Goat’s milk contains a rich variety of oligosaccharides with various physiological functions, and its content and structure are close to those of human milk oligosaccharides. Goat’s milk can be regarded as a natural alternative source of human milk oligosaccharides with potential applications in the food field. This paper briefly introduces the composition, content and structure of oligosaccharides in goat’s milk, analyzes the factors affecting the composition and content of oligosaccharides in goat’s milk, and focuses on the comparison of various preparation methods such as membrane separation, chromatography and biosynthesis. In addition, the pre-treatment methods for and the characteristics of different techniques for the detection of goat’s milk oligosaccharides are summarized, and finally, the probiotic functions of goat’s milk oligosaccharides as well as the prospects and challenges for their application in the future research are discussed. Finally, the probiotic functions of goat’s milk oligosaccharides and future prospects and challenges for their research and application are discussed.

The optimal parameters for ultrasonic-assisted enzymatic extraction of polysaccharides from Potentilla anserina L. using a mixture of cellulase, pectinase and papain (2:1:0.5) were determined as follows: enzyme dosage 49 U/g, ultrasonic time 100 min and pH 4.4. Under these conditions, the maximum yield of polysaccharide extract from Potentilla anserina L. (PAPE) of (6.89 ± 0.08)% was obtained. Furthermore, the effect of PAPE on yak yoghurt fermentation was investigated. The results showed that PAPE could significantly enhance the viable count and acid-producing capacity of Streptococcus thermophilus CICC 6038, Lactobacillus bulgaricus CICC 20247 and Lactobacillus fermentum HY01 in a dose-dependent manner. Yoghurt added with PAPE at 2 g/100 mL concentration had a hardness of (163.0 ± 9.9) g, a viscosity of (?182.9 ± 1.6) g·s, a consistency of (69.7 ± 1.7) g·s, a cohesiveness of (410.0 ± 6.0) g and it had a good taste, with a sensory score of 7.78; its antioxidant capacity in terms of scavenging capacity against hydroxyl, superoxide anion and 2,2’-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) cation radicals increased significantly compared with the control group. This study provides new ideas for improving the quality and added value of yak yogurt.

An inductively coupled plasma-tandem mass spectrometry (ICP-MS/MS) method was established for the analysis of 26 inorganic elements in dairy products. Under MS/MS conditions, the 26 elements were detected in the no gas, collision gas (He) or reaction gas (H2, O2, NH3/He) mode and the optimal mode was selected for each of the elements. The results showed that calibration curve with good linearity was obtained for each element in the appropriate detection mode with a correlation coefficient greater than 0.999 0. The detection limits of the 26 inorganic elements ranged from 0.000 033 61 to 0.043 71 mg/kg. The spiked recoveries were between 95.50% and 104.21%, with a relative standard deviation (RSD) ≤ 3.94% (n = 11). The contents of Na, Mg, K, Ca, P, Fe and Zn were higher and the contents of the heavy metal elements Cr, As, Cd and Pb were lower in six kinds of dairy products, all of which were lower than the national standard limits. The method was characterized by simple pretreatment, high sensitivity, low limit of detection and high accuracy and could be used for the detection of inorganic elements in dairy products.

The proteases in cow’s milk have a great influence on the flavor and quality, especially on the shelf life of dairy products, but there is no uniform reference standard for the detection of protease activity in dairy products. This paper elaborates the sources, types and characteristics of protease in cow’s milk, and summarizes recent progress in the detection of the activity of different types of protease in cow’s milk, pointing out that the precise detection of protease activity in milk has great significance for dairy production and quality assurance.

With the development of China, children’s cheese has garnered increasing attention in the dairy industry, which has become a new growth point of China’s dairy industry. However, children’s cheeses currently available on the market are uneven, which cannot be fortified completely according to children’s nutritional needs. Their tastes are similar and their selling points are the same, which causes the public’s sensory fatigue and also go against consumers’ pursuit of clean label. Thus, the development of the children’s cheese industry is facing new challenges. In this paper, from the perspectives of children’s health and cheese nutrition, we link the needs of children of different ages for nutrition, flavor and texture with the nutrition, flavor and texture of cheese. The present situation, challenges and possible development directions of children’s cheese food in China are summarized.

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.

Abnormal analysis of trace elements and heavy metal over-standard in dairy products are major concerns in the dairy industry, and how to detect elements of concern in dairy products quickly and accurately has become the focus of attention. Detection of elements in milk and dairy products is a prerequisite to ensure product quality and safety. Therefore, the pretreatment and detection methods specified in the Chinese and international standards for elements in milk and dairy products are reviewed. The principle, pros and cons of each method are elaborated so as to provide a reference for the detection of elements in the dairy industry.

A method for the determination of stevioside, rebaudioside A, rebaudioside B, rebaudioside C, rebaudioside F, dulcoside A, rubusoside and steviolbioside in fermented milk by high performance liquid chromatography (HPLC) was developed and validated. The chromatographic conditions and sample pretreatment conditions were optimized. Samples were ultrasonically extracted with water for 20 min and for another 10 min after addition of 30% acetonitrile in water bath at 45 ℃. Potassium ferrocyanide and zinc acetate were added to precipitate proteins. The chromatographic separation was achieved on a C18 with gradient elution using a mobile phase consisting of sodium phosphate buffer and acetonitrile, and the analytes were detected by an ultraviolet (UV) detector at 210 nm. The results showed that the method was linear in the concentration range of 1–50 μg/mL, the limit of detection (LOD, RS/N = 3) was 3.0 mg/kg, and the limit of quantitation (LOQ, RS/N = 10) was 10.0 mg/kg. The average recoveries of all analytes spiked at 15–200 mg/kg were between 92.0% and 103.1%, with relative standard deviation (RSDs) (n = 6) less than 3.0%. This method was rapid, accurate, stable, sensitive, and suitable for the analysis of the content of steviol glycosides in fermented milk.

To establish a method for simultaneous detection of 17 mycotoxins in milk and dairy products based on high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Samples (5.000 0 g) were added to 20 μL of a mixed solution of isotope-labeled internal standards, extracted with 20 mL of acetonitrile-water-formic acid solution (70:29:1, V/V) by vortex shaking, salted out with 0.3 g of sodium chloride, and then centrifuged at high speed. The supernatant was passed through a 0.22 μm membrane filter, detected by triple quadrupole mass spectrometry in the multi-reaction detection mode and quantified by an internal standard method. Results: Under the optimized instrumental conditions, good linearity was observed for the 17 mycotoxins in the tested concentration ranges, with correlation coefficient (r) greater than 0.99. The limit of detection (LOD) was 0.05-6.20 μg/kg, and the limit of quantitation (LOQ) was 0.2-20.0 μg/kg. Good average recoveries (78.9%-119.5%) and precision (relative standard deviations (RSDs) 0.2%–8.4%) were achieved at three spiked levels. The method is convenient, stable, reliable and sensitive, can meet the requirements of qualitative and quantitative analysis of the 17 mycotoxins in milk and dairy products, and is suitable for laboratory monitoring of the contamination of these mycotoxins in milk and dairy products.

A reversed-phase high performance liquid chromatography (RP-HPLC) method was established for the determination of 6S-5-methyltetrahydrofolate calcium in milk powder. After protein precipitation with trichloroacetic acid solution, samples were extracted with ascorbic acid solution in a hot water bath, and the extract was separated on a C18 reversed-phase column by gradient elution using a mobile phase composed of 0.1% trifluoroacetic acid solution and methanol, and the detection wavelength was set at 280 nm. Quantitative analysis was carried out by the single standard method. The results showed that the limit of quantification and detection of 6S-5-methyltetrahydrofolate calcium in milk powder samples were 150 and 50 μg/100 g, respectively. The recoveries for samples spiked at levels ranging from 150 to 600 μg/100 g were 95.0%–109.1% with relative standard deviations (RSDs) between 1.26% and 4.04%. This method is simple, accurate, with high recovery and reproducibility, and suitable for the determination of 6S-5-methyltetrahydrofolate calcium in milk powder.

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.

Being rich in nutrients, dairy products provide a good environment for the growth of Staphylococcus aureus, Salmonella, Listeria monocytogenes, Cronobacter and other foodborne pathogens, which poses a serious threat to the safety of dairy products. Therefore, rapid and accurate detection of foodborne pathogens in dairy products is essential to the prevention of foodborne pathogens. In recent years, analytical techniques including molecular biology and immunoassays have rapidly developed and attracted much attention due to their advantages of high sensitivity, rapidity and simplicity compared with the traditional food pathogen detection methods, which are cumbersome and time-consuming. In this paper, recent developments and applications of foodborne pathogen detection techniques are reviewed, and future trends were discussed in order to provide a reference for the rapid detection of foodborne pathogens in dairy products.

A reversed-phase high performance liquid chromatographic (HPLC) method was established for the determination of erythrosine in fermented milk. After enzymatic hydrolysis, the sample was extracted with anhydrous ethanol, and purified by solid phase extraction using an HLB column under alkaline conditions. The separation was performed on a C18 reversephase column by gradient elution using a mobile phase comprising 20 mmol/L ammonium acetate buffer solution (pH 6.5) and methanol. The detection wavelength was set at 520 nm, and quantification was performed by the external standard method. The results showed that the linear range for erythrosine was 0.05–20.00 μg/mL. The limit of quantitation (LOQ) and the limit of detection (LOD) of erythrosine in fermented milk samples were 0.2 and 0.1 mg/kg, respectively. The recoveries from fermented milk samples spiked at levels of 0.2–2.0 mg/kg were 96.5%–105.6%, and the relative standard deviations (RSD) were 1.87%–2.21%. The method is simple and accurate, has high recovery and good repeatability, and is suitable for the determination of erythrosine in fermented milk.

In this study, the effect of addition of water-insoluble dietary fiber (IDF) enzymatically extracted from Auricularia auricula on the acidity and viable bacterial count of fermented milk was explored. One-factor-at-a-time method combined with orthogonal array design was used to optimize the formulation (concentrations of IDF, skim milk powder and sodium carboxymethyl cellulose) of fermented milk with added IDF based on sensory evaluation score. The nutrient composition and texture characteristics of the fermented milk prepared using optimized formulation were determined. The results showed that IDF from Auricularia auricula could promote the proliferation of lactic acid bacteria. The optimum formulation consisted of 7% IDF (converted into 0.78% freeze-dried powder) 1.5% sodium carboxymethylcellulose and 2.0% skim milk powder. The prepared fermented milk contained (3.53 ± 0.08)% protein, (3.12 ± 0.03)% fat, (0.78 ± 0.12)% ash, and (19.35 ± 0.49)% solids. Addition of IDF improved the water-holding capacity, hardness, chewiness and viscosity of fermented milk during storage and at the same time showed a protective effect on the starter culture.

The measurement uncertainty was estimated for the determination of 1-oleic-2-palmitic-3-linoleic acid triglyceride (OPL) content in milk powder by gas chromatography (GC). According to the Measurement and Expression of Uncertainty in Measurement (JJF 1059.1—2012) and the Guidance on Quantifying Uncertainty in Chemical Analysis (CNAS-GL 006: 2019), a mathematical model was established to analyze the sources of measurement uncertainty. The major factors affecting the measurement uncertainty were evaluated. Results showed that the average OPL content of six milk powder samples was measured to be 1.172 g/100 g. The relative expanded uncertainty (urel) was 0.023 6 with a coverage probability of approximately 95%. The standard uncertainty arising from sample preparation was the main source of uncertainty.

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.

A small amount of bacterial spores with strong tolerance still exist in raw milk after sterilization and can multiply under certain conditions, causing a serious impact on product quality and consumer health. In this study, raw milk samples containing Bacillus were collected to isolate aerobic Bacillus and thermophilic aerobic Bacillus. The isolates obtained were identified based on their morphological, physiological, biochemical and molecular biological characteristics, and the heat resistance of the isolated thermophilic aerobic Bacillus was studied. Results showed that 10 strains of Bacillus were isolated from the milk samples, of which three were thermophilic aerobic Bacillus and seven were aerobic Bacillus. Among them, Bacillus coagulans and Bacillus clausii could tolerate heat treatment at 115 ℃ for 15 min. All Bacillus in raw milk could be killed by heat treatment at 121 ℃ for 20 min which decreased the number of spores by four orders of magnitude. The dominant Bacillus species in raw milk were Bacillus subtilis, Bacillus cereus, Bacillus pumilus, Bacillus licheniformis, Bacillus circulans, Bacillus gelatini, Bacillus amyloliquefaciens, Bacillus coagulans, and Bacillus clausii. Bacillus coagulans and Bacillus clausii had stronger heat resistance and could tolerate heat treatment at 115 ℃ for 15 min.

A high performance liquid chromatographic (HPLC) method was developed for the determination of naringin in milk and dairy products. Samples were extracted with methanol, and the analytes were separated on a C18 column using a mobile phase consisting of 0.1% acetic acid aqueous solution and acetonitrile (75:25, V/V), detected by a diode array detector at 284 nm and quantified by an external standard method. The results showed that the linearity of this method was good in the concentration range of 5–500 μg/mL with a correlation coefficient of 0.999 9. The recoveries of powdered and liquid milk power and yogurt spiked at 0.02, 0.04, and 0.08 g/100 g were 96.2%–103.2%, 96.3%–103.7%, and 99.7%–104.1%, respectively, with relative standard deviations (n = 6) of 1.12%–2.31%, 1.25%–1.85%, and 1.24%–1.66%, respectively. The reported method is simple, rapid, accurate, repeatable, and suitable for the determination of naringin in milk and dairy products.

A gas chromatographic (GC) method for the determination of 1-oleic-2-palmitic-3-linoleic-triglyceride (OPL) in milk powder was established. The samples were extracted with ether and petroleum ether, and the extract was concentrated to near dryness, re-dissolved in n-heptane, separated on a CP-TAP CB elastic quartz capillary column, detected by a hydrogen flame ionization detector, and quantified by an external standard method. The column temperature was programmed to rise. The inlet temperature was set at 330 ℃. The samples (1.0 μL) were injected using the split mode (1:10). The detector temperature was set at 360 ℃. Nitrogen was used as the carrier gas. The makeup flow rate (nitrogen) was 25 mL/min. The recovery of OPL from spiked milk powder at 1–6 g/100 g ranged from 95.2% to 101.9%, and the relative standard deviations (RSDs) for precision ranged from 1.289% to 1.998%. The limit of detection (LOD) and limit of quantitation (LOQ) of the proposed method were 0.2 and 1.0 g/100 g, respectively. This method, therefore, is simple, accurate, repeatable, and suitable for the determination of OPL in milk powder.

To investigate the pollution status of eight harmful elements in milk fan and milk cakes. Milk fan and milk cake were sampled from representative farmers’ markets and supermarkets in some districts or counties of a certain city. The samples were digested by a wet digestion method using graphite, and eight harmful elements including arsenic, lead, mercury, cadmium, chromium, boron, aluminum and barium in the digested samples were simultaneously detected by inductively coupled plasma mass spectrometry (ICP-MS) and quantified by an internal standard method. Neither milk fan nor milk cake samples were found to be contaminated by mercury or cadmium, and the contamination levels of boron, arsenic, barium and lead was relatively low; however, the milk fan samples were seriously polluted by aluminum and chromium, and the contamination level of barium in milk cakes was relatively high. Both milk fan and milk cake samples contained chromium, barium and lead, and the contamination level of the former was higher than that of the latter. Accordingly, relevant departments should strengthen supervision over milk fan and milk cake workshops, standardize the production processes, strictly control the potential pollution links, and strengthen supervision over pollution in the production process to ensure product quality and safety.

Sample pretreatment is a key step in element testing, which directly affects the precision and accuracy of analytical results. In order to meet the requirements for the detection of various elements, in this study, we used microwave digestion combined with inductively coupled plasma-mass spectrometry (ICP-MS) operated in the collision reaction mode to determine the content of multiple elements in milk powder, and investigated the influence of sample pretreatment conditions (acid removal time, sample size, and the amount of residual acid) on the detection results. Compared to removing acid mist only, better results were obtained under the following conditions: acid removal temperature was 160 ℃, acid removal time was 97.5 min, and sample size was 0.250 0 g, and the amount of residual acid was 1.0 mL. This pretreatment process is characterized by good stability, high precision and high accuracy.

Inductively coupled plasma-mass spectrometry (ICP-MS) was used to measure the aluminum content in the quality control sample of milk powder, and an X-control chart was established for runaway judgement and handling during the operation process. The precision and median line of the control chart for new data points obtained one year later were evaluated using Minitab software with test for equal variance and analysis of variance. The standard deviation for the previous 25 data points was 0.186 mg/kg compared to 0.126 mg/kg for the 35 new ones, while the median values of the two groups did not differ from each other. More reliable control limit was calculated based on all the data points, and the new median value was 1.334 mg/kg with a standard deviation of 0.154 mg/kg. The decrease in standard deviation suggested that the precision was improved with smaller data fluctuations. In conclusion, calculation of new and more reliable control limit from more data is useful to find obvious systematic errors, abnormal data and slow changing trend in a timely and effective way and can provide evidence to decide whether data should be retained or removed so as to directly reflect the stability and tendency of the detection.

A gas chromatographic (GC) method to determine the contents of 16 trans fatty acids in ice cream was established. The 2.0 g samples were pretreated sequentially with 8 mL of hydrochloric acid and 10 mL of anhydrous ethanol, separated on an SP-2560 capillary column, detected by GC with a flame ionization detector (FID) and quantified by the peak area normalization method. Under optimized chromatographic conditions, the limit of detection and limit of quantification of the proposed method were 0.012% and 0.024%, respectively, and it allowed effective separation of trans fatty acid methyl esters from cis fatty acid methyl esters and saturated fatty acid methyl esters.

Iodine is an important index of the nutritional quality of milk. Milk and dairy products are important dietary sources of iodine for humans, which has always aroused extensive concern. With the continuous exploration of nutrients in foods, research on iodine in milk has been increasingly intensified and refined. This paper reviews the recent literature on the factors that affects the iodine content of milk and the analytical methods that have been applied to determine it, which is expected to provide a reference for researchers in this industry and also provide a theoretical basis for the labelling of iodine in infant formula preparation.

In order to provide a scientific rationale for the quality control in the determination of aerobic plate count (APC) in milk, the measurement uncertainty was estimated. According to the national standard of China (GB 4789.2—2016), APC in samples was detected. The sources of uncertainty were analyzed according to Evaluation and Expression of Uncertainty in Measurement (JJF 1059.1—2012) and a mathematical model for uncertainty evaluation was established. The introduced uncertainty components were evaluated and finally the total combined uncertainty was established by combination of individual components. The results showed that the extended uncertainty for APC quantification in milk samples was 0.043 4. The logarithm of APC was [3.924, 4.010], and from this, APC was calculated to be 8 395–10 233 CFU/mL. In conclusion, this procedure can effectively assess the measurement uncertainty in the determination of APC in milk.

The detection of pesticide residues in dairy products is an important measure to ensure the quality and safety of dairy products. Currently, QuEChERS (quick, easy, cheap, effective, rugged, safe) is widely used as a sample pretreatment for all existing methods specified in the national standards for the detection of pesticide residues in dairy products. In this paper, we review these methods with a special focus on the principle and advantages of QuEChERS as well as its application in the detection of pesticide residues in dairy products.

In order to develop a new method to determine nitrite and nitrate in milk and milk products, some improvements were made on the ion chromatography method specified in the national standard GB 5009.33-2016 Determination of Nitrite and Nitrate in Food. Samples were extracted with ultra-pure water and added with acetic acid to precipitate proteins before being chromatographed on AS11-HC column and detected with a conductivity detector. Under the above conditions, the calibration curves for nitrite and nitrate were linear with correlation coefficients greater than 0.99. The limit of quantitation (LOQ) for nitrite and nitrate was 0.25 and 0.8 mg/kg in milk, and 1 and 5 mg/kg in milk powder, respectively. The recoveries for spiked samples of milk powder and milk were from 80% to 110%. The improved method was simple to operate and cheap with ideal recovery and high precision. It could avoid potential problems encountered in the use of the traditional method and allow for more rapid and accurate detection of low contents of nitrite and nitrate in milk and milk products.

A method for the determination of zeaxanthin in milk powder was developed using high performance liquid chromatography (HPLC). The sample was saponified with potassium hydroxide solution to release zeaxanthin, extracted with a mixed solvent of ethyl ether, n-hexane and cyclohexane and frozen for degreasing. The chromatographic separation was performed on a C30 column with gradient elution. The analyte was detected with an ultraviolet detector and quantified by an external standard method. The limit of quantification was 100 μg/100 g and the limit of detection was 30 μg/100 g for zeaxanthin in milk powder. The method recoveries at spiked concentration levels of 90–811 μg/100 g were 85.8%–102.2%, with relative standard deviations ranging from 1.43% to 2.76%. This method was accurate, repeatable, precise and sensitive.

A spectrophotometric method for the determination of tea polyphenols in milk tea powder was developed by using Folin-phenol reagent. Crucial operating parameters such as extraction reagent, number of extraction cycles, temperature and derivatization reagent were investigated. Extraction using 70% methanol solution as the extraction reagent in a hot water bath at 70 ℃ performed twice and oxidization of the resulting extract with Folin-phenol reagent proved optimal. The detection wavelength was selected as 765 nm, and gallic acid was used as the calibration standard for the quantitation of tea polyphenols. The recoveries for whole milk powder spiked at concentration levels of 850–4 500 mg/kg were in the range of 98.9%–104.9%. Good stability and accuracy were achieved. When milk tea powder samples with different contents of tea polyphenols were detected in six replicates, relative standard deviations (RSDs) of 0.29%–0.84% were obtained, indicating good precision. This method proved to be accurate, easy to operate and repeatable with simple and easily available instruments, and thus suitable for the analysis of tea polyphenols in milk tea powder.

By analyzing some factors involved in the determination of lead in milk powder by inductively coupled plasma mass spectrometry (ICP-MS) such as containers and reagents used, an ultrasonic cleaning method was established to effectively reduce the blank value. The method gave a detection limit of 0.005 mg/kg, which was much lower than that (0.02 mg/kg) of traditional methods. The recoveries of samples spiked at concentration levels of 0.005–0.015 mg/kg ranged from 86.9% to 119.0% with relative standard deviations (RSDs) of 3.1%–12.3%, meeting the requirements for methodological validation. Hence, the method proved to be overall feasible and suitable for the detection of lead in milk powder with reduced detection limit.