Change Patterns And Interactions Of Trace Concomitants In High Oleic Rapeseed Oil During Frying

High oleic rapeseed oil is a new type of rapeseed oil with more than 72% oleic acid content,which has good application prospects in the field of frying oil due to its special fatty acid composition,rich trace concomitants and good oxidative stability.However,there are few studies on the frying performance of high oleic rapeseed oil,the changes of its main trace concomitants during frying and the types of interactions were not reported.Therefore,this study analyzed the frying properties of high oleic rapeseed oil and the interaction mechanism of its trace concomitants in the frying process,which could provide theoretical guidance for high oleic rapeseed oil as frying oil.The details are as follows:First,the fatty acid composition,basic physicochemical indexes acid value(AV),peroxide value(POV)and anisidine value(PAV),frying indexes total polar substance(TPC),antioxidant capacity indexes FRAP,ABTS,DPPH of three commonly used frying oils prepared by two processes,hot-pressed and cold-pressed,were compared for 18 h continuous frying experiments.three free radical scavenging and other performance indexes.The results showed that cold pressed high oleic rapeseed oil had the lowest AV(0.26 mg/g)and POV(1.96 g/100 g)and the strongest FRAP free radical scavenging ability(344.31 μmol TE/kg);hot pressed high oleic rapeseed oil had the lowest PAV(152.48)and the latest time to reach the upper limit of TPC 27%(18 h),which was significantly better than the other three frying oils.It proved that the frying performance of high oleic rapeseed oil was good.Secondly,the changes of 3-MCPDE,glycidyl ester,acrylamide and benzo(a)pyrene,and trace concomitants of tocopherol,phytosterol and squalene in hot pressed and cold pressed rapeseed oils were examined during frying,and the changes of trace concomitants in high oleic rapeseed oils during frying were comprehensively analyzed with the frying characteristics.The experimental results showed that the highest Ba P,3-MCPDE and GEs in hot pressed high oleic rapeseed oil reached 1.57 μg/kg,1.93 mg/kg and 10.07 mg/kg,respectively,while the highest Ba P,3-MCPDE and GEs in cold pressed high oleic rapeseed oil reached 2.21 μg/kg,2.68 mg/kg and 4.03 mg/kg,respectively,during frying.In addition,the loss of squalene,total phenols,α-tocopherol,γ-tocopherol,rapeseed sterols and glutathione during frying was greater than 50%,which were the trace concomitants mainly involved in the frying reaction.Based on the correlation analysis,it was found that the DPPH radical scavenging ability was significantly correlated with the contents of α-tocopherol,γ-tocopherol and rape oil sterols in all time periods of frying with the coefficients greater than 0.80,which proved that the antioxidant ability of high oleic canola oil during frying was most correlated with the contents of α-tocopherol,γ-tocopherol and rape oil sterols,the three trace concomitants.Finally,α-tocopherol,γ-tocopherol and rapeseed sterol were combined in two combinations to evaluate the interaction mechanism of these trace concomitants in the frying process of high oleic canola oil after the removal of concomitants using Bliss evaluation model.The experimental results showed that α-tocopherol and rapeseed sterol were synergistic antioxidants from 0 to 11.6 h,and became antagonistic antioxidants after 11.6 h.γ-tocopherol and rapeseed sterol showed synergistic antioxidant effects during frying,and their synergistic effects reached the maximum at 6 h.The experimental value of DPPH scavenging capacity was192.11 μmo LTE/100 g,which was 105% higher than the theoretical value at this time.The synergistic effect of α-tocopherol and γ-tocopherol showed synergistic antioxidant effect during frying,and their synergistic effect reached the maximum at 9 h of frying,and the experimental value of DPPH scavenging capacity was157.67 μmo LTE/100 g at this time,which was 94% higher than the theoretical value at this time.In summary,this thesis provides a systematic study on the frying performance of high oleic acid rapeseed oil and the change pattern and interaction mechanism of trace concomitants in the frying process,and provides a theoretical basis for the change pattern of trace concomitants in high oleic acid rapeseed oil during frying.