Sam Al-Dalali,Fuping Zheng,Baoguo Sun,Chenxi Zhou,Ming Li,Feng Chen
Effects of different brewing processes, such as the solarization process (i.e. with or without), selection of different types of rice as a raw material (i.e. normal or sticky rice), and addition of flavoring materials (i.e. presence or absence of spices or sugar), on the aroma profiles of three types of Chinese vinegars were investigated. These three vinegars were the Longmen aromatic sweet rice vinegar (LASRV), Longmen aromatic rice vinegar (LARV), and Longmen rice vinegar (LRV). Headspace solid-phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS) and HS-SPME-aroma extract dilution analysis combined with gas chromatography-olfactometry (HS-SPME-AEDA-GC-O) were used to identify and quantify the volatile compounds, as well as the aroma-active compounds in the Longmen vinegars. Among the total of 68 volatile compounds that were identified, 49 were confirmed by their corresponding chemical standards. The results showed that the LASRV sample contained higher concentrations of acids, alcohols, esters, sulfides, acetal, and aromatic hydrocarbons because of effects of the solarization process and the presence of added sugar. The LARV sample was found to contain more aldehydes, pyrazines, ketones, phenols, lactone, and oxazoles, which might be contributed by the solarization process, as well as the addition of spices.
High-performance liquid chromatography (HPLC), headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC–MS) and ultra-high performance liquid chromatography–Q-Exactive HF-X mass spectrometer (UHPLC–Q-Exactive HF/MS) were carried out to reveal dynamic changes of volatile and non-volatile compounds during the withering process of black tea. A total of 118 volatile organic compounds (VOCs) and 648 metabolites were identified in fresh and withered tea-leaves, respectively. Among them, 47 VOCs (OAV > 1.0) for the aroma formation, and 46 characteristic metabolites (VIP > 1.50, p < 0.01) selected through orthonormal partial least squares-discriminant analysis, indicated the withering contribution during black tea processing. Overall, the withering promoted alcohols, aldehydes, phenols, heterocyclic oxygen, hydrocarbons and halogenated hydrocarbons through relevant hydrolyzation, decomposition, terpene synthesis, and O -methylation. The hydrolyzation, O -methylation, condensation and N -acylation of kaempferol glycosides, quercetin glycosides, ester catechins, and gallic acid generated the accumulation of methoxyl flavonoids and flavonoid glucosides, dihydrokaempferol, syringic acid, theaflavins, and N -acylated amino acids, respectively.
危险品化学品经营许可证（带存储）