Study on the Quality Changes of Coffee Malt Premixed Powder Applied to Baking Products during Storage

In order to study the quality change of coffee malt premixed powder with the extension of storage period, the coffee malt premixed powder was stored at the environment where the temperature is 25 ℃ and 35 ℃, respectively, and the relative humidity is 50% respectively. Its moisture, fatty acid value and falling value were monitored during the whole storage period. The volatile compounds were separated and identified by solid phase microextraction accompanying gas chromatography-mass spectrometry during the whole storage period. The results demonstrated that with the extension of storage period, the overall moisture content shows a falling trend, while the fatty acid value and falling value show an overall rising trend. The higher the storage temperature, the more significant the change is 41 kinds of main volatile compounds of coffee malt ready mixed powder were identified. It mainly includes 13 kinds of aldehydes, 15 kinds of heterocycles, 7 kinds of esters, 4 kinds of alcohols and 2 kinds of ketones. Among them, the relative concentration of aldehydes (n-hexanal, nonanal, trans-2-nonenal) showed an increasing trend with the extension of storage period.