Structure of yuba films at the air/liquid interface as effected by the interfacial adsorption behavior of protein aggregates.

The effects of adsorption behavior and assembly mechanism of proteins and lipids at the interface on the formation of yuba films were investigated. The thickness of yuba films increased rapidly from nano to micro scale within minutes according to the scanning electron microscopy (SEM) images. The confocal laser scanning microscope (CLSM), SEM images, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the formation of protein aggregates (40-100 nm) was an essential requirement for the development of yuba. Meanwhile, a relatively loose spatial structure was formed by protein aggregates under the influence of water vapor. This structure served as the foundation for incorporating lipids. Interfacial adsorption kinetics indicated that increasing the concentration (from 3 to 9 mg/mL) of protein aggregates enhanced the rearrangement rate. This finding demonstrated that the variations of interfacial protein aggregate concentration were a crucial factor leading to the non-linear growth of film thickness.

Distinct changes of taste quality and metabolite profile in different tomato varieties revealed by LC-MS metabolomics.

Breeding of tomato varieties based on phenotypic traits can potentially lead to a decline in taste and nutritional values, thereby impacting consumer acceptance. However, taste is an intrinsic characteristic of tomatoes. Its decoding requires the identification of crucial compounds and the associated metabolic pathways implicated in taste development and formation. In this study, the taste parameter differences of four tomato varieties were distinguished using an electronic tongue. The content of organic acids and free amino acids, which were closely associated with taste variations, was quantitatively analyzed. Several important taste metabolites and metabolic pathways were identified based on LC-MS metabolomics and enrichment analysis. Through correlation analysis, it was determined that there existed significant associations between the taste, compounds, and metabolites of tomato varieties with different phenotypes. This study could provide references and theoretical basis for tomato breeding, as well as the control and evaluation of taste and quality of tomato varieties.

Insight into the relationship between metabolite dynamic changes and microorganisms of sea urchin (S. intermedius) gonads during storage.

Sea urchin gonads have high nutritional value and degenerate rapidly during storage. Previous assessment of the freshness of sea urchin gonads was based on experience without valid biochemical indicators. Thus, the current study is to find biochemical indicators representing the freshness of sea urchin gonads. Results showed that the dominant genera of sea urchin gonads were changed from Psychromonas, Ralstonia, and Roseimarinus to Aliivibrio, Psychrilyobacter, and Photobacterium. The differential metabolites of sea urchin gonads were mainly produced through amino acids metabolism. Among them, GC-TOF-MS based differential metabolites had the greatest enrichment in the valine, leucine and isoleucine biosynthesis pathway, while LC-MS based differential metabolites had the greatest enrichment in the alanine, aspartate and glutamate metabolism pathway. The growth of dominant genus (Aliivibrio) had a great influence on the production of differential metabolites. These results will provide valuable information for accurately judging the freshness and shelf life of sea urchin gonads.

Effects of sous vide cooking combined with ultrasound pretreatment on physicochemical properties and microbial communities of Russian sturgeon meat (Acipenser gueldenstaedti).

BACKGROUND: The production of Russian sturgeon is expanding rapidly in China but it is necessary to adopt measures to extend the shelf life of sturgeon meat. Previous studies found that sous vide cooking (SVC) at 60 °C increased the protein and lipid oxidation. The addition of antioxidant substances reduced the acceptance of the product. The effect of combination SVC and ultrasound pretreatment was therefore investigated. RESULTS: Results showed that SVC at 50 °C combined with ultrasound effectively restrained the growth of total viable counts (TVC) in samples. Meanwhile, the main dominant genera changed from Pseudomonas to Carnobacterium and the number of microbial species decreased. The odor profile of Russian sturgeon meat was more stable and the lipoxygenase (LOX) activity decreased more rapidly after treating with SVC and ultrasound. Importantly, more stable protein aggregates were formed in samples treated by SVC 50 °C together with ultrasound pretreatment, so the protein and lipid oxidation were slowed during storage. Higher springiness values were obtained and the color of sturgeon meat was lighter under these conditions. CONCLUSION: The combination of SVC 50 °C and ultrasound pretreatment effectively inhibited the microbial growth of Russian sturgeon meat at lower oxidation levels. These findings theoretically support the preservation and development of sturgeon meat, and the application of SVC technology. © 2022 Society of Chemical Industry.

Ni-Catalyzed Enantioselective Benzylation of Secondary Phosphine Oxide.

A nickel-catalyzed benzylic substitution of secondary phosphine oxide was described, affording the dialkylated P-stereogenic tertiary phosphine oxides with high to excellent enantioselectivities. The reaction was performed under mild conditions with commercially available benzyl chlorides and bench stable secondary phosphine oxides, exhibiting broad functional group tolerance. It represented a practical example for the preparation of P-stereogenic phosphine compounds.

Changes in food quality and microbial composition of Russian sturgeon (Acipenser gueldenstaedti) fillets treated with low temperature vacuum heating method during storage at 4 °C.

Russian sturgeon is a high-quality cultured fish and traditional heating methods may lead to deterioration of its food quality. This study aimed to evaluate the food quality and microbial composition of sturgeon fillets by low temperature vacuum heating (LTVH) and storage at 4 °C. The treatments varied in temperature (50, 60, and 70 °C) and duration (15 and 30 min); samples treated by traditional heating (100 °C, 15 min) methods were included as controls. We found that LTVH could reduce the values of lightness (L*), yellowness (b*), and pH and increase the values of redness (a*), chewiness, and hardness, to promote food quality. The biogenic amine content declined with the increase in heating temperature and time, the histamine of most concern was low at the end of storage, the values of LTVH70-30 and TC was 33.12 ± 1.25 and 30.39 ± 0.86 mg/kg. The total viable count (TVC) and biogenic amines showed the same trend, and the finial TVC values of LTVH60-30, LTVH70-15, LTVH70-30 and TC were 6.72 ± 0.17, 6.33 ± 0.18, 6.18 ± 0.08 and 5.93 ± 0.16 log CFU/g, which did not exceed the limit value (7 log CFU/g), indicating that the biosafety risk was reduced. According to the high-throughput sequencing results, the microbial composition of LTVH samples showed a lesser abundance pseudomonads than that found in the control. Thus, LTVH technology could be used as an alternative to traditional heating treatment.

Effect of low-temperature vacuum heating on physicochemical properties of sturgeon (Acipenser gueldenstaedti) fillets.

BACKGROUND: Sturgeon is popular for its nutritious value and its taste. However, sturgeon fillets are traditionally heated in 100 °C boiling water, resulting in unfavorable taste and with a negative effect on the quality. This study considered the effect of combinations of vacuum and low-temperature treatments (LTVH groups) on sturgeon fillets compared with the traditional heat treatment (TC groups). RESULTS: The results show that the LTVH groups had lower cooking-loss rates. All LTVH fillets were changed to a white color, and appeared 'done', as did the TC fillets. The LTVH and TC methods gave rise to significant differences in texture: the springiness of the LTVH groups decreased with heating time, and decreased rapidly in the TC groups (P < 0.05); hardness and chewiness increased with time and temperature in the LTVH groups, but decreased in the TC groups. More compact and denser gaps were observed in LTVH70 groups and TC groups. Less protein and lipid oxidation was evident in LTVH groups, including more myofibril protein solubility; there was less protein aggregation, fewer thiobarbituric acid reactive substance, and Schiff base. CONCLUSION: Vacuum and low-temperature treated sturgeon fillets can be served as a good alternative. This treatment caused slight tissue damage and less proteolysis and lipid oxidation, which is beneficial for the quality of aquatic products.

Alkyl Ferulate Esters as Multifunctional Food Additives: Antibacterial Activity and Mode of Action against Escherichia coli in Vitro.

This work aims to prepare ferulic acid alkyl esters (FAEs) through the lipase-catalyzed reaction between methyl ferulate and various fatty alcohols in deep eutectic solvents and ascertain their antibacterial activities and mechanisms. Screens of antibacterial effects of FAEs against Escherichia coli ATCC 25922 ( E. coli) and Listeria monocytogenes ATCC 19115 ( L. monocytogenes) revealed that hexyl ferulate (FAC6) exerted excellent bacteriostatic and bactericidal effects on E. coli and L. monocytogenes (minimum inhibitory concentration (MIC): 1.6 and 0.1 mM, minimum bactericidal concentration (MBC): 25.6 and 0.2 mM, respectively). The antibacterial mechanism of FAC6 against E. coli was systematically studied to facilitate its practical use as a food additive with multifunctionalities. The growth and time-kill curves implied the partial cell lysis and inhibition of the growth of E. coli caused by FAC6. The result related to propidium iodide uptake and cell constituents' leakage (K+, proteins, nucleotides, and ß-galactosidase) implied that bacterial cytomembranes were substantially compromised by FAC6. Variations on morphology and cardiolipin microdomains and membrane hyperpolarization of cells visually verified that FAC6 induced cell elongation and destructed the cell membrane with cell wall perforation. SDS-PAGE analysis and alterations of fluorescence spectra of bacterial membrane proteins manifested that FAC6 caused significant changes in constitutions and conformation of membrane proteins. Furthermore, it also could bind to minor grooves of E. coli DNA to form complexes. Meanwhile, FAC6 exhibited antibiofilm formation activity. These findings indicated that that FAC6 has promising potential to be developed as a multifunctional food additive.

Evaluation of Outpatient Antibiotic Use in Beijing General Hospitals in 2015.

BACKGROUND: Medical misuse of antibiotics is associated with the acquisition and spread of antibiotic resistance, resulting in a lack of effective drugs and increased health-care cost. Nevertheless, inappropriate antibiotic use in China remains common and the situation requires urgent improvement. Here, we analyzed the prescriptions of antibiotics and evaluated the rationality of antibiotic use among outpatients in Beijing general hospitals during 2015. METHODS: We collected basic medical insurance claim data from January 1, 2015 to December 31, 2015 in 507 general hospitals of Beijing. A descriptive analysis of outpatient antibiotic prescribing was performed. The Anatomical Therapeutic Chemical Classification/defined daily doses system was used to evaluate the rationality of antibiotic use. RESULTS: Over the study, an estimated 721,930, 613,520, and 822,480 antibiotics were dispensed in primary, secondary, and tertiary general hospitals corresponding to 5.09%, 5.06%, and 2.53% of all prescriptions, respectively. Antibiotic combinations represented 2.95%, 7.74%, and 10.18% of the total antibiotic prescriptions, respectively. Expenditure for the top twenty antibiotics in primary, secondary, and tertiary general hospitals was RMB 42.92, 65.89, and 83.26 million Yuan, respectively. Cephalosporins were the most frequently prescribed class of antibiotic in clinical practice. The antibiotics used inappropriately included azithromycin enteric-coated capsules, compound cefaclor tablets and nifuratel nysfungin vaginal soft capsules in primary hospitals, amoxicillin and clavulanate potassium dispersible tablets (7:1) and cefonicid sodium for injection in secondary hospitals, cefminox sodium for injection and amoxicillin sodium and sulbactam sodium for injection in tertiary hospitals. CONCLUSIONS: Antibiotic use in Beijing general hospitals is generally low; however, inappropriate antibiotic use still exists. Inappropriately used antibiotics should be subject to rigorous control and management, and public policy initiatives are required to promote the judicious use of antibiotics.