Determination of potential off-flavour in yeast extract

Effect of static‐state fermentation on volatile composition in rapeseed meal

“…The concentration decreased from 4.85 to 2.77 mg kg −1 as the fermentation time increased (Table ). However, hydrocarbons usually have high threshold values and so would contribute little to the flavor of RSM and FRSM . The levels of aldehydes, which have a strong fat aroma, increased rapidly at first and then decreased after 1 day of fermentation (Fig.…”

Characterization of key aroma‐active compounds in four commercial egg flavor Sachimas with differing egg content

“…In four samples, the number of aroma‐active compounds in Premium, Classical, Whole egg, and Egg yolk was included 22, 21, 21, and 19, respectively. Considering the FD factors listed in Table , the following compounds had higher FD values and may therefore have made a greater contribution to the total aroma profile of the Sachima samples than other compounds with lower FD values (Zhang et al, ): 3‐methylbutanal (FD = 81, malty); 3‐(methylthio)propanal (FD = 81, cooked potato); n‐propylacetate (FD = 81, cheesy); 2,5‐dimethylpyrazine (FD = 81, roasted nut), 2‐ethylpyrazine (FD = 81, peanut butter), 2‐methylbutanal (FD = 27, cocoa, almond), hexanal (FD = 27, grassy), 1‐octen‐3‐one (FD = 27, mushroom), 2,3‐dimethylpyrazine (FD = 27, nutty), 2‐pentylfuran (FD = 3, green bean), nonanal (FD = 9, green), furfural (FD = 3, bread), benzaldehyde (FD = 3, almond), and 2‐furanmethanol (FD = 3, burnt). If compared with four samples, interestingly, the aroma‐active compounds with the highest FD factor including 3‐methylbutanal (FD = 81, malty); 3‐(methylthio)propanal (FD = 81, cooked potato); n‐propylacetate (FD = 81, cheesy); 2,5‐dimethylpyrazine (FD = 81, roasted nut), 2‐ethylpyrazine (FD = 81, peanut butter) were most detected in Premium samples.…”

“…The reason for these unexpected results most likely because the odor threshold of an aroma compound was not necessarily same in different media (Gemert, ). What's more, when using the OAV approach, it is assumed that the relationship between the aroma intensity of each compound and its concentration was linear (Zhang et al, ). However, the relationship between the log concentration of an aroma compound and the resulting potency of the aroma does not appear to be linear but, instead, is an S‐shaped curve, in which the psychometric functions of each flavor compound could not be ignored (Pang et al, ).…”

“…where N represented the number of carbon atoms with peaks in front of the identified compound, n represented the numerical difference between the upper and lower n‐alkanes in gas chromatography, and the variables t Ra , t RN , t R ( N + n ) denoted the retention time of the identified compounds and the upper alkane and lower alkanes, respectively. The final two methods of qualitative analysis that were conducted included odor descriptions (O) by comparison with reference compounds (Acree & Arn, ) and standard (STD) substances verification (Zhang, Song, Li, Yao, & Xiong, ).…”

“…Two quantitative methods of analysis were used: A semi‐quantitative GC‐MS method in Scan mode for the evaluation of total aroma compounds, in order to make a rough distinction among the four Sachima samples; An external standard selected ion monitoring (SIM) GC‐MS method for quantification of the key aroma‐active compounds in each of the four Sachima samples (Zhang et al, ). In the Scan mode, all ions are scanned, whereas in SIM mode, several ions are monitored during data acquisition (Tan et al, ).…”