Simultaneous Analysis of Organic Acids, Glycerol and Phenolic Acids in Wines Using Gas Chromatography-Mass Spectrometry

Fermented beverages, particularly wines, exhibit variable concentrations of organic and phenolic acids, posing challenges in their accurate determination. Traditionally, enzymatic methods or chromatographic analyses, mainly high-performance liquid chromatography (HPLC), have been employed to quantify these compounds individually in the grape must or wine. However, chromatographic analyses face limitations due to the high sugar content in the grape must. Meanwhile, phenolic acids, found in higher quantities in red wines than in white wines, are typically analyzed using HPLC. This study presents a novel method for the quantification of organic acids (OAs), glycerol, and phenolic acids in grape musts and wines. The approach involves liquid-liquid extraction with ethyl acetate, followed by sample derivatization and analysis using gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) detection mode. The results indicated successful detection and quantification of all analyzed compounds without the need for sample dilution. However, our results showed that the method of adding external standards was more suitable for quantifying wine compounds, owing to the matrix effect. Furthermore, this method is promising for quantifying other metabolites present in wines, depending on their extractability with ethyl acetate. Fermented beverages, particularly wines, exhibit variable concentrations of organic and phenolic acids, posing challenges in their accurate determination. Traditionally, enzymatic methods or chromatographic analyses, mainly high-performance liquid chromatography (HPLC), have been employed to quantify these compounds individually in the grape must or wine. The approach of this proposed method involves (i) methoximation of wine compounds in a basic medium, (ii) acidification with HCl, (iii) liquid-liquid extraction with ethyl acetate, and (iv) silyl derivatization to analyze samples with gas chromatography-mass spectrometry (GC-MS) in ion monitoring detection mode (SIM). The results indicated successful detection and quantification of all analyzed compounds without the need for sample dilution. However, our results showed that the method of adding external standards was more suitable for quantifying wine compounds, owing to the matrix effect. Furthermore, this method is promising for quantifying other metabolites present in wines, depending on their extractability with ethyl acetate. In other words, the proposed method may be suitable for profiling (targeted) or fingerprinting (untargeted) strategies to quantify wine metabolites or to classify wines according to the type of winemaking process, grape, or fermentation.

Phytochemical Profile of Trigonella caerulea (Blue Fenugreek) Herb and Quantification of Aroma-Determining Constituents

The herb of Trigonella caerulea (Fabaceae), commonly known as blue fenugreek, is used for the production of traditional cheese and bread varieties in the Alpine region. Despite its frequent consumption, only one study so far has focused on the constituent pattern of blue fenugreek, revealing qualitative information on some flavor-determining constituents. However, with regard to the volatile constituents present in the herb, the applied methods were insufficient and did not take relevant terpenoids into account. In the present study, we analyzed the phytochemical composition of T. caerulea herb applying a set of analytical methods, such as headspace-GC, GC-MS, LC-MS, and NMR spectroscopy. We thus determined the most dominant primary and specialized metabolites and assessed the fatty acid profile as well as the amounts of taste-relevant α-keto acids. In addition, eleven volatiles were quantified, of which tiglic aldehyde, phenylacetaldehyde, methyl benzoate, n-hexanal, and trans-menthone were identified as most significantly contributing to the aroma of blue fenugreek. Moreover, pinitol was found accumulated in the herb, whereas preparative works led to the isolation of six flavonol glycosides. Hence, our study shows a detailed analysis of the phytochemical profile of blue fenugreek and provides an explanation for its characteristic aroma and its health-beneficial effects.

Promotion of glyoxylic acid penetration into human hair by glycolic acid

OBJECTIVE

Glyoxylic acid (GA) is widely used as a straight perming agent for hair care products, however, advanced GA penetration-enhancing agents are desired due to the peculiar odour and hair colour fading caused by the continuous use of GA products. Hence, it is important to develop a penetration-enhancing agent that helps minimize the GA concentration. We have found that the combined use of GA and glycolic acid (GCA) has a strong hair straightening effect.

METHODS

Straightening hair test was carried out to the evaluation of the effect of additives. Liquid chromatography-mass spectrometry (LC/MS) was performed to quantify the GA penetration amount into human hair. Attenuated total reflection (ATR) Fourier transform-infrared spectroscopy (FT-IR) and FT-IR microscope were implemented to estimate the localization of GA in the hair.

RESULTS

Straightening hair tests indicated that the hair straightening effect by GA was enhanced by the presence of GCA. LC/MS results showed that the addition of GCA enhanced the amount of GA that penetrated human hair by about four times. ATR FT-IR and FT-IR microscope measurements indicated that GA was localized more in the innermost region of hair (medulla) than the cortex and cuticle. The GA accumulated in the medulla disappeared after a hair straightener treatment at 180°C due to the chemical reaction.

CONCLUSIONS

The GA penetration-enhancing effect of GCA is worth investigating to reduce the GA concentration in products for more comfortable use.

Aqueous Photochemistry of 2-Oxocarboxylic Acids: Evidence, Mechanisms, and Atmospheric Impact

Atmospheric organic aerosols play a major role in climate, demanding a better understanding of their formation mechanisms by contributing multiphase chemical reactions with the participation of water. The sunlight driven aqueous photochemistry of small 2-oxocarboxylic acids is a potential major source of organic aerosol, which prompted the investigations into the mechanisms of glyoxylic acid and pyruvic acid photochemistry reviewed here. While 2-oxocarboxylic acids can be contained or directly created in the particles, the majorities of these abundant and available molecules are in the gas phase and must first undergo the surface uptake process to react in, and on the surface, of aqueous particles. Thus, the work also reviews the acid-base reaction that occurs when gaseous pyruvic acid meets the interface of aqueous microdroplets, which is contrasted with the same process for acetic acid. This work classifies relevant information needed to understand the photochemistry of aqueous pyruvic acid and glyoxylic acid and motivates future studies based on reports that use novel strategies and methodologies to advance this field.

Beyond Ethylene: New Insights Regarding the Role of Alternative Oxidase in the Respiratory Climacteric

Climacteric fruits are characterized by a dramatic increase in autocatalytic ethylene production that is accompanied by a spike in respiration at the onset of ripening. The change in the mode of ethylene production from autoinhibitory to autostimulatory is known as the System 1 (S1) to System 2 (S2) transition. Existing physiological models explain the basic and overarching genetic, hormonal, and transcriptional regulatory mechanisms governing the S1 to S2 transition of climacteric fruit. However, the links between ethylene and respiration, the two main factors that characterize the respiratory climacteric, have not been examined in detail at the molecular level. Results of recent studies indicate that the alternative oxidase (AOX) respiratory pathway may play an essential role in mediating cross-talk between ethylene response, carbon metabolism, ATP production, and ROS signaling during climacteric ripening. New genomic, metabolic, and epigenetic information sheds light on the interconnectedness of ripening metabolic pathways, necessitating an expansion of the current, ethylene-centric physiological models. Understanding points at which ripening responses can be manipulated may reveal key, species- and cultivar-specific targets for regulation of ripening, enabling superior strategies for reducing postharvest wastage.

Impact of Fluorescent Lighting on Oxidation of Model Wine Solutions Containing Organic Acids and Iron

Previous studies have provided evidence that light exposure can increase oxygen consumption in wine and that the photodegradation of iron(III) tartrate could contribute to this process. In the present study, model wine solutions containing iron(III) and various organic acids, either alone or combined, were stored in sealed clear glass wine bottles and exposed to light from fluorescent lamps. Dissolved oxygen was monitored, and afterward the organic acid degradation products were determined and the capacity of the solutions to bind sulfur dioxide, the main wine preservative, was assessed. In the dark controls, little or no dissolved oxygen was consumed and the organic acids were stable. In the irradiated solutions, dissolved oxygen was consumed at a rate that was dependent on the specific organic acid present, and the latter were oxidized to various carbonyl compounds. For the solutions containing tartaric acid, malic acid, and/or citric acid, irradiation increased their sulfur dioxide-binding capacity.

Formaldehyde replacement with glyoxylic acid in semipermanent hair straightening: a new and multidisciplinary investigation

OBJECTIVE

Formaldehyde is an effective and popular semipermanent hair straightener, but the severe consequences for human health due to its toxicity have prompted the search for safer alternatives. Different carbonyl compounds, including glyoxylic acid, have recently been proposed as promising candidates. Despite the interest in this topic, there is a lack of information about the interactions between hair keratin and straightener agents. This study addresses this issue to gain new insights useful in the development of new products for safe, semipermanent hair deformation.

METHODS

The possible reactions occurring between carbonyl groups and nucleophilic sites on amino acid residues belonging to the keratin were investigated using as model compounds some aldehydes and amino acid derivatives. Raman and IR analyses on yak hair subjected to the straightening treatment with glyoxylic acid in different conditions were carried out. Scanning electron microscope (SEM) analyses were carried out on yak and curly human hair after each step of the straightening procedure.

RESULTS

The reactions between aldehydes and N-α-acetyl-L-lysine revealed the importance of the carbonyl electrophilicity and temperature to form imines. Raman and IR analyses on yak hair subjected to the straightening treatment evidenced rearrangements in the secondary structure distribution, conformational changes to the disulphide bridges, a decrease of the serine residues and formation of imines. It was also indicated that straightening produced major conformational rearrangements within the hair fibre rather than on the cuticle.

CONCLUSION

This investigation revealed the role played by the electrophilicity of the carbonyl on the straightener agent and of the temperature, closely related to the dehydration process. Raman and IR studies indicated the involvement of imine bonds and the occurrence of a sequence of conformational modifications during the straightening procedure. SEM analyses showed the effectiveness of the treatment at the cuticular level.

Role of Catecholamines in the Reproduction of Romanomermis culicivorax

The relative concentrations of catecholamine in the nervous system of the entomophilic nematode Romanomermis culicivorax were measured under different experimental conditions by a glyoxylic acid-induced fluorescence procedure. A greater concentration of catecholamine was recorded in the nervous system of adult males and females than in postparasitic juveniles. A higher concentration of catecholamine occurred in adults maintained in physical contact with the opposite sex than in those maintained in isolation. Adult males maintained with females in the same aqueous medium but physically separated by a barrier displayed a greater concentration of catecholamine in their nervous systems than did males maintained in isolation, but the catecholamine fluorescence intensity of such males was less than in males allowed physical contact with females. In adult males, the fluorescence intensity of catecholamine declined progressively during and after copulation. In adult females, the intensity of catecholamine remained constant before, during, and after copulation. Catecholamine(s) may play a role in regulating copulatory behavior, egg production, or oviposition.

An Improved Procedure for Synthesis of DL-4-Hydroxy-3-methoxymandelic Acid (DL-"Vanillyl"-mandelic Acid, VMA)

An improved procedure for synthesis of DL-4-Hydroxy-3-methoxymandelic Acid (DL-Vanillyl-mandelic Acid, VMA) entails slow addition of an ice-cold, aqueous solution of glyoxylic acid to an ice-cold alkaline solution of guaiacol, with efficient mechanical stirring. This one-step condensation procedure provides VMA in 68-75 percent yield.