Identification of odorous compounds in oak wood using odor extract dilution analysis and two-dimensional gas chromatography-mass spectrometry/olfactometry

Abstract

Over the centuries, oak wood has been used in the maturation process of alcoholic beverages imparting aroma and flavor notes. Whereas several studies have dealt with the impact of oak wood on the chemical composition of, for example, wine aroma, only limited information is available on the odorant composition of unmodified and raw oak wood itself. To close this gap, a combination of human sensory and chemo-analytical techniques was applied for the elucidation of the chemical composition of oak odor, comprising extraction of the volatile fraction of oak wood by means of solvent-assisted flavor evaporation (SAFE) and subsequent mild concentration of the distillate. Odor extract dilution analysis (OEDA), which is based on gas chromatography-olfactometry (GC-O), was then applied for the targeted characterization of the odor-active compounds. Overall, a total of 97 odorants was identified via gas chromatography-mass spectrometry/olfactometry (GC-MS/O) and heart-cut two-dimensional gas chromatography-mass spectrometry/olfactometry (2D-GC-MS/O). The majority of these odorants comprised a series of terpenes, mainly mono- and sesquiterpenes, aldehydes, acids, and lactones, as well as a number of odorants containing a phenolic core moiety. Several odorants are reported here for the first time as volatile organic compounds in oak wood. Identification of the molecular composition of oak wood odor helps to establish a better understanding of the distinctive smell of oak wood, and offers the basis for unveiling its potential effects on humans when being exposed to oak wood smell in daily life. Graphical abstract ᅟ.

Removal of wood extractives as pulp (pre-)treatment: a technological review

“…Besides the negative impact on color and bleachability, wood extractives are also responsible for the odor of the pulp [86]. Ghadiriasli et al [87] identified various volatile organic compounds (VOC), including terpenes https://doi.org/10.1007/s42452-021-04873-1 and degradation products from fatty acids and lignin, as odor-active compounds in oak wood, while Schreiner et al [88] stated more precisely that fatty acid degradation products represent about two third of all the odoractive compounds in pine wood. Among all fatty acid degradation products, aldehydes play an essential role as odor-active compounds because their odor threshold is very low, and their smell is generally considered highly unpleasant [12,89].…”

Effect of lacquer decoration on VOCs and odor release from P. neurantha (Hemsl.) Gamble

“…in Germany by gas chromatography-olfactometry (GC-O) and aromatic extract dilution analysis, identifying 44 types of odorous compounds. Ghadiriasli et al 14 found that the odor of oak wood mainly came from fatty acid degradation products, terpenoids, and lignin degradation based on GC-O and odor extraction dilution analysis technology. It was found that most odor components of oak were composed of a series of terpenoids, mainly monoterpenes and sesquiterpenes, aldehydes, acids and lactones, and some polyphenols containing phenolic core components.…”

The Blossoming of Technology for the Analysis of Complex Aroma Bouquets—A Review on Flavour and Odorant Multidimensional and Comprehensive Gas Chromatography Applications

“…Smaller amounts of inorganic compounds and extractable substances, such as proteins, amino acids, fatty acids, terpenes, resin, acids, steroids, phenols, aldehydes, ketones, lactones and others are also present; it is in this group that we find the aroma compounds. Although there are many studies investigating the volatile composition of woods, few works concentrate on odour-active components [117,118,119].…”

“…Schreiner et al [117,120] and Ghadiriasli et al [118], dedicated their studies to the identification of aromas in cedar incense ( Calocedrus decurrens (Torr.) Florin), Scots pine ( Pinus sylvestris L.) and oak wood ( Quercus frainetto ), respectively.…”