Objective To establish a method for the determination of biotin in formula food for special medical purposes by high performance liquid chromatography-post column derivatization. Methods The biotin in the sample was dissolved in water and extracted by enzymatic hydrolysis with amylase and papain at 60 ℃ for 1 hour in a water bath. Using Zorbax SB-AQ chromatographic column separation and entering the post column reaction device, the biotin was derived from fluorescein isothiocyanate labeled avidin. Derivatives were detected using a fluorescence detector with an excitation wavelength of 495 nm and an emission wavelength of 525 nm. The results were quantified by the external standard method. Results Under the optimized conditions, the biotin showed good (r²>0.999) linear relationships within the concentration range of 5.00‒75.00 ng/mL. The average recoveries were 97.5%‒100.1%, and the relative standard deviations were 0.86%‒2.9%. The limit of detection was 12 μg/kg, and the limit of quantification was 41 μg/kg. The relative standard deviations of the biotin standard solution and the sample solution to be tested within 24 h were 0.68% and 1.08%, respectively. There was no significant difference between the results of this method and GB 5009.256—2016 National food safety standard-Determination of biotin in food. Conclusion This method has simple pretreatment, high recovery, good sensitivity and precision, and can be used for the determination of biotin content in formula food for special medical purposes.

Curdlan, a type of microbial extracellular polysaccharide, is widely utilized as a food additive due to its exceptional gelling, water-holding, thickening, and freeze-thaw stability properties within food systems. In recent years, the research on the regulation of the interaction between curdlan and biomacromolecules has become a research hotspot in the field of food science, aiming at optimizing the texture of food, enhancing the stability of food, and promoting the development of new healthy foods. However, a systematic summary of the interaction between curdlan and biological macromolecules, as well as their regulatory mechanisms is still insufficient at present. As a result, this review offered a comprehensive overview of recent research progress in the interaction between curdlan and biomacromolecules, particularly emphasized the interactions between curdlan and polysaccharides, proteins and other macromolecules in food applications. This review aims to establish a theoretical foundation for the precise design and innovative development of functional foods.

Objective To investigate the type and drug resistance characteristics and virulence gene carrying of some food-borne methicillin-resistant Staphylococcus aureu (MRSA) in Ningxia. Methods MRSA isolates from some food risk monitoring in Ningxia were collected and subjected to drug susceptibility testing, pulsed-field gel electrophoresis (PFGE), and whole-genome sequencing analysis respectively. Results PFGE typing of 9 food-borne MRSA strains was divided into 3 clusters and 8 kinds of types, all of which were more than 85% provenance. ST typing of the whole genome sequencing results was divided into 4 kinds of ST types, 6 strains were ST59, and the other 3 strains were ST3355, ST7 and ST965, respectively. MRSA were all multi-drug resistant, which carrying different resistance genes and virulence genes, resulting in different drug resistance phenotypes. Conclusion Foodborne MRSA isolates have a large number of genes related to antibiotic resistance and pathogenicity, which pose a significant threat to human health. Therefore, it is of great importance to continuously monitor and take effective measures to reduce the contamination level of MRSA in food to ensure food safety.

Objective To establish a quantitative analysis method for determining the content of 5 kinds of lactose derivatives (3'-galactosyllactose, 4'-galactosyllactose, 6'-galactosyllactose, 3'-sialyllactose, 6'-sialyllactose) in milk and dairy products by pre-column derivatization-high performance liquid chromatography. Methods The proteins in milk and dairy products were precipitated. The 5 kinds of lactose derivatives were reacted with 2-aminobenzamide at 55 ℃ for 120 min to label the fluorescent groups. The 5 kinds of lactose derivatives were separated by high performance liquid chromatography with an amide column and quantified by external standard method. Results The 5 kinds of lactose derivatives exhibited good linear relationships within the concentration range of 0.025-5.000 mg/L, with correlation coefficients (r) all exceeding 0.999. The limits of detection and quantification for the 5 kinds of lactose derivatives ranged from 3.5 to 7.5 mg/kg and 12.0 to 25.0 mg/kg, respectively. The recovery rates for the 5 kinds of lactose derivatives were between 90.8% and 103.3%, with relative deviations in detection results ranging from 2.8% to 5.3% (n=3). Conclusion This method demonstrates good precision, recovery rate, and sensitivity, making it suitable for determining the content of 5 kinds of lactose derivatives in milk and dairy products.

Objective To establish a method for the determination of 25 kinds of illegal additives in candy by dispersive solid phase microextraction extraction coupled with ultra performance liquid chromatography-tandem mass spectrometry. Methods The samples were extracted with 50% methanol water, purified by dispersive solid phase microextraction extraction and separated by ACQUITY UPLC TSS T3 column. The samples were then eluted with ammonium formate aqueous solution and ammonium acetonitrile as mobile phase by gradient elution. The samples were determined by ultra performance liquid chromatography-tandem mass spectrometry and quantified by external standard method. Results The results showed that the 25 kinds of illegal additives had good linearity in the range of 2.00 to 50.00 µg/L with a correlation coefficient (r²) greater than 0.99, recoveries were between 65.1% and 99.3%, relative standard deviations were 1.1% to 5.0%, and limit of detection was 0.05 mg/kg and limit of quantification was 0.10 mg/kg. The method was applied to the detection of 105 batches of samples, in which one batch of compressed candy was found to contain xinlisita, and two batches of candy were found to contain dipropylphenidate. Conclusion The method is purified by dispersive solid phase microextraction extraction and detected by ultra performance liquid chromatography-tandem mass spectrometry. The method has good accuracy and high sensitivity, and can meet the detection requirements of 25 kinds of illegal additives in candy.

Objective To explore the effects of dried Dendrobium officinale and fresh Dendrobium officinale on the gut microbiota of normal mice and to provide a reference for its rational development and application. Methods The normal mice were administrated with dried Dendrobium officinale and fresh Dendrobium officinale for 7 days, respectively. The growth of mice was observed, and the mucosa-associated microbiota in the small intestine and colon was detected using the full-length 16S rRNA gene sequencing. Results The results showed that both dried Dendrobium officinale and fresh Dendrobium officinale could control the weight gain of mice, but the weight-control effect of fresh Dendrobium officinale was more significant than that of dried Dendrobium officinale. Both dried Dendrobium officinale and fresh Dendrobium officinale decreased α diversity of mucosa-associated microbiota in the colon. However, fresh Dendrobium officinale increased α diversity of mucosa-associated microbiota in the small intestine, while the effect of dried Dendrobium officinale was the opposite. Moreover, fresh Dendrobium officinale significantly promoted the proliferation of short-chain fatty acid-producing bacteria (Lactobacillus, Faecalibacterium prausnitzii, Butyricicoccus pullicaecorum and Roseburia inulinivorans) in the small intestine and up-regulated metabolic pathways such as lipid metabolism, metabolism of terpenoids and polyketides, carbohydrate metabolism, and xenobiotics biodegradation and metabolism. In colonic mucosa-associated microbiota, dried Dendrobium officinale showed a stronger inhibitory effect on Escherichia coli and Ruminococcus gnavus than fresh Dendrobium officinale. Conclusion The results show that fresh Dendrobium officinale can control body weight and maintain health by promoting the proliferation of beneficial bacteria and up-regulating lipid and carbohydrate metabolism, while dried Dendrobium officinale can inhibit the growth of harmful bacteria, and may help reduce the potential risk of disease.

Objective To optimize the preparation process of Brassica rapa L. polysaccharide oral liquid and test its quality. Methods Graded alcohol precipitation was used to study the yield of crude polysaccharides of Brassica rapa L. at different ethanol concentrations. The optimal formulation of oral solution of Brassica rapa L. polysaccharide was screened by one-way and orthogonal tests, and the quality was tested according to the pharmacopoeia. Results The extraction rates of crude polysaccharide from Brassica rapa L. were 12.8%, 9.2%, 23.2% and 24.8% for the alcohol precipitation group with ethanol concentration of 20%, 40%, 60% and 80%, respectively. The optimal preparation process conditions of oral solution of Brassica rapa L. refined polysaccharide were: 2% addition of Brassica rapa L. crude polysaccharide, 15% addition of honey, 0.6% addition of citric acid and 0.6% addition of sodium citrate. The best preparation process conditions for oral liquid of Brassica rapa L. crude polysaccharide were: 2% addition of Brassica rapa L. crude polysaccharide, 15% addition of honey, 0.6% addition of citric acid, 0.6% addition of sodium citrate. The pH of the oral solution of refined polysaccharide of Brassica rapa L. and the oral solution of crude polysaccharide of Brassica rapa L. were 4-5. The relative density of the oral solution of refined polysaccharide of Brassica rapa L. was 1.106 g/mL. The relative density of the oral solution of crude polysaccharide of Brassica rapa L. was 1.100 g/mL. Conclusion The optimal preparation process conditions for refined polysaccharides from Brassica rapa L. and crude polysaccharides from Brassica rapa L. are the same, but the taste, odor, and appearance of the former are superior to those of crude polysaccharides from Brassica rapa L.. However, the extraction process for refined polysaccharides from Brassica rapa L. is slightly more complex and not suitable for mass production in factories.

Objective To establish a method for simultaneous determination the content of 4 kinds of human milk oligosaccharides [2'--fucosyllactose (2'-FL), 3'-sialic acid (3'-SL), 6'-sialic acid (6'-SL) and lactose-N-neotetraose (LNnT)] in milk powder by liquid chromatography-fluorescence method. Methods The samples were dissolved in water, enzymolized with amyloglucosidase or β-galactosidase, derived with 2-aminobenzamide (2-AB) and 2-methylpyridine borane (2-PB), and separated by amide bonding column, detected by fluorescence detector, and quantitated by internal standard methods. Results The 4 kinds of milk oligosaccharides had a good linear relationship in the concentration range of 10-600 μg/mL, and the correlation coefficients (r²) were more than 0.999. The limits of detection and quantification of 4 kinds of milk oligosaccharides were 0.94-2.31 mg/100 g and 3.12-7.69 mg/100 g, respectively; the recovery rates of 4 kinds of milk oligosaccharides were 97.7%-101.5%, and the relative standard deviations (RSD) (n=7) were 0.53%-3.09%. Conclusion This method does not have high requirements for people, equipments and environment for determining the content of 4 kinds of milk oligosaccharides in milk powder. The pre-treatment operation is simple, and it has good accuracy and precision. It can provide a reference for the quality control method of human milk oligosaccharides in milk powder.

Objective To establish a method for rapid determination of 58 kinds of pesticide residues in animal derived foods by QuEChERS-gas chromatography-tandem mass spectrometry (GC-MS/MS). Methods After dissolving the oil and fat in n-hexane, the sample was subjected to ultrasonic extraction with a saturated acetonitrile solution (containing 1% glacial acetic acid). The extract was purified with anhydrous magnesium sulfate, octadecyl bonded silica gel (C₁₈), and N-propylethylenediamine (PSA), and then nitrogen was blown to near dryness in a water bath. An internal standard was added and dissolved in ethyl acetate. GC-MS/MS was used for determination, and the blank matrix matching standard curve internal standard method was used for quantification. Results The linear relationship between 58 kinds of pesticides was good within the mass concentration range of 0.005-0.500 mg/L, with correlation coefficients (r²) greater than 0.9945. The limits of detection and limits of quantification were 0.001-0.005 mg/kg and 0.002-0.015 mg/kg, respectively. The average recovery rates of pork, chicken, fish, eggs and milk matrices at 3 different spiked levels ranged from 71.8% to 117.4%, with relative standard deviations of 0.7% to 8.7% (n=4). Conclusion This method has high sensitivity and good accuracy, and is suitable for simultaneous determination of 58 kinds of pesticide residues in animal derived foods.

Objective To analyze and evaluate amino acid composition and content of 10 kinds of livestock meats and products in Hunan Province. Methods Kjeltee2300 automatic nitrogen determinator kjeldahl apparatus was used to determine the proteins in 10 kinds of livestock meats and products in Hunan Province. Amino acid composition was measured using membra Pure GmbH A300 automatic amino acid analyzer. The nutritional value of livestock meats and products was evaluated by the amino acid score method. Results There were 17 kinds of amino acids in livestock meats and products except stewed meat with smallpox fungus without proline and sour soup beef without methionine. The content of protein, amino acids and essential amino acids in stir fried pork jerky with red pepper were the highest, which were 19.50, 15.98, 5.98 g/100 g, respectively. The content of lysine in essential amino acids in 10 kinds of livestock meats and products was the highest, Except for leucine, which had the highest essential amino acid content (1.25 g/100 g) in handmade pig blood meatball, all others had the highest lysine content, which were stewed meat with smallpox fungus (0.24 g/100 g), Pingshang omasum (0.38 g/100 g), sour meat (0.49 g/100 g), sour soup beef (0.80 g/100 g), steamed pork balls with pork heart (0.96 g/100 g), large chunks of beef (1.09 g/100 g), stir fried large pieces of meat with wheat sauce (1.16 g/100 g), stir-fried smoked pork (1.36 g/100 g), stir fried pork jerky with red pepper (1.38 g/100 g) respectively, except the content of leucine in essential amino acids in handmade pig blood meatball was the highest (1.25 g/100 g). The content of lysine in 10 kinds of livestock meats and products except Pingshang omasum (50.67 mg/g protein), including steamed pork balls with pork heart (73.85 mg/g protein), large chunks of beef (80.15 mg/g protein), sour meat (64.47 mg/g protein), stewed meat with smallpox fungus (114.29 mg/g protein), stir-fried smoked pork (87.74 mg/g protein), stir fried large pieces of meat with wheat sauce (70.73 mg/g protein), sour soup beef (77.67 mg/g protein), handmade pig blood meatball (63.19 mg/g protein), stir fried pork jerky with red pepper (70.77 mg/g protein), were higher than the (World Health Organization) WHO/(Food and Agriculture Organization) FAO model value (55 mg/g protein) and ovalbumin pattern value (55 mg/g protein). The limited amino acid in 10 kinds of livestock meats and products was isoleucine or valine. Conclusion Excellent lysine content and high nutritional value in livestock meats and products; it is possible to combine the consumption of foods rich in isoleucine or valine to construct a reasonable diet and enhance their nutritional value.