为探究真空低温蒸煮(sous-vide,SV)罗非鱼片在冻藏过程中的品质变化,将常压高温蒸煮处理(TH)罗非鱼片作为对照组,以水分含量、质构、菌落总数、挥发性盐基氮(total volatile base nitrogen,TVB-N)值、pH、肌原纤维蛋白二级结构和三级结...为探究真空低温蒸煮(sous-vide,SV)罗非鱼片在冻藏过程中的品质变化,将常压高温蒸煮处理(TH)罗非鱼片作为对照组,以水分含量、质构、菌落总数、挥发性盐基氮(total volatile base nitrogen,TVB-N)值、pH、肌原纤维蛋白二级结构和三级结构等为指标,分析在-18℃冻藏120 d对真空低温蒸煮罗非鱼片品质特性和肌原纤维蛋白结构的影响。结果表明,冻藏120 d后,SV组罗非鱼片的水分含量损失2.26%,低于TH组的3.61%;与TH组相比,SV组的罗非鱼片在冻藏过程中一直维持着优于TH组的硬度、弹性和咀嚼性;TH组的菌落总数、TVB-N、pH和硫代巴比妥酸值都显著高于SV组(P<0.05)。肌原纤维蛋白的研究结果表明,在冻藏过程中,SV组的总巯基含量、二级结构的α-螺旋比例与内源荧光强度都高于TH组,冻藏120 d后表面疏水性的升高较TH组低9.31%。综上所述,冻藏时间的延长会加剧罗非鱼片品质的劣变,其中SV组品质的劣变程度弱于TH组。该研究结果可为罗非鱼片预制食品的发展和冻藏过程中的品质变化提供参考。展开更多
Polymeric perylene diimide(PDI)has been evidenced as a good candidate for photocatalytic water oxidation,yet the origin of the photocatalytic oxygen evolution activity remains unclear and needs further exploration.Her...Polymeric perylene diimide(PDI)has been evidenced as a good candidate for photocatalytic water oxidation,yet the origin of the photocatalytic oxygen evolution activity remains unclear and needs further exploration.Herein,with crystal and atomic structures of the self-assembled PDI revealed from the X-ray diffraction pattern,the electronic structure is theoretically illustrated by the first-principles density functional theory calculations,suggesting the suitable band structure and the direct electronic transition for efficient photocatalytic oxygen evolution over PDI.It is confirmed that the carbonyl O atoms on the conjugation structure serve as the active sites for oxygen evolution reaction by the crystal orbital Hamiltonian group analysis.The calculations of reaction free energy changes indicate that the oxygen evolution reaction should follow the reaction pathway of H_(2)O→^(*)OH→^(*)O→^(*)OOH→^(*)O_(2)with an overpotential of 0.81 V.Through an in-depth theoretical computational analysis in the atomic and electronic structures,the origin of photocatalytic oxygen evolution activity for PDI is well illustrated,which would help the rational design and modification of polymeric photocatalysts for efficient oxygen evolution.展开更多
基金supported by National Natural Science Foundation of China(No.523B2070,No.52225606).
文摘Polymeric perylene diimide(PDI)has been evidenced as a good candidate for photocatalytic water oxidation,yet the origin of the photocatalytic oxygen evolution activity remains unclear and needs further exploration.Herein,with crystal and atomic structures of the self-assembled PDI revealed from the X-ray diffraction pattern,the electronic structure is theoretically illustrated by the first-principles density functional theory calculations,suggesting the suitable band structure and the direct electronic transition for efficient photocatalytic oxygen evolution over PDI.It is confirmed that the carbonyl O atoms on the conjugation structure serve as the active sites for oxygen evolution reaction by the crystal orbital Hamiltonian group analysis.The calculations of reaction free energy changes indicate that the oxygen evolution reaction should follow the reaction pathway of H_(2)O→^(*)OH→^(*)O→^(*)OOH→^(*)O_(2)with an overpotential of 0.81 V.Through an in-depth theoretical computational analysis in the atomic and electronic structures,the origin of photocatalytic oxygen evolution activity for PDI is well illustrated,which would help the rational design and modification of polymeric photocatalysts for efficient oxygen evolution.
