Analysis Of Egg Flavour Characteristics And Flavour Components During Storage

In order to explore the characteristic egg flavor, this subject combines the electronic tongue and electronic nose to analyze the changes of egg tastes and odors during storage periods and the difference between eggs of normal and fermented feeds. What’s more, some physical and chemical indicators, fat acids, amino acids and volatile components of eggs during storage are discussed in this article, aiming to lay a foundation for further study on the egg flavor. The main results are as follows:(1) Electronic tongue and electronic nose were used to evaluate the effects of fermented and normal feeds on egg flavor. Electronic sensory indicator values were analyzed by cluster analysis and significance analysis. Results of electronic tongue showed that bitterness,astringency, saltiness and umami richness of egg yolk have extremely significant differences(P < 0.01).Bitterness aftertaste and astringency aftertaste had significant differences(P < 0.05). Taste output values changed between 15.05% and 84.00%, except sourness, which changed 1.04%.There were significant differences between two groups of egg white. Bitterness and its aftertaste, astringency, umami richness of white were extremely significant(P < 0.01).Sourness, freshness and astringency aftertaste had significant differences(P < 0.05).The taste output values of white changed between 28.15% and 625.00%, except sourness(2.40%), uma mi(2.08%), and saltiness(4.44%). Results of electronic nose showed that egg white of fermented feed differ from the normal feed obviously, and there is little difference between two yolk groups. The combined method of electronic nose and electronic tongue can discriminate fermented feed eggs from ordinary feed eggs objectively and quickly.(2) Eggs were stored at 4±1℃ for 40 days, sampled every 10 days, the same with 23±1℃. The output values of electronic tongue were analyzed with variance analysis, the electronic nose with principal component analysis(PCA). The electronic tongue results showed that during storage period, the bitterness, bitterness aftertaste, umami, umami richness, and sourness output values of egg white change significantly. Bitterness output values, umami output values of egg whites stored at 4±1℃. and 23±1℃.changed most at 20 th day and 10 th day respectively. The sourness output values of two groups changed most at the 30 th day. The bitterness, bitterness aftertaste, umami and sourness output values of egg yolk changed significantly during storage. Bitterness output values of yolks stored at 4±1℃ and 23±1℃ changed most at the 10 th day. The largest changes of umami appeared at the 20 th day. Sourness output values of two groups changed most at the 30 th day. The results of the electronic nose showed that egg whites of different storage time have different odor characteristics at 4±1 ℃. Egg whites of 23±1 ℃ presented certain odor changing rule. Egg yolks of different storage time had different odor traits at 4±1℃. Egg whites of 23±1℃ presented certain odor changing rule as the extending of storage time.(3)At 4±1℃, stored to 30 th days, unsaturated fatty acids in total lipid and phosphatide of egg yolk, had declined obviously, afterwards little change was found,and the same with saturated fatty acids. So fatty acids changes had little effect on flavor changes. At 23±1℃, both unsaturated fatty acids and saturated fatty acids of total lipids had little change. Unsaturated fatty acids in phospholipids declined slightly when stored for 20 days, changed little from 20 d sys to 50 days, and decreased obviously at 60 th days. Serious degradation may occur at this time. Compared to storage at 23±1℃, amino acid contents in egg white and egg yolk reduced more when stored for180 days at 4±1 ℃. Egg white contains rich amino acids, more easily affected by the storage time.(4) When stored at 23±1℃ for 30 days, various volatile compounds in egg yolk reached their peak values, explaining the richest flavor quality of egg yolk. When stored at 4±1℃, various volatile compounds in egg yolk reached their peak values at 120 d to 180 d. Aldehydes are important flavor compounds in egg yolk, mainly the medium and long carbon chain length of aldehydes. We found that1,2-Benzenedicarboxylic acid, bis(2- methylpropyl) ester is a characteristic flavor compound of boiled eggs. Egg white had less volatile compounds than egg yolk, and aromatic compounds were main compounds significantly higher than other compounds. Also all kinds of compounds changed insignificantly. Storage time and temperature had a little effects on egg white flavor quality.