| Infant supplementary nutrition package is made up of not less than 70% instant soybean powder,adding a variety of high-density micronutrients(vitamins and minerals),adding or not adding full-fat milk powder mixed packaging products,rich in nutrition.The supplements used in supplementary food for 6-36 months old infants can prevent malnutrition and promote the growth and development of infants.However,due to the high fat content in the nutrition package,lipid oxidation and metamorphism are easy to occur in the storage process.In this paper,the supplementary nutrition package for infants and young children was taken as the object of study,combined with gas chromatography-mass spectrometry(GC-MS)and ultra-high performance liquid chromatography-time-of-flight mass spectrometry(UPLC-Q-TOF-MS)and gas chromatography were used to analyze the lipid oxidation mechanism of supplementary nutrition package in infants and young children.This paper is divided into six parts.Headspace solid phase microextraction-gas chromatography-mass spectrometry(SPME-GC-MS)was used to analyze the changes of volatile compounds in infant nutrition packaging.A total of 65 volatile compounds were detected in the fresh nutrition package,including 10 alcohols,4 aldehydes and ketones,42 hydrocarbons,5 lipids and 4 other substances.9 volatile compounds were detected in the accelerated oxidation process,including 2-heptanone,(E)-2-heptenal,benzaldehyde,pentanol,2,2,4,4-tetramethyloctane,4-methyl-undecane,octadecane,O-tert-butylhydroxylamine and 3-hydroxy-2-methyl-gamma-pyrone.It was analyzed that the bad odor during the lipid oxidation of the nutrient package was formed by the interaction of hexanal,furfural,2-pentylfuran and 3-hydroxy-2-methyl-?-pyrone.UPLC-QTOF-MS was used to determine the chemical composition of fresh infant food supplement nutrition package and accelerated oxidation nutrition package.A total of 46 compounds were detected in the fresh nutrition package.Among them,23 compounds were identified in positive ion mode and 23 compounds were identified in negative ion mode.The substances identified in positive ion mode include 5 kinds of amino acids,10 kinds of organic acids,1 sulfide and 5 other kinds of substances;the substances identified under negative ion mode include 2 kinds of sulfides,13 kinds of flavonoids and their derivatives.And two other substances.From the identification results,it can be seen that there are more flavonoids,organic acids and amino acids in the infant food supplement package.The experimental data were imported into the MPP software to obtain 22 different compounds,including 7organic acids,3 amino acids,11 flavonoids and their derivatives,and 1 sulfide.It is inferred that these newly produced compounds are compounds in which a series of complex changes occur during the accelerated oxidation of the nutrient package.The fatty acid composition and content of the nutrient package were analyzed by gas chromatography.A total of 20 fatty acids,including 9 saturated fatty acids and 11 unsaturated fatty acids,including 7 monounsaturated fatty acids and 4polyunsaturated fatty acids,were detected.Among them,methyl myristate,methyl palmitate,methyl palmitate,methyl stearate and methyl oleate have a large content,and methyl stearate has the highest content.The content of saturated fatty acids generally showed an upward trend during the accelerated oxidation process,and the decline trend of long-chain polyunsaturated fatty acids was more obvious.During the oxidation process,the content of n-6 polyunsaturated fatty acids gradually decreased and decomposed to produce hexanal.Combined with the analysis of volatile components in the accelerated oxidation process,it was known that the content of hexanal gradually increased during the oxidation process,and consistent with the trend of peroxide value.It was concluded that the change of fatty acid composition and content was closely related to the change of volatile components,and the degree of oxidation of nutrient pack can be judged by the combination of changes in fatty acid composition and content and changes in volatile components.Gas chromatography-mass spectrometry(GC-MS)was used to detect the volatile components of infant food supplements in un-nitrogen-packed samples and nitrogen-packed samples and to perform principal component analysis.The results showed that the higher volatile substances in the un-nitrogen-packed samplesincluded hexanal,furfural,2-(2,6-dimethylheptyl)-cyclobutanone,3-tridecanone,terpineol,2-methyldecanol.The relative content of hexanal,furfural,2-heptanone and2-undecone was constantly increasing.The higher volatile substances in the nitrogen-packed samples was 2-decenal,2,2-dimethyloctanol,2-methyl-1-octanol,5-ethyl-2-nonanol,2,2,4,4-tetramethyloctane,3-methyl-5-propyl-decane,2,3-dimethyldecane.The relative content of aldehydes and ketones in the un-nitrogen-packed nutrition package samples during the accelerated oxidation process was generally higher than that of the nitrogen-packed nutrition package samples.Moreover,the time for producing aldehydes and ketones in un-nitrogen-packed samples was generally shorter than that of nitrogen-packed packaging samples.The peroxide value of unnitrogen packed nutrition package samples was always higher than that of nitrogen filled packaging.Therefore,combined with volatile components and peroxide value,we can speculate that nitrogen-filled packaging is more effective in delaying the oxidation of nutrients. |
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