 14 samples were considered as outliers. So, 57 samples were analyzed by inductively coupled plasma atomic emission spectrometry (ICP-AES) to estimate the reference concentrations of minerals. Based onthese values and the corresponding spectra, 3 calibration equations were built permitting to predict the contents of Ca, Na and phosphorus (P). To assess the accuracy of the developed equations, a full cross-validation was applied. In the same way, the RPD ratio corresponding to the ratio of the standard deviation to the standard error of cross-validation was estimated. The best accuracy was observed for the calibration equations estimating the contents of Ca (R2cv 0.82, RPD 2.35) and P (R2cv 0.77, RPD 2.06). In conclusion, the MIR spectrometry seemed to be a good alternative method to predict the contents of Ca and Pin bovine milk

Determination of equol content in milks marketed in Wallonia (Belgium)

PhytoHealt

Application de la méthodologie des surfaces de réponse pour optimiser les préparations d'échantillons en laboratoire

PhytoHealt

Impact of skimming and microfiltration processes on equol concentration in milk

Equol is a microbial metabolite of isoflavones that could be used as therapeutic agent against several diseases and cancers. Cow's milk could be a potential source of equol in the human diet, but more studies are needed on the changes in equol concentration during the technological processing of milk and dairy products. This first exploratory study sought to assess the impact of industrial skimming and microfiltration processes on equol concentration in conventional cow's milk. The milk samples used in this study came from bulk cow’s milk collected in Wallonia (Belgium), by a local dairy and processed in a local cheese factory. Six random sampling were conducted during spring and, for each of them, samples from raw, skimmed and microfiltered milk were analyzed. Equol was present in all samples at a concentration of between 3.2 and 10.3 µg.L-1. A Wilcoxon's signed rank test was then performed on the difference of data, having raw milk as reference, irrespective of the collection date. The results showed that the skimming process slightly increased the equol concentration in milk and therefore that equol had no or little affinity with the lipid milk fraction. The results also showed that, with the microfiltration process, a small proportion of equol was retained. Equol concentration has returned to the same level as that found in raw milk. This might be because of a chemical affinity either with bigger molecules that are physically retained or through direct interaction with the membrane. This scoping study paves the way for more extensive studies on the interaction between equol and other components of the milk.PhytoHealt

Validating the use of an ultra-performance liquid chromatography with tandem mass spectrometry method to quantify equol in cow's milk

Cow’s milk can be used as a potential source of equol in the human diet. In order to study human intake, however, it is necessary to develop a reliable and sensitive analytical method. This paper reports on the validation of an analytical method using ultra-performance liquid chromatography coupled with a tandem mass spectrometry detector to quantify the equol in commercial milks (raw, whole, semi-skimmed, and skimmed milk). The equol was initially released using enzymatic hydrolysis, and it was then extracted using a double liquid/liquid extraction. The analytical method produced a linear calibration curve with a high correlation coefficient (R 2 ≥ 0.996) between 5 and 1,000 ng.mL−1. Good intra- and inter-day precision (≤5.3% and ≤ 5.2%, respectively) and accuracy (≤8.6%) were achieved. The recovery rate differed slightly among the different types of milk, ranging between 60.6 ± 1.09% and 82.3 ± 5.21%. Good method repeatability was observed (<15%). There was neither matrix effect nor carry-over effect, and the sample extracts were stable for at least 7 days of storage at −21 °C and 5 °C. The method proved to be specific, sensitive, precise, and accurate and was used for the first time to quantify the equol content in Belgian commercial cow’s milk. In all the samples analyzed, equol was present at a concentration ≥10 ng.mL−1 and had a significantly higher content in organic than in conventional milk. The study also found that the mean concentrations of equol were similar for each type of commercial conventional cow’s milk.PhytoHealt

Incidence de facteurs alimentaires sur l'obtention de résultats faux positifs lors de la détection des antibiotiques dans le lait par la méthode Delvotest SP®

The study described in this paper was performed to show the influence of feed complemented by minerals, oligo-elements and vitamins (CMV) on the results of Delvotest SP®. Three trials were developed. In the first trial, a group of 13 dairy cows was divided into two subgroups of six and seven cows, receiving the first one a feed basis without CMV, the second one, the same feed basis added of 100 g CMV per day. During the second trial, the dose of CMV was doubled for the last seven cows. During the third trial, all the 8 cows were grazing. The four cows of the test group received 200 g of CMV per day. The two homogeneous groups of cows (somatic cells, number of lactations) were followed for detection of inhibitors in milk using Delvotest SP®. The test gave positive results with milk from complemented cows during the first and the second trials. All results were negative during the third trial. Feed appears to be a factor that may give false positive results in the determination of antibiotics in milk with Delvotest SP®