Studies On Relationship Between Quality Changes And Volatiles Of The Wheat During Storage

In this paper, headspace solid-phase micro-extraction (HS-SPME) together with gaschromatography and mass spectrum (GC-MS), and Electronic Nose technology,combining with conventional methods, were used to study the wheat quality and volatileschanges during storage. The results were showed as following:(1) Fatty acid values and falling number were increased with extend of storage timeand rising of temperature. Both of them had notable relevance to storage temperature, andextremely significant correlation with storage time（P≤0.01）. Taste grading marks hadnegative correlation with storage time. Moisture content had extremely significant positivecorrelation with falling number, so as to fatty acid values with falling number.(2) HS-SPME and GC-MS were used in determining wheat volatiles. The resultsshowed that the volatiles compositions were alcohols, aldehydes, ketones, hydrocarbons,as well as a small quantity of esters, organic acids, and heterocyclic compounds. Thecontents of1-hexanol,1-octanol and1-hexdeanol decreased during storage; proportions ofE-15-heptadecanal,2-nonenal and benzeneacetaldehyde increased in different storageconditions; total content of ketones increased too; percentages of primary hydrocarbonsrised, such as pentadecane, hexadecane and octadecane.(3) While used to detect wheat volatiles, Electronic Nose (E.N.) response values of15s-20s and40-45s were chosen as characteristic value using in principal componentanalysis (PCA) and linear discrimination analysis (LDA).LDA did better in distinguishingwheat of different storage times, while PCA was superior in discriminating wheat indifferent temperatures. Wheat could be sorted by gluten content, storage time andstorage temperature, and when the wheat samples were sorted definitely, E.N.anylasis could distinguish samples from each other better.(4)Analytical results of relationship between wheat volatiles and storage qualityshowed that there was good correlation between quality indicators and the relative contentof hexanol, octanol, benzaldehyde, pentadecane, hexadecane. The electronic nose responsevalue of different sensors and wheat quality indexes related to different extent, and sensor10has best correlation with wheat storage quality.