Identification and Distribution of New Impact Aldehydes in Toasted Oak Wood (Quercus petraea)

Distribution and Sensory Impact of (2E,4E,6Z)-nonatrienal and Trans-4,5-epoxy-(E)-2-decenal in Wines and Spirits

This study reports the distribution of (2E,4E,6Z)-nonatrienal (1) and trans-4,5-epoxy-(E)-2-decenal (2) in wines and spirits. We validated a quantification method using solid-phase extraction (SPE) and negative chemical ionization (NCI, NH3) gas chromatography-mass spectrometry (GC-MS) analysis. Both were identified for the first time in wines and spirits from different grape varieties and raw materials. Their olfactory detection thresholds (ODTs) were 16 and 60 ng/L, respectively. Analysis of 66 wines showed that the highest levels of (1) (441.3 ng/L) and (2) (386.5 ng/L) were found in red and white wines, respectively. At these levels, they modify the balance of the fruity expression of red (fresh to cooked fruits) and white (vegetal/green hazelnut nuance) wines. Similar quantitative and sensory analyses were conducted in spirits. With ODT estimated at 500 and 400 ng/L and concentrations ranging from trace amounts to 1.1 and 2.4 μg/L respectively, (1) and (2) can contribute directly to the aroma of spirits.

Optimizing the identification of thiols in red wines using new oak-wood accelerated reductive treatment

This study proposes a new method for identifying thiols in red wines by mimicking specific chemical mechanisms that occur during bottle-aging. It involves the reaction of oak-wood extracts with hydrogen sulfide and the reduction of disulfides with DIBAL. After optimization of the reaction conditions, the aroma of fresh oak wood turned into intense "meaty" nuances reminiscent of the aging bouquet of red wines. Samples were analyzed by gas chromatography coupled with olfactometry (GC-O) and coupled with a pulsed flame photometric detector. This resulted in the identification of six odorant zones with meaty descriptors associated with sulfur compounds. One of the odorant zones was identified as 2-methoxybenzenethiol by using heart-cutting multidimensional GC coupled with olfactometry and time of flight mass spectrometer. Its identification in aged red wines was confirmed by GC coupled with tandem mass spectrometry analyses. Five other thiols associated with oak-wood precursors were also identified in red wines.

Characterization of Solar Radiation-Induced Degradation Products of the Plant Sunscreen Sinapoyl Malate

Agricultural activities at lower temperatures lead to lower yields due to reduced plant growth. Applying photomolecular heater agrochemicals could boost yields under these conditions, but UV-induced degradation of these compounds needs to be assessed. In this study, we employ liquid chromatography-mass spectrometry (LC-MS) coupled with infrared ion spectroscopy (IRIS) to detect and identify the degradation products generated upon simulated solar irradiation of sinapoyl malate, a proposed photomolecular heater/UV filter compound. All major irradiation-induced degradation products are identified in terms of their full molecular structure by comparing the IRIS spectra obtained after LC fractionation and mass isolation with reference IR spectra obtained from quantum-chemical calculations. In cases where physical standards are available, a direct experimental-to-experimental comparison is possible for definitive structure identification. We find that the major degradation products originate from trans-to-cis isomerization, ester cleavage, and esterification reactions of sinapoyl malate. Preliminary in silico toxicity investigations using the VEGAHUB platform suggest no significant concerns for these degradation products' human and environmental safety. The identification workflow presented here can analogously be applied to break down products from other agrochemical compounds. As the method records IR spectra with the sensitivity of LC-MS, application to agricultural samples, e.g., from field trials, is foreseen.

Distilled beverage aging: A review on aroma characteristics, maturation mechanisms, and artificial aging techniques

The market value of distilled beverage relies on its quality with a major contribution of distinctive and fascinating aromas. The aroma of distilled beverage is built on the basis of chemical components and can be modified through a series of physical and chemical processes such as aging. Revealing the hidden knowledge behind the evolution of numerous chemical components during these physicochemical processes in distilled beverages is not only significant but also challenging due to its complex system. In this review, the trends in the changes of associated aroma compounds over aging are proposed on the basis of understanding the relationship between chemical components and aroma profiles of numerous typical distilled beverages. The different aging systems, both classical platforms from Eastern countries (pottery jars) to Western countries (wood barrels), and modern platforms such as artificial aging technologies are outlined and compared with their respective applications. Optimizing aging processes is a challenging but imperative step, which warrants further fundamental knowledge from targeting aging-related molecules to the exploration of multitude physicochemical reaction mechanisms that occur during this process, such as the formation of potent odorant compounds in specific containers and environments, as well as mass transfer processes between solid and liquid interfaces. Understanding these maturation mechanisms of distilled beverages expressed by chemosensory signature holds promise for major improvements in future aging technologies that can efficiently yield stable and high-quality products.