| Chinese red pepper?Zanthoxylum bungeanum Maxim.?,belonging to the genus Zanthoxylum of the family Rutaceae and native to Eastern China,the pericarp was primarily used as a peppery spice.The pepper leaf,which have not been made full use of,was usually be discarded,Zanthoxylum bungeanum Maxim.leaf?ZML?alcohol extract were identified by HPLC-MS/MS,chlorogenic acid,hyperoside,and quercitin were the major bioactive compounds.In this study,we added ZML alcohol extract to salted silver carp?Hypophthalmichthys molitrix?,and then identified the antioxidant effect of ZML alcohol extract.Lipid oxidation is an important pathway of flavor development in salted fish during salting,drying,and storage.It also has adverse effects on the quality of meat products because of the deterioration in color,flavor,texture,and the nutritional value of these foods.Lipid oxidation of salted fish in an entire fillet has been reported by many researchers.In fact,the lipid content of the ventral muscle was significantly higher than that of the dorsal muscle in fish.Therefore,the aim of this study was to determine the antioxidant effect of ZML alcohol extract against lipid oxidation in the dorsal and ventral muscle of salted silver carp during processing.And the collected all the main results as following:1.Extraction,component identification,and antioxidation of ZML alcohol extractThe ZML polyphenols were extracted by ultrasound-assisted extraction.The optimized conditions were a solid-to liquid ratio of 1:20,65%?v/v?ethanol,a ultrasound powder of 200 W,and a ultrasound time of 30 min.Under the above-mentioned conditions,the extractpolyphenol content was 68.6 mg/g.Here we investigated the adsorption and desorption on macroporous resins as a means of purifying the ZML polyphenols.D101macroporous resin was verified to offer the best adsorption capacity?37.72 mg/g?and desorption ratio?91.86%?for ZML alcohol extract amony the five macroporous resins investigated.The concentration of the sample solution was 1.0 mg/mL,pH 4.0,and the feading folw rate was 2 BV/h.Desorption solvent was 80%ethanol solution,an eluted flow of 2 BV/h.After desorption,the polyphenol content of ZML alcohol extract was up to 555.0 mg/g.The ZML polyphenols were analysed with a high performance liquid chromatography-liquid chromatography/mass spectrometry?HPLC-LC/MS?system,and eight polyphenols were identified?quinic acid,chlorogenic acid,5-feruloylquinic acid,rutin,hyperoside,quercitin-3-arabinoside,quercitrin,and vitexin?.Chlorogenic acid?2.67 g/100g?,hyperoside?8.25 g/100g?,and quercitrin?11.62 g/100g?were the major bioactivesin the ZML alcohol extract.The ZML alcohol extract contains high amounts of phenolic compounds possessing high total antioxidant capacity and hydroxyl,1,1-dipheny-2-picrylhydrazyl?DPPH?free radical scavenging activity.2.Effect of ZML phenolic extract on the physicochemical properties and sensory qualities of the dorsal and ventral muscle of salted fish during processingZML alcohol extract was investigated as a natural antioxidant for thephysicochemical propertiesand sensory qualities of salted silver carp?Hypophthalmichthys molitrix?throughout salting and drying.Both dorsal and ventral muscles were examined for differences in moisture content,total lipid content,pH value,and total bacterial count except salt content.The moisture content in the dorsal muscle was significantly higher than in the ventral muscle?p<0.05?while there was no difference in the salt content between the dorsal and ventral muscle?p>0.05?.There was no significant difference in the salt and moisture content among the control and treatments in either dorsal or ventral muscle?p>0.05?.The treatments with ZML alcoholl extract have lower pH values and higher lipid contents both in dorsal and ventral muscle;the total bacterial count in dorsal and ventral muscle was growing during the processing time,the treatments with ZML alcohol extract had lower total bacterial count,and the treatments with more ZML alcohol extract had the lower total bacterial count compared to the groups with less ZML alcohol extract.The addition of ZML alcohol extract significantly improved the umami,color,and flavor of salted fish both in the dorsal and ventral muscle compared to the control?p<0.05?.However,there was no significant difference among the control and treatments with different ZML alcohol extract amounts?p>0.05?except the treatment with 0.045%ZML alcohol extract?p<0.05?,so the treatments with ZML alcohol extract had the improved quality both in the dorsal and ventral muscle.The physicochemical properties and sensory qualities of processed salted fish could be improved with the amount of 0.030%extract in the dorsal muscle and 0.045%extract in the ventral muscle.3.Effect of ZML phenolic extract on the lipid oxidation of the dorsal and ventral muscle of salted fish during processingZML alcohol extract was investigated as a natural antioxidant for the lipid stability of salted silver carp throughout salting and drying.Both dorsal and ventral muscles were examined for conjugated dienes value,peroxide value?POV?,thiobarbituric acid reactive substances?TBARS?value,the hexanal content,and lipoxygenase?LOX?activity.According to the results,conjugated dienes value,POV,TBARS value,the hexanal content,and LOX activity in the ventral muscle were significantly higher than those of the dorsal muscle?p<0.05?.In the treatments with ZML alcohol extract,conjugated dienes value,POV,TBARS value,the hexanal content,and LOX activity were significantly lower?p<0.05?during processing both in the dorsal and ventral muscles.Therefore,the degree of lipid oxidation of ventral muscle was higher than the dorsal muscle?p<0.05?.In the treatments with ZML alcohol extract,the conjugated dienes value,POV,TBARS value,the hexanal content,and LOX activity were significantly lower?p<0.05?during processing both in the dorsal and ventral muscles than the control.The optimized amount of ZML alcohol extract was 0.030%extract in the dorsal muscle and 0.045%in the ventral muscle.4.Effect of ZML phenolic extract on endogenous antioxidant enzymes activities of the dorsal and ventral muscle of salted fish during processingThe GSH-Px,SOD and CAT activities decreased markedly both in dorsal and ventral muscle during the salting and dryingprocessing.The addition of the ZML alcohol extract and the polyphenols increased these enzyme activities.Compared to the ZML alcohol extract treatment,both dorsal and ventral muscles of salted fish with chlorogenic acid and hyperoside had higher activities of the antioxidant enzymes?p<0.05?.By comparison,quercitrin treatment expressed a weaker protective ability than the ZML alcohol extract treatment.From the perspective of the structure,3'-and 4'-hydroxyl groups that have the ortho-dihydroxy structure in the B ring,becoming effective hydrogen donors with high antioxidant capacity,and 1-hydroxyl and 1-carboxylate groups were likely to be the effective hydrogen donors to scavenge O2·-and OH·in the A ring.Based on the possible considerations,chlorogenic acid showed effective antioxidant activity.5.Effect of ZML phenolic extract on volatile flavor compoundsof the dorsal and ventral muscle of salted fish during processingSPME-GC-MS separation was used to identify volatile flavor compounds of dorsal and ventral control and ZML alcohol extract treatmemt during processing.39 kinds of compounds have been identified in dorsal muscle of control group final products,including 8 kinds of alkanes,1 alkenes,2 kinds of benzenes,4 kinds of aldehydes,12 kinds of alcohols,3 kinds of ketones,6 kinds of acids,1 ethers,1 oxime,1 easter.While 31 kinds of compounds in ventral muscle of control group final products,including 5 kinds of alkanes,2 alkenes,1 benzenes,5 kinds of aldehydes,6 kinds of alcohols,3 kinds of ketones,5 kinds of acids,1 ethers,1 oxime,1 easter.When ZML alcohol extract was added,31 kinds of compounds have been identified in dorsal muscle of treatment group final products,including 11 kinds of alkanes,2 kinds of alkenes,2 kinds of benzenes,4 kinds of aldehydes,6 kinds of alcohols,2 kinds of ketones,2 kinds of ethers,1 oxime,1 easter,the total number of compounds in dorsal muscle of treatment group was 8 kinds of compounds less than the control.And 31 kinds of compounds were identified in ventral muscle of treatment group final products,10 kinds of alkanes,2 kinds of alkenes,2 kinds of benzenes,3 kinds of aldehydes,8 kinds of alcohols,2 kinds of ketones,2 kinds of ethers,1 oxime,1 easter,the total number of compounds in ventral muscle of treatment group was same as that of the control.Alkames and alkenes,which attributed to the earthy smell of salted fish,was less in treatment final salted fish both in dorsal and ventral muscle after ZML alcohol extract added.Ketones and benzenes,mainly produced by lipid oxidation,were also decreased in treatment compared to the control.And the relative content of oxime which was a chemical reaction between aldehydes or ketones and hydroxylamine was increased?p<0.05?. |
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