Lactiplantibacillus plantarum is widely used in the food fermentation, breeding and healthcare fields. It has the ability to produce high yields of acid and biological preservatives, and has beneficial effects such as immune regulation, maintaining intestinal health, and inhibiting pathogenic bacteria and tumor cell formation. Some strains of L. plantarum promote the release of plant-based bioactive ingredients and improve the biological activity and nutritional properties of plant-based foods. L. plantarum fermented foods have a unique flavor, and their nutritional components are maintained and even enhanced, which is beneficial to human health. In order to provide a reference for further research and application of L. plantarum, this article summarizes the mechanism of action of L. plantarum in promoting the release of bioactive substances, the current status of its application in fermented foods, its health effects, and new omics research approaches for L. plantarum.

During storage, milk is prone to different degrees of oxidative degradation of fat with varying storage conditions, which changes the aroma components of milk. In this study, electronic nose based on gas chromatography (GC) and sensory evaluation were used to compare the changes in the composition of volatile flavor compounds and sensory properties of pasteurized whole milk, low-fat milk and skim milk (fat contents of 4, 1.4 and 0 g/100 mL) during storage at different temperatures. The results showed that all three milks maintained good flavor characteristics during storage at 4 ℃. The composition of flavor substances in whole milk was more complex, where 43 volatile compounds were identified, and no obvious stale flavor was perceived. The decreasing order of difficulty of fat oxidation was whole milk > low-fat milk > skim milk. Nonanal, a marker of lipid oxidation, was detected in both skim milk and low-fat milk. Methyl ketones derived from lipid oxidization such as 2-butanone, 2,3-butanedione, 2-hexanone, 2-heptanone and 2-undecanone were detected in skim milk during storage. The results of sensory evaluation were basically consistent with those of electronic nose. The sweetness and milky flavor of whole milk were more prominent, the flavor of low-fat milk was relatively bland, and skim milk tasted slightly bitter after 21 days of storage at 25 ℃. The findings of this study will provide a scientific basis for monitoring the flavor changes of milk products during storage and improving the quality of milk products.

Probiotic fermented dairy products are rich in beneficial microorganisms such as lactic acid bacteria as well as a variety of bioactive substances, conferring multiple health benefits to consumers. This paper reviews the latest research developments in probiotic fermented dairy products, including the types and functions of probiotics and their roles in treating inflammatory bowel disease, improving obesity, enhancing cognitive function, alleviating allergic symptoms, maintaining bone health, combating constipation, lowering cholesterol, and managing diabetes. The paper concludes with a summary and outlook on the future development directions of probiotic fermented dairy products, highlighting the importance of the development, clinical testing and market exploitation of personalized products. It is hoped that this review will lay a theoretical foundation for further research into probiotic fermented dairy products.

Citrus fiber is a kind of natural dietary fiber extracted from the peel of citrus fruits. It has many physiological functions such as lowering blood sugar, lowering blood lipid and regulating intestinal balance. The internal structure, physicochemical properties and processing properties of citrus fibers from different citrus fruits are different. At present, the commonly used extraction processes include physical, chemical and biological methods. How to improve the yield of the final product has always been a difficulty faced by the citrus industry. Citrus fiber has excellent water-holding capacity (WHC), emulsifying capacity and apparent viscosity, and it is widely used in the processing of dairy products. In addition, citrus fiber plays an irreplaceable role in the development of clean-label dairy products. This paper reviews the physicochemical properties, extraction processes and application in dairy products of citrus fiber, which is of reference significance for the research and application of citrus fiber.

The separation of ingredients from raw milk is an essential step during the production of dairy products. Membrane separation technology has been applied in the dairy processing industry for decades and has increasingly become indispensable in solving some problems such as separation, concentration, sterilization and in developing new dairy products. In this paper, the main applications of membrane separation technology in the dairy industry, including milk standardization, protein separation, whey desalination and waste water utilization are reviewed, in order to provide reference for process selection and optimization.

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.

The applicability of enzyme colorimetry as specified in the National Food Safety Standard: Determination of Choline in Infant Food and Milk Products (GB 5413.20－2013) for the determination of choline in infant formula for special medical purposes was evaluated using quality control and actual samples as well as spiked recovery and precision tests. The theoretical value of choline content in quality control samples was 171.5 mg/100 g, and the measured value was 168.4 mg/100 g. The measured result was within the allowable error range indicating its reliability. Spiked recoveries for infant formula and quality control samples were 96.1%–98.4% with relative standard deviation (RSD) of 1.43%, indicating high accuracy and precision of the method. When the method was applied to 24 batches of commercial samples, the measured values of choline content met the requirements of the national standard. Accordingly, enzyme colorimetry can be used to detect choline i n infant formula for special medical purposes.

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.

A method to test the opening force for cover film sealed yogurt plastic cups was put forward by quantifying the opening force using special force testing equipment to completely simulate human-machine operations, which is mainly characterized by the initial opening force and the continuous opening force. Commercial yoghurt packagings consisting of different combinations of two plastic cups made from polypropylene (PP) and polystyrene (PS) with aluminum foil composite film, aluminizer composite film and embossing aluminum sheet were tested using the method in this study, and the ranges of opening force for them were obtained. The results showed that the initial opening force was significantly greater than the continuous opening force; the initial opening force for PS and PP cups was 10–25 N, and the continuous opening force was more than 10 N for the cups sealed with embossing aluminum sheet, whereas for the cups sealed with aluminumplastic composite film it was only 4–8 N. For cups sealed with the same films, the opening force for PS cups was higher than for PP cups. Moreover, the initial opening force for cups sealed with aluminizer composite film was greater than for those made from the same material and sealed with the two other films, and the continuous opening force was significantly increased for cups sealed with embossing aluminum sheet compared with those sealed with the other films. There was a significantly smaller difference between the initial and the continuous opening force for embossing aluminum sheet, and the sealing intensity from it was more stable.

This study aimed at the application of Wolf formula for structural design of corrugated box for dairy products. Five kinds of corrugated boxes for 350 mL of Momchilovtsi, a Bright Dairy yoghurt brand, were designed according to the capacity and arrangement of the inner packaging, and their theoretical compression strength was calculated using Wolf formula as well as their minimum compression strength when 10 boxes were stacked and stored in the same environment using compression formula. Comparative analysis of the results of both calculations was carried out based on structural design elements such as ratio of length to width and length of sides. Moreover, verification was achieved using compression tests. Finally, we established the optimal structural design of 350 mL corrugated boxes for Momchilovtsi. It was showed that corrugated carton No. 4 had the highest marketability under the conditions: the same material and height, 3 × 3 arrangement mode, length/width ratio of 1, and length of sides of 74 mm.

Three kinds of aluminum-free composite sealing film: F1, polyethylene/low density polyethylene/ethylenevinyl acetate copolymer (PE/LDPE/EVA); F2, polyethylene terephthalate (PET)/PE/EVA; and F3, PET/cast polypropylene (CPP)/ EVA were selected to package yoghurt in polystyrene (PS) cups. Comparison of material characteristics and packaging performance of composite films and the storage life of packaged yoghurt was carried out with respect to fim oxygen permeability, opening force and puncture resistance, and yoghurt sensory evaluation, acidity and storage life. The storage life of yoghurts packaged with F1, F2 and F3 was tested at (30.0 ± 1.5), (25.0 ± 1.5) and (4.0 ± 1.5) ℃, respectively. The results showed that oxygen permeability of F3 was the lowest, 46.602 cm3/(m2·24 h·0.1 MPa), among three kinds of films at the same temperature and humidity, and it had the best oxygen barrier property, while oxygen barrier property of F1 was the lowest. The storage temperature of (4.0 ± 1.5）℃ had less significant impact on the sensory evaluation, acidity or storage life of yoghurt than (30.0 ± 1.5) and (25.0 ± 1.5) ℃ and gave the longest storage life of 7 to 8 days, yielding an acidity higher than 87 °T at the end of the storage life. Under the same storage conditiuons (time and temperature), yoghurt packaged with F3 had the lowest acidity and exhibited the loweest growth rate of acidity and the best sensory evaluation results. In terms of opening force, only F2 and F3 met the packaing requirements for yoghurt. F1 had very high puncture resistance while F3 was the easiest to puncture with an ease level of 85%. Together, the above fingdings demonstrate that PET/CPP/EVA film is the most suitable sealing film for packaging yoghurt in cups, which achieves the longest storage life of 8 days at (4.0 ± 1.5) ℃ and meets the packaging requirements for yoghurt.