Abstract: Solid phase micro-extraction (SPME) and gas chromatography-mass spectrometry (GC-MS) were used to analyze the volatile flavor compounds of naturally fermented and artificially inoculated Chinese leaf mustard grown in Hunan province, China. The two samples were contrasted with respect to nitrite content, pH value and sensory quality. The results showed that the main volatile flavor compounds of naturally fermented and inoculated samples with temperature control, were similar, with esters being the most abundant constituents (over 40.02%). The volatile flavor composition of naturally fermented mustard at ambient temperature was significantly different from those of the former two samples, with the predominance of alcohols (only 5.51%). A total of 64 (11 classes) of volatile flavor compounds were identified in four fermented Chinese leaf mustard samples: A, inoculated with Lactobacillus plantarum and Pediococcu pentosaceus (21 volatile compounds including 7 esters belonging to 9 classes); B, inoculated with L. plantarum, P. pentosaceus and Leuconostoc mesenteroides (24 volatile compounds including 8 esters belonging to 10 classes); C, naturally fermented with temperature control (20 volatile compounds including 5 esters belonging to 9 classes; and D, naturally fermented at ambient temperature (32 volatile compounds including 7 alcohols and 6 esters belonging to 10 classes). The nitrite content and pH value of artificially inoculated Chinese leaf mustard were lower than those of natural fermentation, and the sensory scores of the samples from artificial inoculation and temperature-controlled natural fermentation were similar but higher than that of natural fermentation without temperature. Therefore, artificial inoculation can be useful to ensure the commerciality and safety of fermented Chinese leaf mustard and is promising for wide application.

Key words: natural fermentation, artificial inoculation, volatile flavor compounds, Chinese leaf mustard, nitrite