The Effects Of Several Natural Spices On The Quality,flavor And Lipid Oxidation Of Salted Duck Eggs

Salted duck eggs have been favored by people in China and many Southeast Asian countries and regions,because of their traditional processing method,relatively long shelf life,and it has characteristics of oil exudate and special flavor.This study combined with the processing methods of salted duck eggs in China and Indonesia by adding several natural antioxidants in the pickling process.The additions include garlic oil,galangal extract,clove extract,and rosemary extract.The analysis of the impact of the additions on the eggs' characteristics,volatile flavor substances,lipid oxidation,and fatty acid composition showed that these additions improved the salted eggs' flavor and quality of the product.According to the results of the study,lipidomic analysis of salted duck eggs marinated with clove extract was analyzed.The main conclusions were as follows:The effects of garlic essential oil on the physical properties of salted eggs(water content,salt content,and oil exudation),the microstructure of eggshell and eggshell membrane and cooked egg yolk,fatty acid composition,and lipid oxidation of egg yolk were studied.The results showed that compared with the control group,the addition of 0.10% and 0.50%(v/v)garlic essential oil had a significant effect on the physical properties and microstructure of salted eggs.During salting,yolk supplemented with garlic oil had a lower TBARS value than those in the control group(P < 0.05).Furthermore,the contents of essential fatty acids such as gamma-linolenic acid,docosapentaenoic acid,docosahexaenoic acid,arachidonic acid,and linoleic acid in salted egg yolk were also significantly different from those in the control group during lipid oxidation.At the same time,the addition of garlic oil contributed to a more lax eggshell membrane,helping oil infiltration from the egg white to the egg yolk,which facilitated the formation of oil truffle texture by closer combination of egg yolk in the pickling process.The effects of galangal extract on the physical properties of salted eggs(water content,salt content,oil exudation),flavor components,lipid oxidation and antioxidant capacity were studied.Three groups were divided: the salted egg group containing 0.10% and 0.50%(w/v)galangal extracts,and the salted egg control group containing no galangal extracts.The results showed that compared with the control group,the addition of galangal extract could significantly reduce the lipid oxidation level during salting process.At the same time,the concentration and pickling time length of the extracts also had a significant effect on the fatty acid composition.On day 28 of the pickling process,the antioxidant activity of the eggs with 0.50%(w/v)galangal extract was significantly higher than that in the control group(P < 0.05).In addition,the analysis of the electronic nose showed that the galangal extract can make the salted egg produce unique flavor during the salting process.Finally the study revealed the effects of rosemary and clove extracts on salted eggs' fatty acid composition,lipid oxidation(TBARS,conjugated diene and p-anisidine value),antioxidant capacity(free radical scavenging ability and reduction ability),and volatile constituents.The results showed that the addition of these extracts significantly reduced the TBARS and p-anisidine value and decrease the content of conjugated diene during salting process.It also had a significant effect on fatty acid composition of salted egg yolk.For example,in the salty egg group with rosemary extract,the main fatty acid was palmitic acid,followed by(C18:2?-6),and arachidonic acid.After 14 days of pickling,the main fatty acids in the salted egg group with clove extract were oleic acid,palmitic acid,and arachidonic acid.The ratio values between polyunsaturated fatty acid and saturated fatty acid of the salted duck egg supplemented with clove extracts was significantly higher than that in the control group(P < 0.05),and the ?:6/?:3 ratio of the salted duck egg supplemented with clove extracts was significantly lower than that in the control group(P < 0.05).SPME GC-MS results showed that 22 and 25 volatile compounds were detected in salted eggs with 0.10% and 0.50%(w/v)rosemary extracts,and 46 and 37 volatiles were detected in salted eggs with 0.10% and 0.50%(w/v)clove extracts,respectively,in particular,the eugenol compound was also detected.Eugenol is the main bioactive component of clove and has extremely high antioxidant capacity.The result of electronic nose also showed that clove extract was the main substance that caused the change of salty egg flavor.Based on the above results,the salted egg yolks of the clove extracts preserved in salted eggs were analyzed by lipidomics and compared with the non-addition groups,and identified by UPLC-QE-MS/MS in positive and negative ion modes respectively.A total of 315 lipids were detected in the control group and the clove extract group.In the positive ion mode,the 10 subclasses of glycerolipids in the treated samples were significantly different(P < 0.05).The types with most varied lipid compositions were triglyceride and ceramides,followed by Cer G1,lyso phosphatidyl ethanolamine,diglyceride,and monosialodihexosyl ganglioside.The contents of lyso phosphatidyl ethanolamine,triglyceride,diglyceride,ceramides,monosialodihexosyl ganglioside,and Cer G1 in the yolk group of clove extract were significantly higher than those in the control group(P < 0.05).In the negative ion mode,the lipid content of 35 subclasses were significantly different(P < 0.05),including glycerolphospholipids,glycosphingolipids,and neutralglycosphingolipid.The types with most varied lipid compositions were phosphatidyl ethanolamine,followed by phosphatidyl choline,lyso phosphatidyl choline,and monosialodihexosyl ganglioside.The contents of phosphatidyl choline,lyso phosphatidyl choline,phosphatidyl ethanolamine,and monosialodihexosyl ganglioside in the yolk group of 0.50%(w/v)clove extract were significantly higher than those in the control group(P < 0.05),in which phosphatidyl choline and phosphatidyl ethanolamine were the main components of glycerolphospholipid.Additionally,these natural spices are widely available in Indonesia and are considered safe to be consumed,therefore this study will pave the way for improving salted duck eggs product,particularly in Indonesia.