Characteristic flavor fingerprint disclosure of dzo beef in Tibet by applying SAFE-GC-O-MS and HS-GC-IMS technology.

To understand the overall flavor of the dzo beef, fatty acids, volatile compounds and aroma profiles of dzo beef samples (raw beef (RB), broth (BT) and cooked beef (CB)) were investigated by head-space-gas chromatography-ion mobility spectrometry (HS-GC-IMS) and gas chromatography-mass spectrometry (GC-MS). The fatty acid analysis showed a decrease in the ratio of polyunsaturated fatty acids, such as linoleic acid, which decreased from 2.60 % in RB to 0.51 % in CB. The principal component analysis (PCA) showed that HS-GC-IMS was able to distinguish different samples. A total of 19 characteristic compounds with odor activity value (OAV) > 1 were identified by gas chromatography-olfactometry (GC-O). Fruity, caramellic, fatty and fermented attributes were enhanced after stewing. Butyric acid and 4-methylphenol were responsible for the stronger off-odor in RB. 3-Hydroxy-2-butanone and 2,5-dimethyl-4-hydroxy-3(2H)-furanone with buttery and caramellic attributes were dominated in BT, while (E)-2-nonenal, (E,E)-2,4-decadienal and (E,E)-2,4-nonadienal prominently conferred fatty attribute on CB. Furthermore, anethole with anisic aroma was first identified in beef, which may be one of the typical chemical markers that distinguish dzo beef from other varieties.

Variation of Volatile Compounds and Corresponding Aroma Profiles in Chinese Steamed Bread by Various Yeast Species Fermented at Different Times.

To control the fermentation process of yeast-Chinese steamed bread (CSB), the volatile compounds and odor profiles of yeast-CSBs during fermentation were comprehensively investigated by sensory evaluation, gas chromatography-mass spectrometry, gas chromatography-olfactometry (GC-O), and odor activity value (OAV). Eight sensory attributes were established, and quantitative descriptive analysis results showed that CF1303-CSB had intense sweet and sweet aftertaste attributes, CF1318-CSB was characterized by milky, wheaty, and yeasty attributes, while CL10138-CSB presented distinct sour, winy, and floury attributes. A total of 41 key aroma-active compounds were detected, and phenylethyl alcohol was the most potent aroma compound with a flavor dilution (FD) of 1024. CF1303-CSB, CF1318-CSB, and CL10138-CSB contained 24, 22, and 21 key aroma compounds, respectively, based on the OAV. These key aroma compounds can be used as the potential markers to monitor the yeast-CSBs during the fermentation process. Five compounds, including ß-myrcene, 2-phenoxyethanol, methyl cinnamate, guaiacol, and o-cresol, were first identified in CSB. These results provide theoretical basis for processing and quality control of yeast-CSBs.