BACKGROUND: Aroma-active compounds and non-volatile substances determine the characteristic aroma and taste of yeast extract (YE). Changes in the characteristic aroma and taste of YE due to thermal reaction are rarely studied, and the relationship between aroma-active compounds and non-volatile compounds is not yet clear. RESULTS: Non-volatile compounds identified by HPLC and LC/MS/MSwere reduced by a rise in temperature, except for some amino acids. Peptides underwent degradation. In addition, a further rise in temperature above 120 ∘ C resulted in a bitter and sour taste. Furans, pyrazines, thiophenes, thiazoles and some branched chain sulfur compounds were derived from GC/O/MS (SPME and SAFE). Sensory results revealed that the concentration of volatile compounds increased with an increase in temperature. The overall aroma profiles of YE at 25, 100 and 110 ∘ C were buttery, green, nutty and meaty, while YE at 140 ∘ C had a strong sour and sulfur odour. CONCLUSION:The non-volatile compounds of YE were reduced and different volatile compounds were produced under different thermal treatments. There was a negative correlation between these two types of compounds. The different taste sensors and all precursors were correlated with each other. There are significant relationships between different odorants and aroma-active compounds of YE after thermal treatment. Industry the GC/MS total ion chromatograph (TIC) was performed following the NIST 05 mass spectra libraries. The odour descriptions, RI values and linear retention indices (LRIs) on DB-5MS and DB-WAX columns were observed to be similar to those reported J Sci Food Agric 2018; 98: 3774-3783 /jsfa ± 6.75b 232.58 ± 106.02a 338.07 ± 79.24a J Sci Food Agric 2018; 98: 3774-3783

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BACKGROUND Many studies have been performed over the past four decades to identify and quantify the odor‐active key volatiles in yeast extract (YE) but knowledge of the nonvolatile taste compounds is still rather fragmentary. In particular, research on bitter peptides with various structures during the thermal treatment of YE is still scarce. RESULTS Compounds imparting a bitter taste to thermally treated YE were investigated using sensory‐guided fractionation. This research found that when the treatment temperature reached 130 °C, bitter peptides were generated. Sensory evaluation of the purified, synthesized peptides revealed that four of these peptides showed a pronounced bitter taste with a taste dilution (TD) factor from 5 to 9. Guidance is provided for the production of bitter peptides in the flavor industry. CONCLUSION Based on results from previous work on umami peptides, and this study, keeping the thermal reaction temperature under 120 °C could maximize the umami flavor and control bitterness so that it remains in an acceptable range. © 2019 Society of Chemical Industry