摘要：
<jats:title>Abstract</jats:title><jats:p>The unique sequence of the α‐chain is the structural cornerstone of the collagen triple helix that dictates its conformation and molecular behavior. In this study, collagen‐like peptides of varying sequence characteristics were designed to elucidate the role of Ser (polar residues), Ala (non‐polar residues), and Arg/Glu (ionizable residues) in the formation, kinetics, and stability of the triple helix, and its self‐assembly behavior. We found that the introduction of other common amino acids in (Gly‐Hyp‐Pro)<jats:sub>n</jats:sub> results in varying degrees of decrease in the rate of formation and stability of the triple helix conformation and the self‐assembly into higher order structures. The introduction of Ser showed a maximal detrimental effect on these processes, followed by the Arg/Glu and Ala. Collagen‐like peptides with Ser could not form thermodynamically stable triple helix conformations and lost their ability to further self‐assemble. Arg/Glu promoted the self‐assembly of collagen‐like peptides, and electrostatic interactions and hydrogen bonding were key to the self‐assembly of periodic ordered structures similar to natural collagen. The hydrophobic interactions of Ala also accelerated self‐assembly to some extent, however, due to the lack of directionality of hydrophobic interactions, the formation of the long‐range ordered structure was affected negatively.</jats:p>
摘要：
Ultra-high pressure technology has attracted a great deal of attention in recent years, and has been widely used in food science, medicine, and other fields. This study aimed to determine the effect of ultra-high pressure on the structure and properties of collagen. Native collagen extracted from bullfrog skin was processed under different ultra-high pressure treatment conditions (300, 400, and 500 MPa). Then systematic analysis of the molecular structures and properties of the samples after ultra-high pressure treatment were performed. It was found that the conformation of collagen molecules could be adjusted by ultra-high pressure treatment, and this regulation was closely related to the level of treatment pressure. A possible mechanism of the impact of ultra-high pressure on the collagen molecular structures was speculated according to the experimental results. At low pressure levels (300-400 MPa), the pressure perpendicular to collagen axis dominates and leads to a tightening of the triple helix structure of collagen, while the pressure parallel to collagen axis is dominant and the triple helix tends to dissociate like a zipper at high pressure levels (> 400 MPa). These structural changes would simultaneously result in various changes to thermal stability, self-assembly properties, and antigenicity of collagen. (C) 2018 Elsevier B.V. All rights reserved.
通讯机构：
[Cai, J; He, JR] W;[Xiong, Xin-Gao] H;Wuhan Polytech Univ, Sch Food Sci & Engn, Wuhan 430023, Hubei, Peoples R China.;Huazhong Univ Sci & Technol, Dept Otorhinolaryngol Head & Neck Surgery, Union Hosp, Tongji Med Coll, Wuhan 430022, Hubei, Peoples R China.;Wuhan Polytech Univ, Key Lab Deep Proc Major Grain & Oil, Minist Educ, Wuhan, Hubei, Peoples R China.
关键词：
Starch;Porous starch;Microencapsulation
摘要：
In this study, starch with porous structures derived from purple sweet potato was prepared and used as a food grade polymer for the microencapsulation of olive oil. The optimal reaction conditions for preparing porous starch were determined to improve its adsorption capacity as effective microcapsule-wall materials. Olive oil was then impregnated in microspheres, and loading ratio was optimized by investigating the restrictive factors, including the mass ratio of olive oil to porous starch, as well as the embedding temperature and time. The presence of olive oil in the starch matrix was confirmed by SEM, FTIR, and TGA. Results demonstrated that the porous starch-based microencapsulation exhibit a stable olive oil loading ratio and a significant improvement in oxidative stability compared with free olive oil. The newly-proposed process used in this work was easy to scale up for developing a new and attractive method for oil protection in the food industry. (C) 2018 Elsevier B.V. All rights reserved.
摘要：
A Hybrid collagen fibril (HCF) assembled from xenogeneic collagens is a special kind of collagen fibrils in vivo and plays an important role in living systems. Inspired by nature, can a HCF form in vitro? Herein, we fabricated a new HCF by neutralizing a mixture of type I bullfrog (Rana catesbeiana Shaw) skin collagen and porcine (Sus scrofa domesticus) skin collagen with a phosphate buffer, and investigated its physicochemical properties. Self-assembly kinetics and fluorescence-quenching experiments showed that a significant intermolecular interaction and co-assembly behavior occurred between bullfrog skin collagen and porcine skin collagen, thus confirming that xenogeneic collagens can self-assemble to form HCF. Differential scanning calorimetry revealed that the thermal stability of HCF was completely different from that of the syngeneic bullfrog skin and porcine skin collagen fibrils. This finding indicated that a new kind of collagen fibril was fabricated successfully. Scanning electron microscopy and transmission electron microscopy tests showed that the diameters and D-periodicity lengths of HCF were smaller than those of the syngeneic collagen fibrils, suggesting that the morphological features of HCF were distinguished from those of the syngeneic fibril samples. Moreover, viscoelasticity of a collagen gel also changed after the self-assembly of xenogeneic collagens. Meanwhile, the obtained hybrid gel still exhibited good biocompatibility and cell proliferation properties. Finding from this work provides a new idea for the improvement or regulation of collagen-based products performance.
作者机构：
[刘闪; 刘良忠; 陈阳明; 杨永生; 汪海波] College of Food Science and Engineering, Wuhan Polytechnic University, Wuhan;430023, China;Aquatic Products Engineering and Technology Research Center of Wuhan City, Wuhan;[刘闪; 刘良忠; 陈阳明; 杨永生; 汪海波] 430023, China <&wdkj&> Aquatic Products Engineering and Technology Research Center of Wuhan City, Wuhan;[刘闪; 刘良忠; 陈阳明; 杨永生; 汪海波] 430023, China
通讯机构：
College of Food Science and Engineering, Wuhan Polytechnic University, Wuhan, China
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：
Controlling the fibril-formation process of collagen in vitro to fabricate novel biomaterials is a new area in the field of collagen research. This study aimed to determine the effect of ultrasonication on collagen fibril formation and the properties of the resulting collagen gels. Native collagen, extracted from the skin of grass carp, self-assembled under ultrasonic conditions (at different ultrasonic power and duration). The self-assembly kinetics, fibrillar morphology, and physical and cell growth-promoting properties of the collagen gels were analyzed and compared. The results showed that the self-assembly rate of collagen was increased by ultrasonication at the nucleation stage. The resulting fibrils exhibited smaller diameters and D-periodicity lengths than that of the untreated collagen samples (p < 0.05). The viscoelasticity and textural properties of collagen gels also changed after ultrasonication at the nucleation stage. Texture profile analysis and cell proliferation assays showed that ultrasonication produced softer collagen gel colloids, which were more suitable for cell proliferation than the untreated collagen gels.
摘要：
In this study, fibrillogenesis and thermal dissociation of pepsin-soluble collagen (PSC), extracted from snakehead (Channa argus) skin, were monitored by fluorescence method based on thioflavin T (Th-T), where the accuracy and sensitivity were evaluated and compared with those of turbidity assay. The fluorescence method revealed the fibrillogenesis dynamics of collagen with better sensitivity, especially at nucleation and plateau stages. The melting temperature (T-m) of PSC was estimated to be 47 degrees C by circular dichroism spectroscopy; below this temperature, the triple-helical structure should be intact. After that, the dynamic process of collagen dissociation was explored by the fluorescence method, and verified by morphological analysis of the fibrils and the proportion of retained fibrils. The thermal dissociation critical temperature (TDCT) of PSC fibrils was confirmed to be 39 degrees C. The fluorescence intensity of fibril-incorporated Th-T gradually decreases in the dissociation process, and the decrease rate can be accelerated by increasing temperature. Finally, the thermal stability of triple-helical structures of free-, assembled- and dissociated-PSC was compared. Thus, we demonstrated the formation and thermal dissociation of collagen fibrils in vitro by a fluorescence method based on Th-T. This approach may advance the understanding of fibril formation and inverse dissociation of fish-sourced collagen in vitro. (C) 2016 Elsevier B.V. All rights reserved.
作者机构：
[邓明霞; 汪海波; 杨玲; 张含俊] Department of Chemical and Environmental Engineering, Wuhan Polytechnic University, Wuhan, 430023, China;[刘良忠] Collage of Food Science and Technology, Wuhan Polytechnic University, Wuhan, 430023, China;[黄爱妮] Food Engineering College, Wuchang Institute of Technology, Wuhan, 430065, China
通讯机构：
Department of Chemical and Environmental Engineering, Wuhan Polytechnic University, Wuhan, China
作者机构：
[江颖] Collage of Food Science and Technology, Wuhan Polytechnic University, Wuhan, 430023, China;[汪海波; 张含俊; 邓明霞] Department of Chemical and Environmental Engineering, Wuhan Polytechnic University, Wuhan, 430023, China;[汪海波] Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
通讯机构：
[Wang, H.] D;Department of Chemical and Environmental Engineering, China
