Study On The Physicochemical Characteristics And Antioxidant Activity Of Products And Its Separated Components From Silver Carp Peptide By Maillard Reaction

This paper was based on our previous researches about silver carp peptide via Maillard reaction. The physicochemical characteristics and and antioxidant activity of Maillard reaction products (MRPs) prepared at high temperatures (>100℃) were analyzed deeply. In accordance with the polarity, the separation of MRPs with high antioxidant activity was separated by C18 sep-pak column and high performance liquid chromatography (HPLC). The relationship between antioxidant activity and polarity of MRPs had been studied. The contents of this paper were as follows:1.The changes of physicochemical characteristics and the formation of potentially harmful substances in MRPs prepared at different temperatures (90℃、120℃ and 140℃)were analyzed.The browning intensity and fluorescence of MRPs prepared under 90℃ system increased with reaction time. However, the browning intensity and fluorescence of MRPs prepared under 120℃ systems increased sharply at first and then increased slowly with reaction time; the browning intensity and fluorescence of MRPs prepared under 140℃ systems reached maximum at 1 h and then remained steady or decreased with reaction time,and these absorbances were much larger than that of 90℃ system indicating that high temperature promoted greatly the reaction process of Maillard reaction. Besides, the generation of potentially harmful substances in the MRPs prepared at different reaction conditions were different. In 90℃ systems, these substances accumulated with reaction time. In 140℃ systems, the contents of HMF reached maximum at first and then decreased with reaction time; however, the content of acrylamide increased with reaction time. This showed that the contents of harmful substances were not only related to the process of reaction, but also with its own stability probably.2.The antioxidant activity of MRPs prepared at different reaction conditions was analyzed by useing DPPH and ABTS radical scavenging, total antioxidant activity (FRAP), Fe2+ chelating ability and the capacity of repairing oxidant damage to cells. The free radical scavenging capacity of MRPs generated under 90℃ increased with reaction time. The scavenging capacity of MRPs generated under 120℃ increased sharply and then increased slowly with prepared time;The scavenging capacity of MRPs generated under 140℃ increased to a maximum at the initial 1h. The trends of the antioxidant ability of MRPs prepared at all temperatures were similar with the trends of A294nm, A420nm and fluorescence, indicating that the antioxidant activity of MRPs was related to the process of Maillard Reaction. However, the ability of Fe2+chelating of MRPs prepared under 90℃(3h) was the strongest. It indicated the major substances having chelating ability were formed in the initial reaction stage. As can be seen from the indicators measured, MRPs prepared at high temperature has strong antioxidant activity; but its ability to chelate Fe2+ was lower than MRPs prepared under 90℃.Besides, the repair of damaged cells by MRPs generated under 90℃ increased with reacton time. When the concentration of MRPs prepared under 120℃ and 140℃ reached above 150μg/mL, the repair capacity of oxidant damage in cells was significantly improved (P<0.05). However, the repair capacity decreased with the extension of prepared time.3. In accordance with the polarity, the separation of MRPs with high antioxidant activity was separated by C18 sep-pak column and high performance liquid chromatography (HPLC). Then the relationship about antioxidant activity of each component and its polarity had been studied. At first, MRPs produced under 140℃(1h) was separated by solid-phase extraction to generate five components. After freeze drying, the content of each component varied with preparation of temperatures. F-2 had the highest content and F-5 had the lowest content. In terms of antioxidant activity, F-4 had the strongest free radical scavenging and total antioxidant capacity. Thus, it could be deduced that the less polar substances played an important role in the antioxidant activity of MRPs. F-4 was further separated by HPLC to generate six fractions, and the f-6 exihibited the strongest antioxidant activity among all fractions. But the antioxidant activity of six fractions were lower than original F-4,suggesting that the interaction between six fractions may be able to improve the antioxidant capacity.