Table of Content

01 March 2026, Volume 49 Issue 2

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Basic Research

Bacterial Diversity Analysis of Bactrian Camel Raw Milk and Breeding Environment

WANG Wanxing, LUO Shengjin, YOU Wenbing, LI Wencai, Adila·Shadeer, PAN Yiwei

2026, 49(2):  1-8.  DOI: 10.7506/rykxyjs1671-5187-20251028-072

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This study aimed to use 16S rRNA gene sequencing to explore the structure and diversity of bacterial communities in Bactrian camel (Camelus bactrianus) raw milk (individual raw milk samples, mixed samples from temporary storage tanks, and cooled milk samples from tanker trucks) and environmental samples (feed, forage grass, and bedding soil) from three camel farming cooperatives in Hami, Xinjiang (six samples each). The results showed that a total of 4 102 198 raw sequences, 3 482 896 valid sequences and 66 514 amplicon sequence variants were obtained from the 18 samples. Significant differences existed in the composition of microbial communities between the raw milk and environmental samples. The dominant bacterial phylum in the raw milk samples was Pseudomonadaceae (37.36%), followed by Bacteroidetes (31.65%) and Bacillota (22.92%); whereas in the environmental samples, the dominant bacterial phylum was Firmicutes (38.27%), followed by Cyanobacteriota (36.34%) and Pseudomonadaceae (14.21%). These findings indicate that camel milk is at risk of bacterial contamination during collection and storage, and feedstuffs and forages can serve as temporary bacterial reservoirs. Milking procedures and the hygiene of the breeding environment are two key factors affecting raw milk quality, which require focused attention in practical production.

Analysis & Detection

Establishment of a Rapid Identification Method for Three Common Foodborne Gram-Negative Bacteria Based on Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry

ZHANG Tao, ZHANG Rui, ZHANG Yalun, ZHANG Zilun, ZHANG Jie, ZHOU Wei

2026, 49(2):  9-18.  DOI: 10.7506/rykxyjs1671-5187-20251104-074

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This study aimed to establish a rapid method for identifying three common foodborne pathogenic Gram-negative bacteria (Vibrio parahaemolyticus, Enterobacter cloacae, and Acinetobacter baumannii). We explored the effects of different pretreatment methods, media, and culture durations on the results of bacterial identification using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). We optimized the MALDI-TOF/TOF MS (tandem TOF MS) method with respect to culture medium and time. Formic acid-acetonitrile extraction was found to be the most suitable pretreatment method. The single-stage TOF MS spectra showed significant differences in identification scores, the number of characteristic peaks, and morphology among strains grown on different media. The number of major ion peaks decreased with culture time, leading to reduced matching accuracy. The tandem TOF MS spectra showed no significant changes in the characteristic peaks of strains at different culture times, indicating that the tandem TOF MS method was less affected by the external environment, exhibiting higher specificity. The single-stage TOF MS method had high accuracy for identifying strains cultured in specific environments for short durations. However, as the culture environment changed and the culture time increased, the results of single-stage TOF MS became unstable, while those of tandem TOF MS changed little. When they were applied to identify Gram-negative bacteria, compared with single-stage TOF MS, tandem TOF MS gave more stable results with fewer interfering peaks, thereby serving as an effective supplement to the existing microbial identification methods.

Determination of 5-Hydroxymethylfurfural and Furfural Contents in Liquid Milk by High-Performance Liquid Chromatography

ZHAO Shuli, XU Hong, TANG Zhenxin, JI Helian, ZHANG Xuejiao, WANG Chen, GAO Wandong, ZHANG Caixia, WU Xiaoli

2026, 49(2):  19-23.  DOI: 10.7506/rykxyjs1671-5187-20251005-065

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A high-performance liquid chromatography method was developed to determine the contents of 5-hydroxymethylfurfural and furfural in liquid milk. The samples were extracted with oxalic acid solution in a boiling water bath, then the protein and fat were precipitated by adding trichloroacetic acid solution. The supernatant was separated on an XDB-C18 column (4.6 mm × 250 mm, 5 μm) using 10% acetonitrile solution as the mobile phase. The analytes were detection with an ultraviolet detector and quantified by the external standard method. The experimental results showed that the correlation coefficient of 5-hydroxymethylfurfural was 0.999 8, with a spiked recovery ranging from 84.6% to 94.3%, a limit of detection (LOD) of 0.005 mg/kg, and a coefficient of variation (CV) of 0.15% to 0.36%. For furfural, the correlation coefficient was 0.999 4, with a spiked recovery rate ranging from 73.7% to 92.0%, a LOD of 0.005 mg/kg, and a CV of 0.95% to 1.54%. This method is characterized by simple operation, low cost, and excellent separation performance, and it is suitable for the quantitative analysis of 5-hydroxymethylfurfural and furfural in liquid milk, providing technical support for the quality control and process optimization of dairy products.

Optimization of the National Standard Method for Salmonella Identification Using Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry

ZHANG Jie, ZHANG Yalun, ZHANG Tao, CHEN Chen, ZHANG Zilun, ZHOU Wei

2026, 49(2):  24-29.  DOI: 10.7506/rykxyjs1671-5187-20251118-080

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The rapid identification of Salmonella, a significant foodborne pathogen, is of significant importance. To establish a new method for identifying Salmonella based on matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), this study optimized culture medium type, incubation time, bacterial lysis methods, and instrumental parameters. The results showed that compared to the national standard method GB/T 33682-2025 General microorganism identification method with matrix-assisted laser desorption/ionization time of flight mass spectrometry, the recovery rate increased from 54.7% to 84.7% after replacing the culture medium with nutrient agar. Increasing the incubation time from 24 to 48 h increased the average identification score by 7.0%, from 2.203 to 2.355. Optimizing lysis methods elevated the average identification score by 19.0%, from 1.898 to 2.259. When the instrumental parameters were adjusted to 50% laser energy and a laser wavelength of 370 nm, the average identification score increased to 2.211. Compared to its original version specified in GB/T 33682-2025, the established MALDI-TOF/TOF MS method exhibited improved accuracy and reliability in Salmonella identification.

Rapid Detection of Exogenous Bovine Insulin in Camel Milk Based on Dispersive Liquid-Liquid Microextraction

YANG Xinyue, CAO Shuangyu, ZHAO Yankun, JIANG Na, Munira·Dilxat, WU Yating, MA Xianlan, CHEN He

2026, 49(2):  30-36.  DOI: 10.7506/rykxyjs1671-5187-20251104-078

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To addresses technical bottlenecks such as the complexity of the camel milk matrix and the interference of endogenous proteins with target detection, this study established an analytical method to detect exogenous bovine insulin in camel milk using dispersive liquid-liquid microextraction (DLLME) coupled with high performance liquid chromatography (HPLC). The extraction conditions and the instrumental parameters were optimized. The results showed that efficient enrichment and accurate quantification of target analytes in complex milk matrices were achieved by HPLC combined with DLLME using 0.01 mol/L HCl as the extractant, volume fraction 60% aqueous acetone as the extraction solvent, and n-hexane as the separation phase. The method exhibited good linearity for bovine insulin over the concentration ranges of 5–500 μg/mL (R2 = 0.999). Recoveries for blank sample of Bactrian camel milk from Dabancheng District, ürümqi ranged from 64.1% to 86.9% at spiked levels of 5, 50 and 500 μg/mL, with relative standard deviations (RSDs) of 4.9%–12.4%. The limit of detection and limit of quantification were 0.5 and 5 μg/mL, respectively. The DLLME-HPLC method is characterized by simple operation, short pretreatment time, and high analytical efficiency, providing technical support for rapid screening of exogenous bovine insulin in camel milk.

Comparative Analysis of Identification Methods for Pediococcus spp. in Food

MING Ruoyang, ZHOU Wei, LIU Yumeng, WANG Hui, LI Yongyan, XIE Mengying, ZHANG Yalun

2026, 49(2):  37-43.  DOI: 10.7506/rykxyjs1671-5187-20251104-073

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In this study, the traditional physiological and biochemical method, a VITEK automatic biochemical analyzer, the analytical profile index (API) biochemical identification system, real-time fluorescence quantitative polymerase chain reaction (real-time PCR) and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) were used comparatively to identify the species of Pediococcus spp. in food. The results showed that the traditional physiological and biochemical method was the most accurate but time-consuming and labor-intensive; the VITEK automatic biochemical analyzer gave unstable results as the database states that Pediococcus acidilactici is negative for amygdalin reaction, whereas some strains actually test positive; the API biochemical identification system yielded accurate results at 24 h of culture, while deviations occurred when the culture period was extended to 48 h; real-time PCR was time-saving, accurate, and suitable for popularization; the MALDI-TOF MS method had the shortest operation time but high equipment requirements, making it difficult to popularize in primary-level institutions. In summary, the traditional physiological and biochemical method, real-time PCR, and MALDI-TOF MS can all serve as standard methods for the identification of Pediococcus spp. in food. The results of this study can provide a technical basis for the formulation of relevant national standards.

Reviews

Synergistic Adjuvant Therapy of Constipation with Probiotics and Prebiotics via Modulation of Gut Microbiota: Mechanisms, Evidence, and Prospects

YUAN Xuefeng, XU Qian, ZHOU Hongmiao, LI Xu, PANG Xiaoyang, LÜ Jiaping, ZHANG Shuwen

2026, 49(2):  44-50.  DOI: 10.7506/rykxyjs1671-5187-20251218-089

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Constipation is a prevalent functional gastrointestinal disorder. Conventional laxative therapies for constipation often entail risks of dependence and adverse effects. With the growing recognition of the crucial role of gut microbiota dysbiosis in its pathogenesis, gut microbiota modulation has emerged as a core strategy in novel therapies. Synbiotics, a combination of probiotics and prebiotics, demonstrates significant therapeutic potential through synergistic mechanisms: prebiotics selectively promote the colonization and proliferation of probiotics, and they synergistically optimize gut microbiota composition, enhance the production of short-chain fatty acids, and subsequently improve intestinal barrier function, regulate immune responses, and stimulate intestinal motility. Clinical evidence indicates that specific synbiotic formulations outperform single-component interventions in improving stool frequency, consistency, and overall symptoms. This advantage stems from the “nutrition-microbiota-metabolism” multiple-pathway synergistic effect. Future research should prioritize the development of personalized synbiotic regimens based on gut microbiota functional prediction, conduct large-scale clinical trials for functional validation, and explore their integration with novel delivery systems and functional food carriers, thereby advancing the development of constipation treatment toward the integration of precision microbiota-based intervention and enhancing its clinical utility and patients’ quality of life.

Recent Advances in Milk Protein Modification: Techniques and Functional Implications

GONG Han, HU Feihan, CHEN Meiling, CHEN Xiao, WANG Jun, MAO Xueying

2026, 49(2):  51-62.  DOI: 10.7506/rykxyjs1671-5187-20251218-088

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Milk protein, a crucial natural raw material in the dairy industry, possesses multiple physiological activities. However, natural milk protein has deficiencies in key functional properties such as thermal stability, solubility, and gel characteristics, which restrict its application in dairy processing. To address this issue, modulation of the molecular structure of milk protein through protein modification technology can not only enhance its basic functionalities but also explore and impart novel functional characteristics to it. This review focuses on the precise regulation of milk protein functional properties and systematically reviews four modification technologies: 1) enzymatic modification such as hydrolysis and cross-linking; 2) physical modification such as non-thermal processing and microencapsulation; 3) chemical modification such as glycosylation, phosphorylation (dephosphorylation), and acylation (deacylation); and 4) combined modification. It discusses these technologies in terms of mechanisms, functional characteristics, and advantages and disadvantages. In light of current research progress, this article also points out that the field still faces several challenges, such as the likelihood of chemical modification causing reagent residues, the high cost of enzyme preparations, the limited effectiveness of single physical modification, and insufficient understanding of the structure-function relationship at the molecular level. Finally, it is proposed that further research should focus on developing targeted green combined modification technologies, investigating the safety and nutritional properties of modified products, and expanding the application of milk protein in high value-added special diets such as infant formula and nutritional products for the elderly, with the aim of providing a theoretical basis and technical support for promoting the high-value utilization of milk protein.

Review of Analytical Methods for Water-Soluble Vitamins in Infant Formula Milk Powder

REN Xiaowei, ZHAI Hongwen, WU Lei, FAN Lixin, DONG Xiaoqian, FAN Sufang

2026, 49(2):  63-70.  DOI: 10.7506/rykxyjs1671-5187-20251104-075

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Water-soluble vitamins, as essential micronutrients for the human body, play a vital role in maintaining normal physiological functions, and their deficiency may lead to metabolic disorders and related health issues. Infant formula is fortified with these vitamins through nutrient fortification technologies to support the healthy growth and development of infants and young children. Due to the matrix complexity of infant formula and the instability of water-soluble vitamins, it is a great challenge to accurately analyze and detect multiple water-soluble vitamins in infant formula. In this paper, we review the latest developments in extraction and separation (protein precipitation, acid hydrolysis, and enzymatic hydrolysis) and detection (microbiological method, liquid chromatography, and liquid chromatography-mass spectrometry) techniques for water-soluble vitamins in infant formula, and we discuss future prospects in this field. Through this review, we aim to provide a reference for relevant researches.

Research Progress on Per- and Polyfluoroalkyl Substances in Milk and Dairy Products

XUE Haiyan, LI Guowei, HAN Chenrui, WANG Cong, YI Meixia

2026, 49(2):  71-80.  DOI: 10.7506/rykxyjs1671-5187-20251222-091

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Per- and polyfluoroalkyl substances (PFASs) have emerged as potential health risks in milk and dairy products due to their chemical inertness and bioaccumulative properties. This paper systematically reviews the detection methods, migration and transformation mechanisms, and pollution control strategies for PFASs in milk and dairy products. Sample preparation techniques including liquid-liquid extraction, solid-phase extraction, QuEChERS (quick, easy, cheap, effective, rugged, and safe), supercritical fluid extraction, and metal-organic framework-based dispersive solid-phase extraction have been widely applied in conjunction with liquid chromatography-tandem mass spectrometry and high-resolution mass spectrometry to achieve precise quantification of PFASs at trace to ultra-trace levels. PFASs migrate through the “environment-feed-cattle-milk” pathway, with significant differences in accumulation and transfer efficiency between short-chain and long-chain PFASs. In dairy cows, PFASs primarily distribute in serum protein-bound forms, and some novel PFASs exhibit uncertainties in biotransformation. During dairy processing, thermal treatment and contact materials may cause redistribution or migration of PFASs. Finally, a comprehensive pollution control strategy combining source control, production process interventions, and active removal technologies provides a scientific basis for reducing exposure to PFASs from dairy products. This review aims to offer theoretical references and practical guidance for dairy product safety regulation, risk assessment, and pollution prevention.