Changes of microbial diversity and volatile compounds in edible and deteriorated Qingke barley fresh noodles stored at 25 °C

Microbial diversity and volatile compounds in Qingke barley fresh noodles (QBFN) with different storage time at 25 +/- 1 degrees C were investigated. The results showed thatPseudomonas,Pantoea,ErwiniaandAlternaria,Pyrenophora,Penicilliumwere the dominant microorganisms in edible QBFN (stored for 0 and 12 h), whilePantoea,Erwinia,BacillusandPenicillium,Aspergilluswere the dominant spoilage microorganisms in deteriorated QBFN (stored for 18 h). The edible QBFN have high concentration of aldehydes (61.27 mu g kg(-1)), furan and pyrazines (60.87 mu g kg(-1)), alcohols (49.74 mu g kg(-1)) and ketones (29.74 mu g kg(-1)) that give basic flavours to the QBFN. As storage time increased, the concentrations of above volatile compounds decreased, and new esters and sulphuric compounds which gave unpleasant odours to the QBFN appeared. Multivariate data analysis methods showed that 2-pentyl-furan, hexanal, 5-Ethylcyclopent-1-enecarboxaldehy, cyclohexanol and methyl allyl sulphide, ethyl isovalerate were the main volatile compounds that make a difference in flavour between the edible and deteriorated QBFN.