In this study, ion exchange chromatography was employed to prepare high-purity α-lactalbumin from whey protein powder obtained from raw cow’s milk by sequential membrane separation and spray drying. The results showed that α-lactalbumin constituted 21.04% of the true protein in the permeate obtained using a 50-nm pore-sized ceramic membrane with three-fold concentration, one cycle of microfiltration and two cycles of washing, which was higher than that obtained using a 100-nm pore-sized ceramic membrane (15.84%). The permeate was spray dried and separated by ion exchange chromatography. Good chromatographic separation of α-lactalbumin and β-lactoglobulin was achieved with increasing NaCl concentration from 0 to 0.5 mol/L at up to 10 column volumes, and 98.18% pure α-lactalbumin and 97.82% pure β-lactoglobulin were obtained. The results of this study provide support for the industrial preparation of high-purity α-lactalbumin.

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 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.

This paper presents a comparative analysis of regulations and standards relating to whey protein powder in China and other countries and regions including the United States, the European Union, Canada, Australia, New Zealand, Japan and South Korea with respect to product quality indicators, contaminants and mycotoxins, and microbial limits. The quality indexes in China’s standards for whey protein powder are similar to those in other countries despite differences in some requirements. There are no differences in the requirements on mycotoxin residues, while the types and limits of contaminants are quite different. There are also some differences in the items but no difference on the limits of microbiological requirements.

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.

In recent years, the addition of probiotics to milk powder has gradually become a research focus. In order to ensure the product quality and safety, a microbiological detection method for Lactobacillus fermentum CECT5716 in milk powder has been established. It was found that the population of Lactobacillus fermentum in milk powder could be accurately counted by spreading serial 10-fold dilutions in buffered peptone water (BPW) onto MRS plates and culturing them under anaerobic conditions at (36 ± 1) ℃ for (48 ± 2) h, with clear discrimination from inoculated bifidobacteria. This method was more suitable for counting Lactobacillus fermentum than the Chinese national standard method (GB 4789.35?2016), and had the advantages of high discrimination capacity, short culture time, simple operation, good repeatability, and high accuracy. This method also included 16S rDNA sequence analysis of the strain for its subsequent molecular identification. There was no significant difference in the accuracy of this method versus the national standard method in detecting 20 samples prepared in our laboratory (P = 0.127).

The residues of ochratoxin A, deoxynivalenol, aflatoxins B1 and zearalenone in dairy feeds were simultaneously detected using biochip array technology. The method accuracy, precision and reproducibility were evaluated. The results obtained that the correlation coefficient of the calibration curve for each analyte was greater than 0.99. The recoveries for quality control sample and negative sample at two spiked levels varied from 80% to 120%. The coefficient of variance (CV) was less than 15% for accuracy and reproducibility and was less than 10% for reproducibility. Compared with high performance liquid chromatography, this method gave consistent results with a simpler sample pretreatment procedure. In conclusion, the biochip array method was simple and accurate and it could provide an efficient and reliable tool for mass screening of samples.

Enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) allows gene amplification using primers designed based on ERIC, which are widely present in living organisms, yielding products that are useful to characterize the genomic structure. This method has been widely used in bacterial classification and research on the genetic relationship of strains because of its merits such as simplicity, ease of implementation, good repeatability and time saving. This paper reviews the background to bacterial classification research and the principle and characteristics of ERIC-PCR technique, and summarizes the advantages and disadvantages of ERIC-PCR technique in bacterial genotyping and recent progress in its application to genotype common food-borne pathogenic bacteria. At the same time, future prospects for the application of ERIC-PCR in traceability analysis of microbial contaminants in dairy enterprises.

Nowadays, the Chinese dairy industry is developing fast. Dairy products have become an important part in people’s dietary structure. Functional dairy products are an emerging type of dairy products which exerts physiological effects through added probiotics and bioactive molecules. The present article presents an overview of China’s dairy products market and analyzes the classification, market and consumption conditions, current status and limitations of functional dairy products. Moreover, some suggestions regarding the development trends of functional dairy products in China are given based on the development of related products and technologies worldwide. This paper can provide useful references for the research and development of functional dairy products.

Lactoferrin is an important multifunctional protein that has a variety of biological activities, such as anti-bacterial, anti-tumor, anti-allergy, immunoregulatory and so on. The related basic research and application development of lactoferrin have attracted wide attention. Therefore, the detection methods for lactoferrin have drawn increasing attention. Especially the advantages, sensitivity, accuracy and stability of different methods vary to different extents, which directly affects their applicable scope. The present paper has described the detection methods which have been reported to be suitable for different types of biological samples, mainly including spectrophotometry, high performance liquid chromatography (HPLC), enzyme-linked immunosorbent assay (ELISA), high affinity chromatography (HPAC), efficient capillary electrophoresis (HPCE) and surface plasmon resonance (SPR). The advantages and disadvantages of these different detection technologies also have been analyzed and compared. This review is expected to provide reference for selection of the suitable detection method for lactoferrin in research and development practices.

The solubility of milk protein concentrate (MPC), which has a direct impact on its application value, may be reduced during storage. The effect of ultrasonic treatment with different powers for different durations on the solubility of fresh and stored MPC was studied. The results showed when stored MPC85, a commercial product, was treated with ultrasonic (at 50, 300 or 600 W for 5 min, or at 300 W for 3, 5 or 10 min), its solubility decreased sharply. As for fresh MPC70 stored for 30 d after treated with ultrasonic (at 300 or 600 W for 3, 5 and 10 min, respectively), its solubility decreased slowly and the smallest decrease was observed upon ultrasonic treatment for 300 W, 10 min. Ultrasonic treatment is useful to retard the decrease in the solubility during storage of MPC.

In the present study, a preliminary purification was carried out to obtain heat-resistant lipase secreted by Pseudomonas fluorescens separated from fresh milk. Moreover, the effects of temperature, pH, and Ca2+ concentration on the activity of this lipase were determined. Results showed that the lipase from Pseudomonas fluorescens had a molecular weight 55 kD and a purity of 91.5% after the purification, and its relative activity was 75.02%, 86.21%, 73.25%, 17.62% and 13.63% after heat treatment at 50 ℃ for 30 min, 63 ℃ for 30 min, 72 ℃ for 20 s, 90 ℃ for 10 min, and 121℃, 0.1 MPa for 20 min, respectively. The optimum reaction pH and temperature for this enzyme were 8.0 and 63 ℃, respectively. The lipase activity was not significantly affected by Ca2+ concentration.

This report describes an ion chromatography method for determining thiocyanate in dairy products. Milk samples were deproteinized by adding acetonitrile followed by centrifugation, microporous filtration and chromatography on LC-C18 SPE column. The analyte was monitored by ion chromatography. The optimized mobile phase consisted of 1.7 mmol/L sodium bicarbonate, 1.8 mmol/L sodium carbonate and 10% aqueous acetone solution. The suppressor was activated and regenerated with 0.2% sulfuric acid as an inhibitor. The detection limit for thiocyanate was 2.0 mg/kg, and the standard curve exhibited a correlation coefficient above 0.99 in the linear range of 0.1–20 mg/kg (mg/L). Recovery rates for spiked samples ranged from 93% to 97%, and repeatability expressed as relative standard deviation varied between 0.8% and 1.34% (n = 5). The detection accuracy for milk powder standard was 98%. The presented method was characteristic of easy operation, accurate and repeatable results and low detection limit, and was useful for the determination of thiocyanate in dairy products.

This paper is about the detection the four serotypes A, B, E and F of Clostridium botulinum from milk powder and whey powder by using real-time fluorescent quantitative PCR method (RT-PCR). The standard curves for blends of serotypes A and B as well as of E and F were established using the original positive control from a commercial RT-PCR kit and its 10, 102, 103 and 104-fold dilutions. The cycle threshold (Ct) values exhibited excellent specificity, repeatability and accuracy. By using the method, none of these four serotypes was detected in 82 samples milk power and whey power with suspected strains as confirmed by the Chinese national standard and the industry standard of entry-exit inspection and quarantine.

A method for determining parabens and natamycin in dairy products by HPLC is described. Samples were extracted with methanol and separated on a C18 column with methanol-acetic acid solution as mobile phase. UV detection was performed at 256 nm and 305 nm. Complete separation of pimaricin and four parabens, methyl 4-hydroxybenzoate, ethyl 4-hydroxybenzoate, propyl 4-hydroxybenzoate and butyl 4-hydroxybenzoate was achieved within 35 min. Under optimized conditions, the linear ranges for the food antiseptics was 1–100 mg/kg with a correlation coefficient greater than 0.9990, and their average recovery rates from blank real samples spiked at three different levels was between 83.7% and 103%. This method was simple, rapid and accurate.