Objective To compare the differences in spectral characteristics and monocyte immune effects for bacterial endotoxin from different sources. Methods Ultraviolet absorption spectrum and three-dimensional fluorescence spectrum were used to identify excipients (polyethylene glycol 8000 and α-lactose) and biological impurities (protein and nucleic acid) in 5 kinds of control standard endotoxin. Biological contamination was further confirmed by the detection of Toll-like receptors (TLRs) in HL-60 cells. The monocyte activation test was used to compare the release of the inflammatory cytokines interleukin 6 (IL-6), interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) caused by 5 kinds of endotoxins on HL-60 cells. Results As for control standard endotoxin, absorption peaks related to excipients were observed in ultraviolet absorption spectrum, while fluorescence peaks related to excipients and proteins were shown in three-dimensional fluorescence spectrum. The expression levels of TLRs of HL-60 cells indicated that protein contamination was more significant than nucleic acid contamination. All endotoxins induced improvement in cellular IL-6 and IL-1β gene relative expression levels and their protein mass concentrations in HL-60 cells. However, the TNF-α gene relative expression levels and its protein concentrations were not elevated. Endotoxins from the same or different bacterial strains had significant differences in their ability to induce inflammation under the same endotoxin activities. Conclusion Excipients and protein contamination of endotoxins are identified by spectral detection, while proteins and nucleic acids in biological impurity are confirmed by the TLRs assay of HL-60 cells. Molecular structure of endotoxins, as well as protein contamination influence the ability of endotoxins to induce the release of the inflammatory cytokines.

Objective To study the effects of ultraviolet pre-sterilization on the quality of fresh pork. Methods Different packaging conditions (bare packaging and fresh-keeping bag packaging), irradiation distance (6, 9 and 12 cm) and irradiation time [bare packaging (3, 5, 10 s), fresh-keeping bag packaging (6, 10, 14 s)] were set in this study. The feasibility of ultraviolet treatment to reduce the number of pork microorganisms and prolong the shelf life of pork was explored by measuring the total number of colonies, sensory evaluation, color difference, total volatile basic nitrogen (TVB-N) and thiobarbituric acid reactive substances (TBARS). Results The results showed that the best ultraviolet irradiation conditions for naked packaged fresh pork were 9 cm-10 s, and the best ultraviolet irradiation conditions for fresh-keeping bag packaged pork were 6 cm-14 s, which could reduce the initial microbial number of fresh pork by 0.44 logCFU/g and 0.61 logCFU/g, respectively, but had no significant effect on fat oxidation, sensory evaluation and color. Conclusion The ultraviolet pre-sterilization treatment can reduce the initial number of microorganisms in pork, slow down the increase of TVB-N value and lipid oxidation, and has no significant effect on the sensory quality and color of fresh meat. The shelf life of pork is prolonged by 3-4 d, which has potential application value in the field of pork preservation.

Objective To investigate the effects of shading and drought on the quality of black tea and white tea in summer and autumn. Methods Light fermented white tea and heavy fermented black tea were processed through multiple experimental settings of shade, drought, and a combination of shade and drought. The 4 groups of black tea and white tea samples were evaluated for sensory quality. Additionally, high performance liquid chromatography (HPLC) and headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) technologies were employed to conduct a comparative analysis of quality components and taste components. Results Shading combined with drought treatment increased the levels of water extracts, free amino acids, umami amino acids such as theanine, sweet amino acids like threonine, alcohols, thereby significantly enhanced the fresh taste of the tea (P<0.05). Concurrently, in black tea, the concentrations of bitter amino acids such as valine, tea polyphenols, catechins were reduced, leading to a marked decrease in the bitterness and astringency of summer and autumn tea (P<0.05). Aroma testing revealed a total of 98 substances in black tea, with alcohols being the most prevalent. The concentration in the shade plus drought group was significantly higher than the drought group (P<0.05). In white tea, 85 substances were identified, with alcohols comprising the largest proportion. Conclusion The findings of this study offer new insights for the production of black and white tea under extreme summer and autumn weather conditions. This approach not only effectively mitigates the bitterness of summer and autumn tea but also enhances the utilization rate of fresh leaves, providing crucial guidance for tea garden production management.

Objective To explore the types and contents of amino acids in Asparagus from different sources. Methods Post-column ninhydrin-derived photometry was established to determine the species and contents of amino acids in Guangxi, Neijiang and southwest winter, and performed data analysis using stoichiometry. Results The average amino acid content in Neijiang was 3.06%, 3.53% in Guangxi, and 5.73% in southwest China. The amino acid composition and content in Neijiang and Guangxi were similar, and the content was uniform among different batches, the amino acid content in southwest and southwest was quite different from the first two sources, and the different batches were quite different. Conclusion This research provides scientific reference for quality evaluation of Asparagus and the study of its authenticity.

Objective To synthesize a Au-Pt bimetallic nanozymes (Au-PtNFs) with oxidase and peroxidase dual-enzyme activity, and apply them in detection of organophosphorus pesticide. Methods The 3 kinds of Au-PtNFs were prepared through seed-mediated method by adjusting the amount of chloroplatinic acid, and their enzyme activities were determined using 3,3’,5,5’-tetramethylbenzidine (TMB) as the substrate. The nanozyme exhibiting the highest enzyme activity was selected and combined with the catalytic effect of acetylcholinesterase to establish a detection method for organophosphorus pesticide. Results The 3 kinds of prepared nanozymes all had flower-like structures, and the particle size enhanced with the increasement of chloroplatinic acid concentration. Steady-state dynamic experiments showed that all bimetallic nanozymes had dual-enzyme activity, and the best enzyme activity was obtained when the concentration of chloroplatinic acid was 5 mmol/L. Absorption at 620 nm exhibited a good linear correlation with the logarithm of chlorpyrifos concentration in the range of 40-90 nmol/L, and the limit of detection was 1.00 nmol/L. The method demonstrated excellent specificity and anti-interference ability, and achieved great recovery rate in real samples. Color value analysis software was used for the detection of chlorpyrifos based on smartphone. The linear range was 30-100 nmol/L and the limit of detection was 1.06 nmol/L. Conclusion The prepared Au-PtNFs exhibiting dual-enzyme activity are effectively utilized for detection of organophosphorus pesticides, which offers a novel perspective for visual detection of organophosphorus pesticides in fruits and vegetables.

Objective To explore the effects of nine steaming and nine processing methods on the characteristics, microstructure, and effective components of Polygonatum sibiricum, and provide relevant basis for the processing technology of Polygonatum sibiricum. Methods Jiuhuangjing was prepared using the nine steaming and nine preparation method, and its characteristics, microstructure, and active ingredients were evaluated as quality control indicators for evaluation. Results After six steaming and six processing, the appearance of Polygonatum sibiricum basically meets the requirements of the Chinese pharmacopoeia. The surface of Polygonatum sibiricum after nine steaming and nine processing was black, oily, and smooth, with a uniform and glossy color. The interior was black with red inside and black inside, with a honeycomb like structure. The structure of calcium oxalate was broken, the content of polysaccharides and the water-soluble components were reduced, and the alcohol soluble components were increased. This suggested that after nine steaming and nine processing, the irritants of Polygonatum sibiricum gradually decrease, the polysaccharides undergo hydrolysis, and gradually decompose into monosaccharides, and the taste changes from sour to sweet without a tingling sensation. Conclusion This experiment establishes a scoring standard for the characteristics of nine steamed and nine processed Polygonatum sibiricum, in order to provide a basis for the quality identification and construction of quality standards for nine steamed and nine processed Polygonatum sibiricum.

Objective To construct a method for rapid detection of chromium (VI) in drinking water on a paper-based microfluidic chip. Methods The paper chips were manufactured by directly drawing on filter paper with a modified gel pen filled with alkylketene dimmer solution and then dried. The chromium (VI) was detected on the paper chips. Parameters influencing the chromium (VI) determination were investigated, including concentration of sulfuric acid solution and diphenyl carbamide solution, reaction time, and temperature. Results In this study, the linear range of chromium detection was 0~0.20 mg/L, the detection limit was 0.0036 mg/L, and the recovery rate was 97.7%~109.0%. It had wide linear range, high sensitivity and good repeatability. Conclusion The method has the advantages of simple operation and the accurate detection result, does not require expensive and complex large instruments, and has adaptability to simultaneous detection of multiple samples and on-site real-time detection.

Objective To establish a highly sensitive analytical method for the determination of advantame in alcoholic beverages by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Methods The wine samples were diluted 10 times with ultrapure water, filtered through a membrane, and then injected. A Kinetex^® Biphenyl 100 Å chromatographic column (100 mm×3.0 mm, 2.6 μm) was used, with water and methanol as the mobile phase for gradient elution and separation. An electrospray ionization source (ESI) was adopted for detection in the positive ion scan multiple reaction monitoring (+MRM) mode, and external standard method was used for quantification. Results Advantame exhibited an excellent linear relationship within the mass concentration range of 0.03 to 40.00 μg/L, with a correlation coefficient of 0.9999. The limit of detection was 0.10 μg/kg, the limit of quantification was 0.30 μg/kg. The average recoveries at the 4 different spiked levels of low, medium-low, medium-high and high were 80.8% to 109.8%, and the relative standard deviation was 2.7% to 12.5% (n=6). Conclusion This method has high detection sensitivity, is simple to operate, accurate and reliable, and can be used for the trace analysis and risk assessment of advantame in alcoholic foods, providing strong technical support for scientific supervision of the alcoholic beverage market.