Determination of potential off-flavour in yeast extract

Yeast extracts is a kind of food ingredient for enhancing flavor, but some yeast extract samples had yeasty odour (off-flavour). The aim of this study was to detect key aroma compounds leading to the yeasty odour. Volatile compounds of 3 yeast extracts (with yeasty odour), FA and FB, LC were extracted by solid phase micro-extraction (SPME) and solvent assisted flavour evaporation (SAFE) respectively, and analysed by gas chromatography-olfactrometry-mass spectrometry (GC-O-MS) and aroma extract dilution analysis (AEDA) techniques. Thirty aroma-active compounds were detected, among them 4methylphenol, 3-methylpyridine, 3-methylbutanoic acid, propanoic acid with high FD factors (FD = 125, 125, 625, 125, >= 25), were identified as the key off-flavours responsible for yeasty and their accurate quantification were done by external standard method in SIM mode. Calculation of the OAVs revealed 3-methylbutanoic acid, 3-methylpyridine, 4-methylphenol as the key odourants in the extract. For the verification of analyzed off-flavours, sensory evaluations of aroma model were conducted by eight panelists, and the result showed that aroma recombinate had the yeasty odour profile similar with the original yeast extracts. The methods were successful for the detection of off-flavors in yeast extract and the four off compounds analyzed were mainly responsible for the yeasty flavour. (C) 2017 Elsevier Ltd. All rights reserved.