Effects Of Cooking Methods On Antioxidant Capacity And Glucosinolates In Red Cabbage

Red cabbage is one of the important vegetables of cruciferous,rich in anthocyanins,carotenoids,ascorbic acid,phenolic acid and glucosinolate and other nutrients,with anti-cancer,anti-tumor a variety of biological activity.Red cabbage in China and the world is widely cultivated and edible.Before consumption,red cabbage will go through a variety of cooking methods.In this paper,the effects of different cooking methods(boiled,steamed,microwave,stir-fried and fried)on the basic components(crude protein,crude fat,crude fiber and ash),color difference,nitrate,nitrite were studied and(DPPH,FRAP,ABTS and ORAC)were used to determine the effect of different cooking methods on the antioxidant properties of red cabbage and the effects of antioxidant substances(anthocyanins,carotenoids,ascorbic acid and phenols)were studied.A new liquid mass spectrometry method was used to determine the change of glucosinolate content in red cabbage after different Chinese cooking methods.The main findings are as follows:(1)In addition to boiling,microwaving and frying increase the content of crude fat and crude fiber,the crude fat,crude fiber,crude protein and ash content are reduced by boiling,steaming,microwaving,frying and frying.With the increase of cooking time,the ash content decreased,the crude fiber content increased,the crude fat increased first and then decreased,and the ash content increased first and then increased.The results of single factor experiments showed that the nitrate content increased by stir-frying(27.87%),and the content of nitrate was decreased 16.67%-49.91 by boiling,microwave,steaming and frying.The nitrite content was increased by 52.12%-408.51%after different cooking methods,of which the largest increase was frying.For the color difference,the L*value is increased except for the boil,the other is reduced;a*is boiled,steamed and fried to increase,the other is reduced;b*all the cooking methods let it be reduced.The L*and b*values increase as the time of cooking increases,and the a*value decreases as the time of cooking increases.(2)Single factor experiments showed that total anthocyanins,total carotenoids,ascorbic acid,total phenols and free phenolic acids were significantly reduced after Chinese cooking.Frying and frying resulted in a significant reduction in antioxidant properties,but steaming and microwaving retained the most healthy compounds,and therefore could be the best way to cook red cabbage.Extending the cooking time will cause more damage to the antioxidant.The total content of antioxidants was reduced by 21.45%-60.58%,total carotenoids decreased by 9.07%-41.63%,ascorbic acid decreased by 21.83%-93.13%,total phenol decreased by 26.20%%To 56.34%,22.77%-88.67%for coumaric acid,12.77%-81.20%of protocatechuic acid and 8.98%-84.96%for caffeic acid.The reduction of p-hydroxybenzoic acid and ferulic acid is small.The effect of different cooking time on the antioxidant substance of red cabbage:the decrease of anthocyanin was 11.54%-78.65%,the decrease of total carotenoid was 15.89%-44.87%,the decrease of ascorbic acid was 0.01%-94.29%The reduction was 15.44%-71.64%,the protocatechamic acid was 16.88%-74.00%,the coumaric acid was 49.33%-82.67%,the p-hydroxybenzoic acid 41.12%-94.38%,ferulic acid 49.33%-77.60%and caffeic acid 4.34%-84.73%.(3)Four kinds of evaluation methods were used:ABTS radical scavenging effect,DPPH radical scavenging effect,FRAP iron reduction power and ORAC oxygen free radical absorptive capacity were used to evaluate the antioxidant capacity of all citrus fruits,antioxidant capacity and antioxidant substances for correlation analysis.The antioxidant activity of red cabbage was evaluated by the APC index(Antioxidant potency composite index).It was found that the antioxidant activity index of red cabbage was the lowest after frying,which indicated that the DPPH scavenging free radical capacity,ABTS free radical scavenging ability and ORAC oxidation free radical absorption capacity of the integrated antioxidant activity of the weakest.And the antioxidant activity index of red cabbage after boiling is the highest.The contents of total anthocyanins,total carotenoids,ascorbic acid,total phenolics,protocatechuic acid,caffeic acid,coumaric acid,ferulic acid and p-hydroxybenzoic acid were compared with DPPH,FRAP and ORAC(p<0.01),indicating that the total anthocyanins,total carotenoids,ascorbic acid,total phenol,protocatechuic acid,caffeine,and caffeine were found in purple cabbage.The results showed that the antioxidant capacity was positively correlated with the antioxidants.The more content of total anthocyanins,total carotenoids,ascorbic acid,total phenolics,protocatechuic acid,caffeic acid,coumaric acid,ferulic acid and p-hydroxybenzoic acid the stronger the antioxidant capacity(4)Ten glucosinolates were successfully identified in red cabbage by the LC-MS/MS method.The obtained fragment ion[SO4H]-for m/z 97 was used in scan mode to determine the masses of the glucosinolate precursor ion[M-H]-which was further validated by the largely known chromatographic behavior of the resulting intact glucosinolates.We first investigated the effects of different cooking methods(boiling,microwaving,steaming,frying and stir-frying)and different boiling times on the levels of glucosinolates in red cabbage by this new method.Compared with raw red cabbage,reductions of 9.61%-87.37%,13.41%-98.53%,42.57%-95.48%,29.18%-83.27%,6.79%-83.94%,5.38%-95.86%,0.32%-79.94%,16.30%-95.88%and 13.70%-75.06%in 4-methoxyglucobrassicin,neoglucobrassicin,glucoalyssin,glucobrassicin,glucoraphanin,glucoiberin,progoitrin,gluconapin and sinigrin content,respectively,were observed after cooking.Decreases of 32.36%,24.83%,25.27%,81.11%and 84.29%in total glucosinolates were observed after boiling,microwaving,steaming,frying and stir-frying,respectively.Frying and stir-frying caused a significant reduction of glucosinolate content.This study found this plant to be a rich source of glucosinolates,but their levels were easily reduced by cooking.