| In order to improve the storage quality and utilization rate of raw materials of highland barley,and to understand its quality changes during storage.Focusing on the storage of highland barley,this project carried out storage experiments under the conditions of normal temperature(average 20℃ RH75%),high temperature and high humidity(30℃ RH75%,40℃ RH75%),tested the changes of physicochemical,biochemical,color and volatile substances during the storage of highland barley,and carried out lipid proteomics analysis to explore the quality change law of highland barley during the whole storage process.(1)19 amino acids and 25 fatty acids were detected in highland barley.Through the storage of newly harvested highland barley,it was found that temperature would affect the storage quality of highland barley grains and highland barley powder,and the storage conditions of high temperature and high humidity would accelerate the quality change of highland barley.During the whole storage process,the moisture content of barley grains and barley powder fluctuated in the range of 5% ～ 23% under different storage conditions,and the fatty acid value changed gradually,and the malondialdehyde content also changed gradually.With the extension of storage time,the water-soluble protein concentration of highland barley grains and highland barley powder fluctuated in the range of 1.43 mg/g ～ 1.81 mg/g under different storage conditions.During the whole storage process,the activities of lipoxygenase(LOX)and catalase(CAT)increased first and then decreased,and the variation ranges were different under different storage conditions.The changes of LPS activity in highland barley grain and highland barley powder showed a downward trend during storage.(2)The study on the color changes of barley grains and barley powder during storage showed that low temperature played an important role in delaying the color changes of barley grains and barley powder.At the same time,the volatile components of highland barley granules and highland barley powder during storage were analyzed,and 32 volatile components were identified in highland barley granules.Among them,five kinds of aldehydes were detected,with an average percentage of 47.45%.With the storage time going on,the content of esters decreased first and then increased,and the esters had fruit fragrance,which made the overall flavor sweet.Secondly,the content of aldehydes was relatively high,with an average percentage of 21.58%.With the storage time,the content of aldehydes increased first and then decreased.The number of phenols is the least,with an average percentage of 2.73%;The percentage of other ketones,alcohols and hydrocarbons is above 7.90%.Hydrocarbons account for a large contribution in highland barley flour,with an average percentage of 43.30%.The sensory quality of highland barley granules and highland barley powder during storage was studied to provide a new evaluation index for detecting the freshness of highland barley.During storage,45 components were detected in highland barley powder,which was much higher than the number of volatile substances detected in highland barley grains.Among them,the number of hydrocarbons was the largest,with 19 species detected,followed by 7 aldehydes,7 alcohols,5 esters,3 ketones,1 phenol and3 others.(3)PCA analysis was used to study the differences of samples of highland barley grain and highland barley powder under different storage conditions.As a whole,it can be seen that the difference between highland barley grain and highland barley powder is the largest when stored at 40℃ for 28 days.Further OPLS-DA analysis of metabolism.The screening results showed that when barley grains and barley powder were stored at 40℃ and RH 75% for 28 days,the number of differential metabolites screened was the highest,with 95,of which 89 were up-regulated and 6 were down-regulated.When barley grains and barley powder were stored for 0 days,the number of differential metabolites screened out was the least,with 46,of which 39 were up-regulated and 7 were down-regulated.The metabolic pathways involved in lipid metabolites are mainly tumor choline metabolism,α-linolenic acid metabolism,arachidonic acid metabolism,glycerophosphate metabolism,linoleic acid metabolism,ephedrine signaling pathway,phospholipase D signaling pathway,tumor choline metabolism,glyceride metabolism,gonadotropin-releasing hormone signaling pathway,FcγR-mediated phagocytosis pathway,endogenous jute signaling pathway,tumor choline metabolism,glycosyl phosphatidylinositol(GPI)-anchor biosynthesis,and so on. |
