摘要：
Purpose: To improve the solubility and stability of arbutin and to expand its application by preparing its inclusion complex with hydroxypropyl-β- cyclodextrin (HP-β-CD).Methods: An inclusion complex made of arbutin and hydroxypropyl-β-cyclodextrin (HP-β-CD) was prepared by freeze-drying method. Various analytical techniques, including ultraviolet-visible spectroscopy (UV), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), x-ray diffractometry (XRD) and thermo-gravimetric/differential scanning calorimetry (TG/DSC), were used to characterize the inclusion complex.Results: UV spectra indicated that no new unsaturated bond was formed in the inclusion complex. Infrared analysis showed that the smaller peaks in the proximity of 1450 - 1600 cm-1 were characteristic of the aromatic nucleus, indicating that the phenyl ring of arbutin was involved in the formation of the inclusion complex. Scanning electron micrographs of the inclusion complex showed that the original morphology of both components disappeared, and some tiny aggregates of amorphous areas of irregular size were present, revealing that the arbutin was dispersed in HP-β-CD. The powder XRD pattern of the inclusion complex was more similar to that of amorphous HP-β-CD and did not exhibit the characteristic peaks of arbutin which suggest that arbutin in HP-β-CD matrix was molecularly dispersed, and existed in an amorphous state. The TG curve of the inclusion complex was a one-step process, partly proving the formation of the complex. Complex formation with HP-β-CD remarkably improved the physical and chemical stabilities of arbutin.Conclusion: Inclusion complex of arbutin with HP-β-CD improves the heat stability of arbutin remarkably. This has a potential for expanding the application of arbutin to pharmaceuticals and food.Keywords: Arbutin, Hydroxypropyl-β-cyclodextrin, Inclusion complex, Physicochemical properties, Stability, Solubility
摘要：
Much work has been done to understand the self-assembly properties of collagens from mammals. However, there is little information about fish-sourced collagens that are advantageous in certain applications. In this study, the self-assembly dynamics of tropocollagen (with telopeptides) and atelocollagen (without telopeptides) extracted from snakehead (Channa argus) skins was studied with turbidity, dynamic rheology, scanning electron microscopy (SEM), and quantitative percentage of self-assembly. Turbidity results indicate that the self-assembly of fish-sourced collagens followed the nucleation-growth two-step model, while rheological results unveiled two growth stages in the development of collagen gels. Based on SEM, telopeptides promoted the formation of thicker fibrils and increased the density of network that provided the structural basis of increased turbidity and strengthened storage and loss moduli. The SEM data were supported by the increased percentage of self-assembled collagens by telopeptides. Findings from this work may facilitate the understanding of structures and functions of products containing fish-sourced collagens and their application.
摘要：
Vibrio parahaemolyticus usually occurs in coastal areas and is generally recognized as a marine bacterium. It has become the leading cause of gastroenteritis worldwide. In the present study, 96 V. parahaemolyticus isolates were obtained from freshwater crayfish (Procambarus clarkii) and classified by multilocus sequence typing. Fifty-three sequence types (STs) were identified among the 96 isolates analyzed, 38 of which were novel STs. These isolates fell into six groups and 42 singletons, suggesting a high level of genetic diversity. Screening for 9 virulence and virulence-related genes in the isolates revealed that 40 isolates contained more than two genes with possible roles in pathogenicity. The virulence of the representative isolates VP66 (trh(+), ureC(+), T3SS1(+), T3SS2 beta(+), T6SS2(+)) and VP80 (T3SS1(+), T6SS1(+), T6SS2(+)) were further assessed in zebrafish and mouse infection model in vivo, and the tested isolates were shown to be lethal to both zebrafish and mice. These results suggest that crayfish may serve as a carrier of V. parahaemolyticus in freshwater, and that some isolates may have the potential to cause foodborne disease in humans. (C) 2016 Elsevier B.V. All rights reserved.
摘要：
Konjac glucomannan (KGM) is a water-soluble polysaccharide with extraordinary ability to absorb water and increase viscosity and therefore a potential strategy to increase satiety and control food intake. However, it is difficult to incorporate KGM in aqueous foods without increasing viscosity significantly. In the present work, the objective was encapsulate KGM powder as the core of oil droplets in solid/oil/water emulsions to prevent the hydration of KGM and viscosity increase. Blending soy lecithin with soy oil enabled better mixing of KGM powder and oil and enabled the encapsulation of KGM powder at a sufficiently high concentration of whey protein isolate (WPI), as indicated by low viscosities. Preheating WPI reduced the amount of proteins required to encapsulate KGM. The gradual digestion of oil droplets by pepsin at simulated gastric conditions enabled the gradual hydration of encapsulated KGM powder to increase viscosity. These results suggest the feasibility of S/O/W emulsions to deliver KGM in aqueous foods without generating a high viscosity but enabling gradual increase of viscosity during gastric digestion to potentially impact satiety and food intake.
