Glycosidically bound aroma precursors in fruits: A comprehensive review

Odour-active compounds in liquid malt extracts for the baking industry

An odorant screening by gas chromatography–olfactometry (GC–O) and a crude aroma extract dilution analysis (AEDA) applied to the volatiles isolated from a light and a dark liquid malt extract (LME) by solvent extraction and solvent-assisted flavour evaporation (SAFE) identified 28 odorants. Fifteen major odorants were subsequently quantitated and odour activity values (OAVs) were calculated as ratio of the concentration to the respective odour threshold value (OTV). Important odorants in the light LME included 3-(methylsulfanyl)propanal (OAV 1500), (E)-β-damascenone (OAV 430), and 4-ethenyl-2-methoxyphenol (OAV 91). In the dark LME, sotolon (OAV 780), 3-(methylsulfanyl)propanal (OAV 550), (E)-β-damascenone (OAV 410), acetic acid (OAV 160), and maltol (OAV 120) were of particular importance. To get an insight into the changes during malt extract production, the quantitations were extended to the malt used as the starting material for both LMEs. Addition of a minor amount of water to malt before volatile extraction was shown to be effective to cover the free as well as the bound malt odorants. Results showed that some LME odorants originated from the starting material whereas others were formed during processing. Important process-induced LME odorants included (E)-β-damascenone and 4-ethenyl-2-methoxyphenol in the light LME as well as maltol, sotolon, (E)-β-damascenone, and 2-methoxyphenol in the dark LME. In summary, the odorant formation during LME production was shown to be more important than the transfer of odorants from the malt.

Optimizing extraction method of aroma compounds from grape pomace

Grape pomace is a major wine industry byproduct. Extraction of volatile compounds from grape pomace is rarely explored. A cost-effective method was developed in this study for aroma compounds extraction from grape pomace with the potential for industrial application. Based on the solvent extraction procedure, experimental factors including pretreatment, enzymatic hydrolysis time, solvent concentration and distillation time were investigated to optimize the extraction process. Volatile compounds of the pomace extract were analyzed using headspace solid-phase microextraction gas-chromatography mass spectrometry (HS-SPME-GC-MS) method. Results revealed that enzymatic hydrolysis was the optimal pretreatment method. A maximum extraction efficiency was achieved under 48 hr of enzymatic hydrolysis, 70% of ethanol concentration and 20 min of distillation. A total of 65 volatile compounds were identified in the extract, including 16 alcohols, 1 alkane, 1 aldehyde, 9 esters, 3 ketones, 4 phenols, 6 terpenes, and 1 furan, of which 15 volatiles were determined as odor-active compounds. This study developed a feasible extraction technique to recycle the underutilized byproducts from wine industry to produce aroma/flavor food additives. PRACTICAL APPLICATION: This study develops a cost-effective method for aroma compounds extraction from grape pomace with the potential for industrial application as food additives.