An ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the simultaneous quantitative determination of fumonisin B1 (FB1), fumonisin B2 (FB2) and fumonisin B3 (FB3) residues in milk powder and milk has been established. The samples were extracted with methanol-acetic acid (98:2, V/V), diluted, cleaned up by immunoaffinity chromatography (IAC), and blown to dryness under nitrogen. The residue was re-dissolved and detected using an electrospray ionization source (EIS) in the positive ion mode with multiple reaction monitoring (MRM) and quantitative analysis was performed by the isotope-labeled internal standard method. The limit of quantification was 10 μg/kg for FB1, FB2 and FB3 in milk powder and milk. The recoveries at spiked concentration levels of 10–400 μg/kg were 92.8%–107.5%, with relative standard deviations (RSD) of 2.0%–4.3%. The matrix effects were 96.25%–122.84%. This method was characterized by short analysis time and was suitable for the determination of fumonisin residues in different dairy products.

In this study, the bioinformatics software DNAStar and Geneious and multiple reaction monitoring mass spectrometry (MRM-MS) were used to predict the linear epitope parameters, secondary structure content and epitope regions of bovine whey proteins. Meanwhile, relative quantification of linear allergenic epitopes was carried out. The results indicated that α-lactalbumin (α-LA) and β-lactoglobulin (β-LG) had 7 and 10 linear epitope regions, respectively. The secondary structure of α-LA and β-LG mainly consisted of α-helix, followed by β-turn, β-sheet and random curling, indicating that the structure of α-LA and β-LG made them more likely to become epitopes. Alkaline, protamex and flavourzyme treatment effectively reduced the linear allergenic epitopes of α-LA and β-LG by 50.0%–80.0%, with this effect being more pronounced for β-LG. The relative quantitation results showed that the content of 95.0% of linear epitope peptides was significantly reduced.

The objective of this study was to establish a method for detecting the residue of dicamba in cow milk by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The sample was extracted with 0.5% formic acid in acetonitrile, and the extract was purified by sodium chloride salting out, and separated on an Acquity UPLC BEH C18 column (100 mm × 2.1 mm, 1.7 μm) by gradient elution using a mobile phase composed of acetonitrile and 0.01% formic acid aqueous solution. Identification and quantification were achieved using an electrospray ionization source in the negative ion mode with multiple reaction monitoring (MRM). Under optimized pretreatment and instrumental conditions, good linearity was observed in the concentration range of 5.0–250.0 μg/L with correlation coefficient (r) more than 0.999. The limit of detection (LOD) and limit of quantification (LOQ) of the proposed method were 5 and 10 μg/kg, respectively. The recoveries of dicamba at spiked concentration levels of 10, 20 and 200 μg/kg were 104.3%, 101.5% and 96.2% with relative standard deviations (n = 6) of 3.0%, 2.0% and 1.5%, respectively. This method is simple, accurate, repeatable, and suitable for the rapid detection of dicamba in milk.

A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was established for the determination of nonylphenol in milk powder. Samples were extracted with acetonitrile and cleaned up with a solid phase extraction column. The analytes were separated on a Waters ACQUITY UPLC BEH C18 column (2.1 mm × 50 mm, 1.7 μm), detected by electrospray ionization in the multiple reaction monitoring (MRM) mode, and quantified by an external standard method. The results showed that good linearity was observed in the concentration range of 1–200 ng/mL (R2 > 0.99). The limit of detection（LOD, RS/N = 3）was 2 μg/kg and the limit of quantitation (LOQ, RS/N = 10）was 5 μg/kg. The recoveries at different spiked levels were between 81.10% and 107.39% with relative standard deviation (RSD) ranging from 1.97% to 9.73%. This method has the advantages of accurate results, small background interference, simple operation, good stability and short pretreatment time, and is useful for the detection of nonylphenol in milk powder.

Functional proteins in milk, including α-lactalbumin, β-lactoglobulin, lactoferrin, lactoperoxidase, β-casein and milk fat globule membrane protein, have been reported to have important physiological functions and play important roles in human health and thus, they have attracted widespread attention from researchers and manufacturers. However, there is a bottleneck for the development of techniques for the separation of functional proteins from milk, which restricts their industrial production and practical application. In this paper, the mature techniques for the separation and purification of six functional proteins from milk are summarized, with special reference to their application conditions and experimental scale, in order to provide a basis the separation and purification of functional proteins from milk in laboratories and factories and the development of new functional milk protein products.

Human milk oligosaccharides have received widespread attention due to their unique probiotic effects. The composition and structure of oligosaccharides from the milks of different mammals are different. Some probiotics represented by bifidobacteria evolve a relatively complete metabolic mode of milk oligosaccharides. Compared with other prebiotics, milk oligosaccharides show more health benefits such as inducing the colonization of bifidobacteria and increasing the diversity of intestinal flora.

Constructing an efficient and safe producer strain is a prerequisite for biosynthetic production of 2’-fucosyllactose. The number and technical content of recent patents on 2’-fucosyllactose biosynthesis applied for in China are reviewed in this paper, indicating that over 80 percent of the patents focused on the construction of recombinant strains by optimizing the metabolic pathways, overexpressing 2’-fucosyllactose biosynthesis-related enzyme genes, and developing more safe and efficient host strains. However, after a review of China’s patented technologies in this regard, we found that research on the biosynthetic production of 2’-fucosyllactose in a pilot scale or above is weak, and there is a lacuna in utility and industrially oriented patented technologies, which will bottleneck the 2’-fucosyllactose biosynthesis industry in China.

An ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the simultaneous quantitative determination of 21 β-agonists in milk. The samples were hydrolyzed and cleaned up a solid-phase extraction column. The analytes were separated by UPLC with an Acquity UPLC BEH C18 column (50 mm × 2.1 mm, 1.7 μm) using a gradient mobile phase consisting of 0.1% formic acid aqueous solution and methanol (10 : 90, V/V). Identification and quantification were achieved by UPLC-MS/MS with multiple reaction monitoring (MRM) under the positive ion mode The limit of quantitation of all β-agonists was 0.05 μg/kg. The average recovery varied from 61.0% to 124.3% at spiked concentration levels of 0.05, 0.10 and 0.50 μg/kg with relative standard deviations (RSDs) of 2.39%–10.66%. Our results demonstrate that the method is stable, accurate and sensitive, and can be used for the determination of the 21 β-agonists residues in milk.

Inductively coupled plasma emission spectrometry (ICP-OES) was used to determine the contents of 12 trace elements (K, Na, Ca, Mg, Fe, Zn, Cu, Mn, P, Sr, Al, and Cr) in premixed feed and crude feed for dairy cows. Samples were pretreated with microwave digestion before being analyzed. The calibration curves of all elements were linear with correlation coefficients above 0.999 8. The spiked recoveries for this method were 90.0%–106.9%, and the coefficients of variance (CV) for six replicate determinations were 0.69%–8.70%. With the advantages of low limits of detection and high sensitivity and accuracy, this method could be useful for the simultaneous determination of multiple trace elements in dairy feeds.

An ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the quantitative determination of salicylic acid in milk and dairy products was developed. The sample was extracted with 1% acidified acetonitrile, and then the extract was purified by solid-phase extraction (SPE) with an HLB cartridge. The separation was performed on an Acquity UPLC BEH C18 chromatographic column (50 mm × 2.1 mm, 1.7 μm）with gradient elution using 0.1% aqueous formic acid-acetonitrile as the mobile phase. The target compound was monitored under the negative ion mode with an electrospray ionization (ESI) source and quantified by external standard method. The results demonstrated that the linear range of the proposed method was from 0.5 to 50.0 ng/mL with a correlation coefficient (R2) > 0.999. The average recovery of salicylic acid in different matrixes spiked at low, medium and high levels varied from 68.3% to 111.7%, and the relative standard deviations (RSDs) of precision were between 3.3% and 15.2%. The limits of detection (LODs) were 5.0 and 10.0 μg/kg in milk and milk powder, respectively. This method can meet the requirements for the determination of different salicylic acid levels in milk and dairy products.

In this paper, an ion chromatography method for the determination of galactooligosaccharides (GOS) in milk powder was established. The protein in the sample was precipitated by acetonitrile, and GOS was extracted with acetonitrilewater and purified using a C18 column (or RP column) to remove impurities. The analyte was separated using an ion chromatograph equipped with quaternary gradient pumps and detected with a pulse amperometric detector. The calibration curve of this method had good linearity in the range of 10–300 μg/mL, and the results from repeated sample measurements were stable. The recovery rates from blank samples spiked at levels of 500–2 000 mg/100 g were 82.1%–98.0%. To sum up, this method required simple sample pretreatment and gave accurate results, and it could be suitable for the determination of the GOS content in milk powder samples.

An ultra performance liquid chromatography-tandem mass spectrometry method for the simultaneous quantitative determination of four tetracycline residues in dairy products, including milk, yogurt and milk powder, has been established. In this method, the pretreatment and instrument operating conditions were optimized. Tetracycline residues were extracted into EDTA-Mcllvaine buffer and then cleaned up by an HLB solid-phase extraction cartridge. After the residues were eluted with a mixture of methanol and acetonitrile (1:9, V/V), the eluate was blown to dryness under nitrogen. The resulting residue was then redissolved. The analysis was carried out using positive ion electrospray ionization under the multiple reaction monitoring mode. The limits of quantification were 10 μg/kg for tetracycline, oxytetracycline, chlortetracycline and doxycycline in milk powder; the limits of quantification were 2 μg/kg in milk and yogurt. The recoveries of the tetracyclines fortified at levels from 2 to 100 μg/kg ranged from 63.1% to 100.6% with relative standard deviation of 1.8%–10.7%, and the matrix effects were 100.5%–122.1%. In conclusion, this method is accurate, rapid and highly sensitive and exhibits good repeatability and wide linearity. Thus it is suitable for the determination of tetracycline antibiotic residues in milk, yogurt and milk powder.

An ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the simultaneous quantitative determination of fipronil and its metabolites in whole egg powder, egg yolk powder and dairy products was developed. Samples were extracted with acetonitrile and saturated sodium chloride solution was added to separate the organic and aqueous phases. The supernatant after low-temperature precipitation of protein was applied onto an HLB solid-phase extraction cartridge for purification. The chromatographic separation was accomplished with an Acquity UPLC BEH C18 column (2.1 mm × 50 mm, 1.7 μm) using gradient elution with a mobile phase consisting of a mixture of acetonitrile and water. The analytes were detected using a negative electrospray ion source under the multiple reaction monitoring mode and quantitated by the external standard method. The results demonstrated that the linear ranges were from 0.5 to 20.0 μg/L with good correlation coefficients (R2 > 0.990). The limit of detection and the limit of quantitation were 0.2 and 1.0 μg/kg for all analytes, respectively. The recoveries of fipronil and its metabolites in different matrixes at spiked concentration levels of 1, 2, 4 and 20 μg/kg varied from 63.4% to 118.7%, with relative standard deviations between 0.7% and 10.3%. The method proved to besensitive, accurate and suitable for the rapid quantification of fipronil, fipronil sulfide, fipronil sulfone and fipronil desulfinyl in protein-rich foods.

An ultra performance liquid chromatography-tandem mass spectrometry method for the simultaneous quantitative determination of four cephalosporin residues in dairy products, including milk, yogurt and milk powder, has been established. The samples were extracted with 5% formic acid acetonitrile. After being purified by solid-phase microextraction using an Oasis PRIME HLB cartridge, the extract was blown to dryness under a stream of nitrogen gas and then re-dissolved. The analysis was carried out using a positive electrospray ion source in the multiple reaction monitoring mode. The limit of quantification was 32 μg/kg for cefalexin, cefapirin, cefalonium and cefquinome?in milk powder; the limit of quantification was 4 μg/kg in milk and yogurt. The recoveries at spiked concentration levels of 4-150 μg/kg were 63.3%-112.1%, with relative standard deviations of 1.6%-10.5%. The matrix effects were 108.77%-379.91%. This method was characterized by short analysis time and was suitable for the determination of cephalosporin residues in different dairy products.

An ultra performance liquid chromatography-tandem mass spectrometry method for simultaneous quantitative determination of four quaternary ammonium compounds in dairy products, including milk, yogurt and milk powder, has been established. Quaternary ammonium compounds from samples were extracted with methanol and cleaned up by solid phase extraction using a weak cationic exchange reversed-phase adsorbent (WCX). The chromatographic separation was achieved using a mixture of formic acid and methanol (2:98, V/V) as the elution solvent. The eluate was evaporated to dryness under a stream of nitrogen gas and the residue was re-dissolved prior to analysis using a positive electrospray ion source in the multiple reaction monitoring mode. The limit of quantification was 10 μg/kg for dodecyl trimethyl ammonium bromide, benzylcetyldimethyl ammonium chloride, tetradecyl dimethyl benzyl ammonium chloride and didecyl dimethyl ammonium chloride in all three dairy products. The recoveries at spiked concentration levels of 10-200 μg/kg were 81.4%-105.6%, with relative standard deviations ranging from 0.97% to 6.04%. The matrix effect was in the range of 90.89%-234.94%. This method was rapid, accurate, repeatable and was suitable for the determination of quaternary ammonium compounds in various dairy products.

A method for the determination of nonylphenol in liquid milk by using ultra high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed. Samples were extracted using acetonitrile as extraction solvent and the organic phase was separated from the aqueous phase by adding saturated sodium chloride solution. The analyte was cleaned up using a ProElut PAEs Glass solid-phase extraction catridge and then separated on a Waters ACQUITY UPLC BEH C18 column (2.1 mm × 50 mm, 1.7 μm) using gradient elution with 0.1% ammonia water-methanol as mobile phase. The detection was performed by negative electrospray ionization under the multiple reaction monitoring mode and the quantitation was carried out by an internal standard method. The results showed a good linear relationship (R2 > 0.990) in then range from 1 to 200 ng/mL. The limit of detection（LOD, RS/N = 3）was 2.0 μg/kg and the limit of quantitation (LOQ, RS/N = 10）was 5 μg/kg. The recovery rate of the method for spiked samples was between 74.8% and 111.5% with relative standard deviation of 3.3%-9.0%. In general, the method was accurate, simple and reproducible and exhibited low background inference and it was thus suitable for the analysis of nonylphenol in liquid milk.

Human milk oligosaccharides (HMOs) are a group of complex glycans occurring in human breast milk that play important roles in the growth and development of infants. More than 200 distinct kinds of HMOs have been identified so far. The naturally occurring mixtures of HMOs in humans have different components and profiles that reflect the mother’s genetic makeup (e.g., Lewis blood type), duration of lactation, life style, diet and geographic region. A number of functions that may protect the health of breast-fed infants have been reviewed for HMOs. However, available information on the content and profiles of HMOs in human milk, especially among Chinese mothers, is limited. Therefore, further research on the relationship between the structure and functions of HMOs and a databank of HMOs from Chinese mothers are needed in order to establish a firm scientific basis and specific guidelines for improved infant formula in the future.

In January 2013, it was reported that dicyandiamide (DCD) residues were detected in New Zealand milk and milk products, which has received worldwide concern. Therefore, the development of methods to detect dicyandiamide in milk and dairy products has become a hot topic. In this paper, we review methods used to detect dicyandiamide in milk and dairy products such as HPLC-MS/MS, UPLC-MS/MS and UFLC-MS/MS, including sample extraction and purification, chromatographic column selection, mobile phase composition optimization, mass spectrometry monitoring mode and matrix effect of samples.

In this paper we review recent applications of high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), ultra high performance liquid chromatography coupled with high-resolution time-of-flight mass spectrometry (HRTOF-MS), and matrix assisted laser desorption ionization-Fourier transform ion cyclotron resonance mass spectrometry (MALDI-FTMS) to determine penicillin residues in milk and dairy products and their major enzymatic metabolites in vivo. This review describes recent progress in the development of sample extraction, purification, chromatographic separation and mass spectrometry detection methods for the determination of penicillin residues in dairy products.

In this study, the impact of adding different amounts of sodium bisulfate on the color change of sterilized processed cheese as indicated by L*, a* and b* values as well as ΔE (color difference) was investigated with the aim of solving the browning problem of processed cheese during sterilization. It was found that addition of 0.2–0.8 g/kg of sodium bisulfate showed good inhibition against the browning of sterilized processed cheese.

This study used a quadratic rotation-orthogonal composite experimental design with four independent variables at five levels each to establish optimal process conditions for industrial production of Mozzarella cheese. The process conditions investigated in this study included fermentation time, clotting time, whey pH and the amount of added NaCl. A regression model to optimize these process conditions was proposed and validated for its statistical significance. The optimal process conditions that provided the maximum yield of Mozzarella cheese (24.78%) were determined as follows: fermentation time 27.5 min, clotting time 37.5 min, whey pH 6.3, and addition of 2.07% NaCl. The resulting cheese had a nice flavor, a close, smooth and flexible texture and a homogeneous color and its fiber-drawing capacity, meltability and foaming properties were good. All these parameters were comparable to those of laboratory-made cheese and met the quality requirements for use in pizza. The optimized process parameters are suitable for large-batch production of Mozzarella cheese in industrial practice.

This study investigated the effect of addition of protein isolates from three different plants (pea, mung and soybean) on cheese properties to find the most suitable plant protein for application in cheese. Milk coagulation properties (coagulation time, curd strength and whey OD value) and textural properties (elasticity, cohesiveness and chewiness) were comparatively tested on the three cheese samples. Moreover, sensory evaluation was carried out fuzzy judgment as well. Results showed that pea protein isolate provided better quality of cheese than the other two protein isolates.