This study evaluated the effects of worm infection on the volatile components,total phenolic compounds,and antioxidant capacities of Gomphidius rutilus.G.rutilus without worms(GW),G.rutilus infected by a small amount ...This study evaluated the effects of worm infection on the volatile components,total phenolic compounds,and antioxidant capacities of Gomphidius rutilus.G.rutilus without worms(GW),G.rutilus infected by a small amount of worms(GS;infected area<50%),and G.rutilus infected by a large amount of worms(GL;infected area>50%)were investigated.The volatile components of G.rutilus were analyzed by simultaneous distillation–extraction(SDE)and headspace solid-phase microextraction(HS-SPME)using gas chromatography–mass spectrometry(GC–MS).A total of 17 and 19 types of volatile compounds were detected,including ketones,alcohols,benzene,alkenes,aldehydes,esters,acids,and alkanes.Alcohols comprised the most abundant compound in GL,GS,and GW.The relative content of 1-octen-3-ol was the highest in all mushrooms.The concentration of eight-carbon(C8)compounds relative to the total volatile compounds varied widely,ranging from 40%(GW)to 64.34%(GS)and 84.42%(GS)and to 91.59%(GL),respectively,among the three samples.The antioxidant capability and the total phenolic contents of G.rutilus were evaluated in this study.The highest total phenolic content(TPC)of 192.23 mg GAE/g was found in GL,which differed significantly(P<0.05)from the latter two samples,whereas the lowest value of 156.11 mg GAE/g was found in GW.ABTS radical cation scavenging activity,FRAP ferric reducing antioxidant capacity(FRAP)radical scavenging activity,and oxygen radical absorbance capacity(ORAC)were investigated to screen the antioxidant properties of extracts.The contents of total phenolic compounds and their antioxidant capacities in vitro showed significant correlations(P<0.01).Among the three types of samples,the phenolic compounds of GL exhibited the highest antioxidant capacity,showing the values of 0.089 mM TE/g for ABTS,0.949 mM Fe^2+E/g for FRAP,and 1.952 M TE/g for ORAC.However,regarding the total antioxidant capacity,GS exhibited the highest antioxidant capacity,showing the values of 0.002648 mM TE/g for ABTS,0.004437 mM Fe^2+E/g for FRAP,and 0.256μM TE/g for ORAC.In conclusion,HS-SPME was more suitable for the extraction of volatile aroma components from G.rutilus.GL had the most abundant aroma components.GL had the highest TPC and antioxidant capacity compared with those of GS and GW,whereas GS showed the opposite results.Interestingly,GS was found to have the highest total antioxidant capacity in vitro.Based on these measured indicators,worm infection had no negative effect on the quality of G.rutilus.Therefore,worm-infected G.rutilus can also be consumed by humans.展开更多
This study investigates the volatility in daily stock returns for Total Nigeria Plc using nine variants of GARCH models:sGARCH,girGARCH,eGARCH,iGARCH,aGARCH,TGARCH,NGARCH,NAGARCH,and AVGARCH along with value at risk e...This study investigates the volatility in daily stock returns for Total Nigeria Plc using nine variants of GARCH models:sGARCH,girGARCH,eGARCH,iGARCH,aGARCH,TGARCH,NGARCH,NAGARCH,and AVGARCH along with value at risk estimation and backtesting.We use daily data for Total Nigeria Plc returns for the period January 2,2001 to May 8,2017,and conclude that eGARCH and sGARCH perform better for normal innovations while NGARCH performs better for student t innovations.This investigation of the volatility,VaR,and backtesting of the daily stock price of Total Nigeria Plc is important as most previous studies covering the Nigerian stock market have not paid much attention to the application of backtesting as a primary approach.We found from the results of the estimations that the persistence of the GARCH models are stable except for few cases for which iGARCH and eGARCH were unstable.Additionally,for student t innovation,the sGARCH and girGARCH models failed to converge;the mean reverting number of days for returns differed from model to model.From the analysis of VaR and its backtesting,this study recommends shareholders and investors continue their business with Total Nigeria Plc because possible losses may be overcome in the future by improvements in stock prices.Furthermore,risk was reflected by significant up and down movement in the stock price at a 99%confidence level,suggesting that high risk brings a high return.展开更多
基金This work was supported financially by Edible mushroom resources exploitation and the key technology development in efficient processing,“National Key R&D Program of China”[Project No.2018YFD0400200]Liaoning Province,Shenyang Agricultural University,high-end talent introduction fund project[grant number SYAU20160003].
文摘This study evaluated the effects of worm infection on the volatile components,total phenolic compounds,and antioxidant capacities of Gomphidius rutilus.G.rutilus without worms(GW),G.rutilus infected by a small amount of worms(GS;infected area<50%),and G.rutilus infected by a large amount of worms(GL;infected area>50%)were investigated.The volatile components of G.rutilus were analyzed by simultaneous distillation–extraction(SDE)and headspace solid-phase microextraction(HS-SPME)using gas chromatography–mass spectrometry(GC–MS).A total of 17 and 19 types of volatile compounds were detected,including ketones,alcohols,benzene,alkenes,aldehydes,esters,acids,and alkanes.Alcohols comprised the most abundant compound in GL,GS,and GW.The relative content of 1-octen-3-ol was the highest in all mushrooms.The concentration of eight-carbon(C8)compounds relative to the total volatile compounds varied widely,ranging from 40%(GW)to 64.34%(GS)and 84.42%(GS)and to 91.59%(GL),respectively,among the three samples.The antioxidant capability and the total phenolic contents of G.rutilus were evaluated in this study.The highest total phenolic content(TPC)of 192.23 mg GAE/g was found in GL,which differed significantly(P<0.05)from the latter two samples,whereas the lowest value of 156.11 mg GAE/g was found in GW.ABTS radical cation scavenging activity,FRAP ferric reducing antioxidant capacity(FRAP)radical scavenging activity,and oxygen radical absorbance capacity(ORAC)were investigated to screen the antioxidant properties of extracts.The contents of total phenolic compounds and their antioxidant capacities in vitro showed significant correlations(P<0.01).Among the three types of samples,the phenolic compounds of GL exhibited the highest antioxidant capacity,showing the values of 0.089 mM TE/g for ABTS,0.949 mM Fe^2+E/g for FRAP,and 1.952 M TE/g for ORAC.However,regarding the total antioxidant capacity,GS exhibited the highest antioxidant capacity,showing the values of 0.002648 mM TE/g for ABTS,0.004437 mM Fe^2+E/g for FRAP,and 0.256μM TE/g for ORAC.In conclusion,HS-SPME was more suitable for the extraction of volatile aroma components from G.rutilus.GL had the most abundant aroma components.GL had the highest TPC and antioxidant capacity compared with those of GS and GW,whereas GS showed the opposite results.Interestingly,GS was found to have the highest total antioxidant capacity in vitro.Based on these measured indicators,worm infection had no negative effect on the quality of G.rutilus.Therefore,worm-infected G.rutilus can also be consumed by humans.
文摘This study investigates the volatility in daily stock returns for Total Nigeria Plc using nine variants of GARCH models:sGARCH,girGARCH,eGARCH,iGARCH,aGARCH,TGARCH,NGARCH,NAGARCH,and AVGARCH along with value at risk estimation and backtesting.We use daily data for Total Nigeria Plc returns for the period January 2,2001 to May 8,2017,and conclude that eGARCH and sGARCH perform better for normal innovations while NGARCH performs better for student t innovations.This investigation of the volatility,VaR,and backtesting of the daily stock price of Total Nigeria Plc is important as most previous studies covering the Nigerian stock market have not paid much attention to the application of backtesting as a primary approach.We found from the results of the estimations that the persistence of the GARCH models are stable except for few cases for which iGARCH and eGARCH were unstable.Additionally,for student t innovation,the sGARCH and girGARCH models failed to converge;the mean reverting number of days for returns differed from model to model.From the analysis of VaR and its backtesting,this study recommends shareholders and investors continue their business with Total Nigeria Plc because possible losses may be overcome in the future by improvements in stock prices.Furthermore,risk was reflected by significant up and down movement in the stock price at a 99%confidence level,suggesting that high risk brings a high return.
