Characterization of odor components of Pixian Douban (broad bean paste) by aroma extract dilute analysis and odor activity values

Abstract

The odor-active compounds of Pixian Douban (PXDB) were identified by means of gas chromatography-olfactometry (GC-O) coupled with mass spectrometry (MS), and then the key odor components were figured out by odor activity values (OAVs) and aroma extract dilution analysis (AEDA) using three different methods. The 21 odor active areas were detected with flavor dilution (FD) factor ranging from 2 to 16, with 3-(methylthio) propionaldehyde, 2, 5-dimethyl pyrazine, 4-ethyl-2-methoxyphenol, and 2-ethylphenol yielding the highest FD factors. These odorants were then quantitated by application of external standard under selected ion monitoring (SIM) mode of MS, and their OAVs were calculated based on the odor thresholds. The highest OAV was obtained for 3-methylbutanal (malty, 614.89), followed by phenylacetaldehyde (honey-like, sweet, 94.34), four compounds obtained OAVs ≥10, and other eight compounds obtained OAVs between 1 and 10. All of them likely contributed to the aroma of PXDB. A reconstitution model containing 14 odorants (OAVs ≥1& FD>5) was able to mimic the aroma style of the original PXDB. In addition, the application of omission test was used to investigate the effects of the key odor compounds on the whole odor profile of PXDB, and 11 odorants detected were significantly different among the samples.

Dynamics and correlation of microbial community and flavor in Pixian Douban fermented with closed process of constant temperature

“…Both components play key roles in the unique flavor of PXDB for the two fermentation processes. Besides, 12 of the other 98 aroma components sharing the two fermentation processes coincided with the characteristic aroma components of PXDB reported in the literature, 14,15,29 namely linalool, phenylethanol, furfural, 3‐(methylthio)propionaldehyde, phenylacetaldehyde, 2‐methylbutyric acid, ethyl 2‐methylbutrate, ethyl caprylate, methyl palmitate, ethyl isovalerate, 4‐ethylphenol and 4‐ethyl‐2‐methoxyphenol. Furthermore, as common components in soy sauce and other fermented bean foods, 30–33 the relative contents of phenylacetaldehyde, 4‐ethyl‐2‐methoxyphenol, 4‐ethylphenol and phenylethanol were higher than those of the other eight components in this study.…”

“…Like other fermented foods, the aroma components and formation mechanisms of PXDB are very complicated, and are affected by many factors such as temperature, water, air and microorganisms; thus many studies concerning the aroma of PXDB have been conducted in recent years 14,29 . In this work, although the components of the characteristic aroma formed in the CFCT were almost the same as in traditional fermentation, more new components were easily produced under the influence of multiple factors, as found in the first month of traditional fermentation.…”

“…The flavor components analyzed in Fig. 8 included 12 aroma compounds identified as the key volatile flavors of PXDB in the literature, 3,14,15,29 six organic acids and 17 free amino acids. As presented in Fig.…”

Characterization of volatile compounds of Pixian Douban fermented in closed system of gradient steady‐state temperature field

“…Therefore, the new process should be developed based on the study of traditional fermentation process to obtain high‐quality product with good aroma. In the literatures, many studies about the volatile compositions of PXDB have been conducted, and many valuable results were obtained (Li et al., 2016, 2018, 2019; Lin et al., 2019). In Lu's study, 22 key volatile compounds were identified in PXDB fermented with traditional process (Lu et al., 2019).…”

“…The microbial communities, flavors, and their relationships in PXDB were studied in Liu's study, which revealed that the flavor compounds would accumulate significantly with the prolonging of the fermentation period, especially for umami‐taste amino acids, organic acids, and volatile compounds (Liu et al., 2020). In Lin's study, 21 aroma active compounds were detected with flavor dilution factor ranging from 2 to 16 in PXDB (Lin et al., 2019). Those researches were benefit of revealing the aroma of the traditional fermentation products and provided the foundation for the studies of new process.…”