Study On Fat Oxidation Mechanism Of YYB During The Storage Process

YYB,a supplement with Type I instant soybean flour as the main matrix,which contains vitamins,minerals and a variety of micronutrients.As such,they are nutrientrich and effective in preventing symptoms of malnutrition such as anaemia,growth retardation and low body weight in infants and young children.However,the high fat content in the food matrix makes the YYB highly susceptible to lipid oxidation during production and storage.In this experiment,the oxidative stability of YYB at different stages of accelerated shelf life testing method was analyzed.Then,in order to investigate the differences in the main chemical components affecting the flavor of the YYB at different oxidation stages.Gas chromatography-mass spectrometry and ultrahigh performance liquid chromatography-quadrupole time of flight mass spectrometry was combined with multivariate statistical analysis to construct a classification model.Finally,a YYB production plant was designed.An overview of the process and project investment was provided.The main research components and conclusions of this thesis are summarized as follows.(1)Introduced the background of the research and the significance of the selected project.According to the production requirements of the YYB,the composition and characteristics of YYB are outlined,and the oxidation mechanism of fat in YYB and the important factors affecting fat oxidation are analyzed.What’s more,(2)Explored the oxidative stability of YYB at different accelerated oxidation stages.YYB without nitrogen filling was stored for 16 days.The color of the YYB gradually deepened(turned red and yellow)during the 16 days of accelerated oxidation.At the same time,the content of linoleic acids was the highest among these fatty acids found in YYB,the content of unsaturated fatty acids showed a significant decrease but a slight increase in the saturated fatty acids.In addition,the peroxide value of YYB increased rapidly during the first 8 days,and then reached the maximum on day 14 and decreasing lastly,but the carbonyl value keeps increasing throughout.The induced oxidation time of YYB increased by a factor of about 2 according to the trend of change for every 10°C in temperature.There was also a highly significant negative correlation(p<0.01)with both the peroxide and carbonyl values,which means induced oxidation time is a rapid and accurate assessment of the oxidative stability of YYB.These oxidation indicators provide an integrated and comprehensive assessment of the changes in YYB quality during oxidative storage.(3)Gas chromatography-mass spectrometry was used to investigate the changes in the volatile compounds of the YYB during accelerated oxidation.Firstly,a total of50 volatile compounds were identified,mainly including 12 aldehydes and ketones,8alcohols,9 esters,18 hydrocarbons and 3 oxygenated compounds.The volatile components of the YYB samples were similar at different stages of accelerated oxidation,but there were significant differences in content.In addition,aldehydes and ketones and oxygenates accumulated during oxidation storage.But alcohols,esters and hydrocarbons decreased.The results of the multivariate statistical analysis showed significant differences among the nine groups of samples,which could be separated into pre-accelerated oxidation storage(0-8 days)and late-accelerated oxidation storage(10-16 days).Meanwhile,Esters and alkanes were the main odor contributors for the fresh samples.Hydrocarbons were the main odor contributors for the samples oxidized for 2 and 4 days.Aldehydes and ketones,were the main odor contributors for samples oxidized for more than 6 days.Finally,6 characteristic volatiles including 2-hexyl-1-decanol and 2-methylhexadecan-1-ol were selected to differentiate YYB samples oxidized for 0-16 days.Also,four characteristic volatiles,such as(E)-2-heptenal,were able to distinguish YYB in the pre-accelerated stage,and 13 characteristic volatiles,such as isophorone,were able to distinguish samples in the late-accelerated stage.These characteristic volatiles are key substances of sour taste formed during storage.(4)Ultrahigh performance liquid chromatography-quadrupole time of flight mass spectrometry was performed to explore the changes of non-volatile components during oxidation storage.The non-volatile components of YYB were also split nine groups of samples into the pre-oxidation period(0-8 days)and the post-oxidation period(10-16days).85 and 72 characteristic compounds were identified in positive and negative ion modes respectively.18 differential compounds were accurately identified,mainly including organic acids,amino acids and esters.These characteristic compounds were able to distinguish YYB samples at different oxidation storage stages.They are the key components in the production of sour taste during storage.(5)The production process of YYB in factory was designed to promote a deeply study of YYB.