| Mustard is a famous Chinese vegetable.It can be eaten in fresh,or in the pickled form.Pickled mustard was delicious and loved by the public.However,there is little information on the changes of nutrition and phenolic content in mustard during pickling process.In this study,leaf mustard was pickled by dry pickling with two salt concentration(5% and 8%).The physicochemical and nutritional components of in leaf mustard were mearured during pickling process.The antioxidant effects of pickled mustard extract and powder on the minced pork during refrigerated storage were investigated.The main contents of this paper are as follows:(1)Effect of pickling on some chemical compositions contents of leaf mustard was investigated.The results showed that the nutritionals of mustard have changed during pickling,contents of moisture,protein and starch decreased significantly(p<0.05),ash content increased significantly(p<0.05),content of crude fat increased first and then decreased(p<0.05),and the content of crude fiber was not changed significantly(p>0.05).Nitrite content increased first and then increased and then increased.However,nitrite content of mustard is much lower than the national standard.(2)Changes in the contents of free and bound phenolic,free and bound flavonoid,DPPH free radical scavenging activity,reducing power and total antioxidant activity of the extracts from leaf mustard pickled with different concentrations were studied during pickling.It has been found that mustard pickled with 5% salt for 30 days has the highest polyphenols content and the highest antioxidant activity.A high correlation was observed between the total antioxidant activity and the contents of polyphenol and flavonoid,the correlation coefficients were 0.996(p <0.01)and 0.959(p <0.01),respectively.Also,a high correlation has been found between DPPH free radical scavenging activity and the content of polyphenol and flavonoid,the correlation coefficients were 0.980(p <0.01)and 0.943(p <0.01),respectively.The changes of phenolic constituents in mustard during pickling were analyzed by using high-performance liquid chromatography(HPLC),and eight phenolic acids in all extracts were identified as protocatechuic acid,chlorogenic acid,caffeic acid,p-hydroxybenzoic acid,vanillic acid,p-coumaric acid,ferulic acid and erucic acid,the contents of most of the phenolic acids significantly changed during pickling.The contents of catechuic acid,p-coumaric acid,ferulic acid and erucic acid were increased significantly(p <0.05),chlorogenic acid decreased significantly(p <0.05),whereas,caffeic acid,p-hydroxybenzoic acid and vanillic acid were notchanged significantly(p> 0.05).(3)Thiobarbituric acid-reactive substances(TBARS)value,peroxide value(POV)and conjugated diene were used to evaluate the antioxidant activity of the ethanolic extracts from leaf mustard pickled with 5% salt for 30 d in raw ground pork during storage at(4 ± 1)℃ for 7 days.The results showed that the pickled mustard extract can effectively inhibit lipid oxidation,prolong the storage time of refrigerated raw minced pork.From the change of TBARS value,the antioxidant effect of 2% pickled mustard extract was better than the other two concentrations of pickled mustard extract.Also,the antioxidant activity of the dried powder and its ethanolic extract from the leaf mustard pickled with 5% salt for 30 days on oxidative stability of refrigerated cooked minced pork was studied.The antioxidant effect was evaluated by conjugated diene content,peroxide value and TBARS value.The results indicated that the pickled mustard powder and its ethanolic extract can effectively inhibit lipid oxidation in refrigerated cooked minced pork.The antioxidant effect of the extract of the pickled mustard was less than the pickled mustard powder.0.2% pickled mustard powder had a similar effect on the antioxidant effect of 0.02% Vc on the cooked minced pork,and increasing the concentration of the powder to 0.4% did not significantly increase the antioxidant effect of the cooked minced pork. |
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