C6 Aldehydes Research Articles

Decoding the Effects of High Hydrostatic Pressure and High-Temperature Short-Time Sterilization on the Volatile Aroma Profile of Red Raspberry Juice.

The loss of distinctive aromas due to sterilization significantly hinders efforts to enhance the sensory quality of fruit and vegetable juices. This study aimed to elucidate the impacts of high-hydrostatic pressure (HHP) and high-temperature short-time (HTST) sterilization methods on the loss of C6 aldehyde aroma-active compounds in red raspberry juice. External standard quantification and quantitative descriptive analysis (QDA) revealed a notable decline in the levels of hexanal and (Z)-3-hexenal following the HHP and HTST treatments (p < 0.05), resulting in a marked attenuation of the grassy aroma characteristic of red raspberry juice. Furthermore, a comprehensive examination of the precursors, pivotal enzymes, intermediates, and downstream aromas within the fatty acid metabolism pathway in different raspberry juice samples indicated that the C6 aldehydes loss induced by HHP and HTST sterilizations was primarily ascribed to the competitive inhibition of β-oxidation and the hindered enzymatic oxidation of fatty acids. These insights suggest that modifying sterilization protocols and enhancing enzymatic stability may help preserve the aroma integrity of raspberry juice. Our findings offer practical guidance for optimizing juice processing techniques to maintain flavor.

Hydroformylation of Lower Olefins and the Use of Oxo Synthesis Products Based on C4–C5 Aldehydes in the Production of Ester Lubricating Oils. Part 2. Rhodium Processes Developped in LLC «RN-RD Center»

Hydroformylation of Lower Olefins and the Use of Oxo Synthesis Products Based on C4–C5 Aldehydes in the Production of Ester Lubricating Oils. Part 2. Rhodium Processes Developped in LLC «RN-RD Center»

Stereoselective Synthesis of Volicitin and 9-D 1-Volicitin

AbstractThe synthesis of volicitin involved the condensation of l-(+)-glutamine with 17(S)-hydroxylinolenoic acid, derived from a Wittig reaction between the C10–C18 phosphonium salt and the C1–C9 aldehyde. The phosphonium salt was prepared through the alkynylation of a (Z)-allylic phosphate with an alkyne derived from (2S)-but-3-yn-2-ol. The deuterated aldehyde was derived with a 96% deuteration ratio by reduction of the C1–C9 methyl ester with NaBD4, followed by oxidation. Subsequently, 9-D 1-volicitin was synthesized from the monodeuterated aldehyde by using the Wittig reaction and condensation with l-(+)-glutamine.

Aldehyde-containing clays: a sustainable approach against the olive tree pest, Bactrocera oleae.

A set of organic/inorganic layered materials was obtained by functionalizing a montmorillonite-containing bentonite natural clay with linear aliphatic C6 or C7 aldehydes through a cost-effective and technologically simple incipient-wetness deposition method. The solids were investigated by means of a multi-technique approach (X-ray powder diffraction, XRPD, scanning electron microscopy, SEM, Fourier-transform infrared spectroscopy, FT-IR, thermogravimetric analysis, TGA, elemental analysis and solid-state nuclear magnetic resonance, ssNMR) to clarify the nature of the deposited organic species and the mode of interaction between the aldehyde and the clay. Since both natural clays and short-chain linear aldehydes find application as alternative strategies in the control of the olive fruit fly, Bactrocera oleae, the hybrid layered materials were tested under real-life conditions and their insect-inhibiting capability was evaluated in open-field trials on olive tree orchards in Tuscany, Central Italy. Specific tests were conducted to evaluate the resistance of the solids to weathering and their capability to provide a constant and long-lasting release of the bioactive ingredient. Aldehyde-containing bentonite clays have shown promising performance in controlling B. oleae infestation (with up to 86-95% reduction of affected olive fruits) in open-field trials across two years in two locations with different pedological and meteo-climatic characteristics.

A detailed high-pressure oxidation study of n-pentanal

Oxidation of n-pentanal is studied in a jet-stirred reactor at 10 atm for four dilute mixtures with equivalence ratios 0.3, 0.5, 1 and 2 and between 500–1150 K. A detailed kinetic sub-mechanism is developed and used along with the mechanisms representing the oxidation of two branched isomers of pentanal, namely 2- and 3-methylbutanal. At all conditions, n-pentanal showed a strong low-temperature reactivity and an NTC region. Among the experimentally observed species, ones related to the low-temperature oxidation of n-butyl radicals can be found, consolidating the importance of the (N-1) alkyl radicals in aldehyde chemistry. The kinetic mechanism showed good agreement against the data as well as other speciation data at atmospheric pressure from literature. The present data are also compared to previous similar studies on the oxidation of C3–C5 aldehydes in the same JSR and where n-pentanal shows the highest global reactivity.

The beneficial effects of the tobacco hydroperoxide lyase pathway in whitefly host adaptation

Plants respond to herbivore attack by emitting complex mixtures of volatile compounds to repel herbivores or attract predators and parasitoids. In this study, however, we revealed that tobacco green leaf volatiles (GLVs) were beneficial compounds for whitefly adaptation to host plants. Our study indicates that GLVs are closely associated with plant susceptibility to whiteflies. Whitefly infestation elevated the transcript of the hydroperoxide lyase (HPL) gene, one gene responsible for catalyzing the synthesis of C6 or C9 aldehydes from fatty acid hydroperoxides. Overexpression of HPL increased the emission of GLVs (hexanal, 1- hexanal, trans-2- hexanal and cis-3- hexanal) and resulted in improved performance for whiteflies. Exogenous application of GLVs promoted whitefly survival and fecundity and increased the plant's attraction to whiteflies. Thus, our study provides new insights into the role of the HPL pathway and GLVs in influencing herbivore adaptation to host plants.

Leaching and evolution of anthocyanins and aroma compounds during Cabernet Sauvignon wine fermentation with whole-process skin-seed contact

This study explores the leaching and evolution of anthocyanins and aroma compounds during wine-making, using an industrial-scale vinification of Cabernet Sauvignon with whole-process skin-seed contact. The results indicated that compounds within the same class displayed similar evolutionary patterns during fermentation. The extraction of anthocyanins, C6 aldehydes, and β-damascenes occurred continuously during cold soak, accompanied by the conversion of C6 aldehydes into alcohols and hydrolytic release of glycosidic β-damascenone. During alcoholic fermentation, pyranoanthocyanins, polymeric pigments, esters, benzene compounds, higher alcohols, and acids were generated. The concurrent occurrence of malolactic fermentation and prolonged maceration led to aromas associated with lactic acid bacteria metabolism. Finally, a comparison between free-run wine and pressed wine revealed high concentrations of C6 compounds and polymeric pigments with flavanol dimers in the pressed wine. These results can be used as a reference to optimize the vinification process to enhance the red due and fruity aromas of the wine.

Influence of Benzothiadiazole on the Accumulation and Metabolism of C6 Compounds in Cabernet Gernischt Grapes (Vitis vinifera L.).

Pre-harvest application of elicitors improves grape quality, specifically the phenolic compounds and color characteristics. Limited research has been conducted on the impact of elicitors on the C6 compounds found in grapes. This is due to lack of comprehensive studies examining the combined effects of bound aroma compounds, enzyme activity, and substrate availability. This study aimed to assess the impact of benzothiadiazole (BTH) on the physicochemical properties and C6 compounds of Cabernet Gernischt grapes during ripening. Compared with the control group (CK), BTH treatment significantly increased the 100-berry weight, skin/berry ratio, pH, total phenolic content, and total flavonoid content in ripe grapes. Additionally, BTH treatment led to significant reductions in reducing sugar, total soluble solids, titratable acidity, linoleic acid, linolenic acid, and free C6 aldehydes. Furthermore, BTH treatment significantly decreased the contents of free C6 alcohols and increased the levels of free and bound C6 esters. BTH treatment also increased the activities of lipoxygenase, alcohol dehydrogenase, and alcohol acetyltransferase enzymes, while it decreased the activity of hydroperoxide lyase enzyme. The application of BTH resulted in changes to the physicochemical properties and levels of C6 compounds in Cabernet Gernischt grapes by up-regulating enzyme activity and down-regulating precursors.

Suitable crop loading: An effective method to improve "Shine Muscat" grape quality.

Berry thinning was applied to control crop load of "Shine Muscat" grape variety. Primary and secondary metabolites released during berries development were monitored, and the correlation between physicochemical parameters and core aroma compounds was analyzed. Results revealed a significant increase in single-berry weight and sugar-acid ratio of berries under low crop load conditions. Furthermore, phenolic content and antioxidant activity under low crop load were significantly higher than those of the other groups. Grapes with low crop loads also exhibited better aroma characteristics and higher sensory scores than those of the other groups, chiefly due to significantly increased terpene and C13-norisoprenoid contents and substantially decreased C6 compound and aldehyde contents. Moreover, correlation analysis revealed total soluble solid accumulation was positively correlated to terpene accumulation, while hexanal, 2-hexanal, (E)-2-hexanal, and (E)-2-octenal were positively correlated with titratable acidity content. Thus, better grape quality could be achieved by precisely controlling berry crop load.

New insights into the off-flavor improvement of soymilk by three grinding processing: Dry-blanching grinding, wet-blanching grinding, and wet-anaerobic grinding

Advances in grinding strategies have been beneficial to eliminating the off-flavor of soymilk and improving the quality soy products. Herein, four grinding processing, dry-blanching grinding (D-BG), wet-blanching grinding (W-BG), wet-anaerobic grinding (W-AG) and traditional grinding (TG) were employed and found to impose a significant impact on off-flavor components, accompanied by changes of hydroperoxides and free radicals. The results showed that all three methods could significantly hinder the formation of C6 aldehydes. C8 Alcohols and (E)-2-heptenal could be removed by D-BG, but lipids in dehulled soybean were prefer to be oxidized during storage, resulting in the accumulation of hydroperoxides and radicals. W-BG and W-AG have higher levels of 1-octen-3-ol, and soaking at an alkaline pH and increasing the number of rinses is beneficial for its removal. Gas chromatography-olfaction-mass spectrometry (GC-O-MS) combined with sensory evaluation showed that off-flavor profile of d-BGS, W-BGS and W-AGS was different. D-BG and W-AG possessed better flavor quality.

Fatty acid metabolism and C9 aldehyde biosynthesis are involved in ε-poly-l-lysine-induced citrus fruit resistance to Penicillium digitatum

Citrus fruit were easily infected by Penicillium digitatum, and caused green mold rapidly, resulting in enormous post-harvest losses. ε-poly-l-lysine (ε-PL) was generally regarded as a safe (GRAS) substance. Besides, it was proved to have a dual effect on harming fungi and triggering fruit defense responses. Fatty acid metabolism is closely related to fruit defense response. However, little is known about how ε-PL affected fatty acid metabolism in citrus fruit. Here, we found that ε-PL increased the expression of CsFATA, CsACSL, CsFAD2, CsFAD3, CsLOX2S, and CsHPL in fatty acid metabolism, decreasing oleic acid levels and enhancing linoleic and linolenic acid levels. Additionally, ε-PL enriched the activities of LOX and HPL during the oxidative decomposition of fatty acids, and activating C9 aldehyde biosynthesis. Interestingly, ε-PL combined with (2E,4E)-nonadienal (C9 aldehyde) would improve the inhibitory effect against Penicillium digitatum. And the combined bio-fungicide significantly delayed the citrus green mold compared to single concentrations of the individual components. These results suggested that ε-PL improved citrus fruit defense responses through fatty acid-mediated defense responses. Combined bio-fungicide consisting of ε-PL and (2E,4E)-nonadienal have an excellent prospect for controlling citrus green mold.

Optimizing the First Step of the Biocatalytic Process for Green Leaf Volatiles Production: Lipase-Catalyzed Hydrolysis of Three Vegetable Oils.

Green leaf volatiles (GLVs), including short chain volatile aldehydes, are widely used in the flavor and food industries because of their fresh aroma. To meet the growing demand for natural GLVs with high added value, the use of biocatalytic processes appears as a relevant application. In such processes, vegetable oils are bioconverted into GLVs. First, the triacylglycerols of the oils are hydrolyzed by a lipase. Then, the free polyunsaturated fatty acids are converted by a lipoxygenase. Finally, volatile C6 or C9 aldehydes and 9- or 12-oxoacids are produced with a hydroperoxide lyase. Optimization of each biocatalytic step must be achieved to consider a scale-up. In this study, three oils (sunflower, hempseed, and linseed oils) and three lipases (Candida rugosa, Pseudomonas fluorescens, and Rhizomucor miehei lipases) have been tested to optimize the first step of the process. The experimental design and response surface methodology (RSM) were used to determine the optimal hydrolysis conditions for each oil. Five factors were considered, i.e., pH, temperature, reaction duration, enzyme load, and oil/aqueous ratio of the reaction mixture. Candida rugosa lipase was selected as the most efficient enzyme to achieve conversion of 96 ± 1.7%, 97.2 ± 3.8%, and 91.8 ± 3.2%, respectively, for sunflower, hempseed, and linseed oils under the defined optimized reaction conditions.

Characterization of volatile compounds of Gök Üzüm raisins produced from grapes pre-treated with different dipping solutions

BackgroundRaisins contain a wide range of secondary metabolites, including volatile compounds that may contribute to the health benefits and preference of consumers. To our knowledge, this is one of the first studies concerning the analysis of volatile compounds in raisin. The goal of this study was to compare volatile composition of Gök Üzüm (Vitis vinifera L.) raisins produced from grapes dried before the application of two pre-treatments solutions: wood ash (WA) and potassium carbonate (K2CO3).ResultsGök Üzüm raisins produced from grapes dipped into the WA solution presented higher contents of most of the studied volatile compounds (including the total contents of C6 compounds, alcohols, benzenoids, esters, aldehydes, terpenes and C13 norisoprenoids) and lower contents of (Z)-2-hexenol and 2-hexenoic acid than the raisins produced from grapes dipped into K2CO solutions. Gök Üzüm raisins were characterized by fruity, floral and grass aromas according to their odor activity values. Drying Gök Üzüm grapes after the treatment of WA solutions promotes a higher aromatic composition compared to K2CO solutions.ConclusionThese findings can greatly assist raisin producers in deciding which dipping solution to use before using a dipping solution to dry the grapes.Graphical

Hydroformylation of Lower Olefins and the Use of Oxo Synthesis Products Based on C4–C5 Aldehydes in the Production of Ester Lubricating Oils. Part 1. Catalysts and Industrial Processes

Hydroformylation of Lower Olefins and the Use of Oxo Synthesis Products Based on C4–C5 Aldehydes in the Production of Ester Lubricating Oils. Part 1. Catalysts and Industrial Processes

Aroma volatile characterisation and gene expression analysis during fruit development and ripening of five pear (Pyrus L.) species

ABSTRACT Bartlett, Hongnanguo, Korla Xiangli, Dangshansuli and Housui are representative cultivars from the five cultivated pear species that were chosen to identify aromatic compounds in fruit during developmental, mature and storage periods. We explored the expression levels of aroma formation-related genes during developmental and storage periods. The concentrations of the aromatic compounds first decreased, then increased in all five cultivars. For the climacteric pears, Bartlett and Hongnanguo, the increase continued to optimal sensory quality (OSQ), whereas those for the non-climacteric pears, Korla Xiangli, Dangshansuli and Housui decreased. Aldehydes contributing the 'green' odour and 1,4-benzoquinone were the primary components during early and middle developmental periods. Esters contributing the 'fruity' and 'sweet' odour, were the primary components in Bartlett, Hongnanguo and Korla Xiangli fruits during storage and at OSQ. Methyl- and ethyl-(E, Z)-2,4-decadienoate (pear-like odour), ethyl caproate (liquor odour), and hexyl acetate (fruity odour) were the key characteristic odorants in mature pear fruits of Bartlett, Hongnanguo and Korla Xiangli, respectively. Alcohol dehydrogenase (PbrADH-1 and PbrADH-2) and lipoxygenase (PbrLOX3) might participate in the formation of C6 and C9 volatile aldehydes and alcohols. The aroma content and volatiles of pear fruits during development and storage probably revealed a common pattern.

Different reactivities of H3 O+ (H2 O)n with unsaturated and saturated aldehydes: ligand-switching reactions govern the quantitative analytical sensitivity of SESI-MS.

The detection sensitivity of secondary electrospray ionisation mass spectrometry (SESI-MS) is much lower for saturated aldehydes than for unsaturated aldehydes. This needs to be understood in terms of gas phase ion-molecule reaction kinetics and energetics to make SESI-MS analytically more quantitative. Parallel SESI-MS and selected ion flow tube mass spectrometry (SIFT-MS) analyses were carried out of air containing variable accurately determined concentrations of saturated (C5, pentanal; C7, heptanal; C8 octanal) and unsaturated (C5, 2-pentenal; C7, 2-heptenal; C8, 2-octenal) aldehyde vapours. The influence of the source gas humidity and the ion transfer capillary temperature, 250 and 300°C, in a commercial SESI-MS instrument was explored. Separate experiments were carried out using SIFT to determine the rate coefficients, k73 , for the ligand-switching reactions of the H3 O+ (H2 O)3 ions with the six aldehydes. The relative slopes of the plots of SESI-MS ion signal against SIFT-MS concentration were interpreted as the relative SESI-MS sensitivities for these six compounds. The sensitivities for the unsaturated aldehydes were 20 to 60 times greater than for the corresponding C5, C7 and C8 saturated aldehydes. Additionally, the SIFT experiments revealed that the measured k73 are three or four times greater for the unsaturated than for the saturated aldehydes. The trends in SESI-MS sensitivities are rationally explained by differences in the rates of the ligand-switching reactions, which are justified by theoretically calculated equilibrium rate constants derived from thermochemical density functional theory (DFT) calculations of Gibb's free energy changes. The humidity of SESI gas thus favours the reverse reactions of the saturated aldehyde analyte ions, effectively suppressing their signals in contrast to their unsaturated counterparts.

The Dual Benefit of Plant Essential Oils against Tuta absoluta.

Plant essential oils (PEOs) are being studied as a potential alternative to synthetic pesticides in agriculture. PEOs have the potential to control pests both directly, by being toxic or repellent to pests, and indirectly, by activating plant's defense mechanisms. In this study, the effectiveness of five PEOs (Achillea millefolium, Allium sativum, Rosmarinus officinallis, Tagetes minuta, and Thymus zygis) on controlling Tuta absoluta and their impact on the predator Nesidiocoris tenuis was examined. The study revelead that PEOs from A. millefolium and A. sativum-sprayed plants significantly reduced the number of T. absoluta-infested leaflets and did not affect the establishment and reproduction of N. tenuis. Additionally, the spraying of A. millefolium and A. sativum increased the expression of defense genes in the plants, triggering the release of herbivory-induced plant volatiles (HIPVs), such as C6 green leaf volatiles, monoterpenes, and aldehydes, which can be messengers in tritrophic interactions. The results suggest that PEOs from A. millefolium and A. sativum can provide a dual benefit for controlling arthropod pests, as they can directly exhibit toxicity against these pests while also activating plant defense mechanisms. Overall, this study provides new insights into using PEOs as a sustainable solution for controlling pests and diseases in agriculture, by reducing synthetic pesticides and promoting the use of natural predators.

Assessment of aldehyde contributions to PTR-MS m/z 69.07 in indoor air measurements

PTR m/z 69.07 commonly attributed to isoprene suffers interference from C5–C10 aldehydes indoors, especially when ozone is present. The contribution of nonanal could be quantified by using the protonated molecular ion, unlike the other aldehydes.

Effect of sweeteners and carbonation on aroma partitioning and release in beverage systems

The effect of monosaccharides (glucose, fructose and galactose) and disaccharides (sucrose and lactose) at 10, 20 and 30 % w/v on the in-vitro aroma partitioning of C4 – C10 aldehydes and ethyl esters, as well as limonene (concentration of aroma compounds at 1 μg mL−1), was studied using atmospheric pressure chemical ionisation–mass spectrometry. An increase in sugar concentration from 0 to 30 % w/v resulted in a significant increase in partitioning under static headspace conditions for the majority of the compounds (p < 0.05), an effect generally not observed when 10 % w/v sucrose was substituted with low-calorie sweeteners (p > 0.05). The complexity of the system was increased to model a soft drink design – comprising water, sucrose (10, 20 and 30 % w/v), acid (0.15 % w/v), carbonation (∼7.2 g/L CO2) and aroma compounds representative of an apple style flavouring, namely ethyl butanoate and hexanal (10 μg mL−1 each). Although the addition of sucrose had no significant in-vivo effect, carbonation significantly decreased breath-by-breath (in-vivo) aroma delivery (p < 0.05). To understand the physical mechanisms behind aroma release from the beverage matrix, the effect of sucrose on the kinetics of the matrix components was explored. An increase in sucrose concentration from 0 to 30 % w/v resulted in a significant decrease in water activity (p < 0.05), which accounted for the significantly slower rate of self-diffusion of aroma compounds (p < 0.05), measured using diffusion-ordered spectroscopy–nuclear magnetic resonance spectroscopy. No significant effect of sucrose on carbon dioxide volume flux was found (p > 0.05).

Evaluation of dynamic changes and formation regularity in volatile flavor compounds in Citrus reticulata ‘chachi’ peel at different collection periods using gas chromatography-ion mobility spectrometry

Citrus reticulata ‘Chachi’ is a commercially important and predominantly cultivated tangerine cultivar in Xinhui County, Guangdong, China. The dried C. reticulata ‘Chachi’ pericarp (CRCP), known as “Guangchenpi” in Mandarin has unique flavor properties, and has been used as a highly valuable nutritional food source and in traditional medicine for centuries. In this study, headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) and partial least squares-discriminant analysis (PLS-DA) were adopted to rapidly and comprehensively evaluate the flavor compounds of dried CRCP, and to identify their dynamic changes at different fruit picking stages. Results revealed a total of 71 volatile compound in the samples at six different fruit picking stages. The C6–C9 alcohols and aldehydes with aromatic green grass profiles had higher concentrations in the early fruit picking stages (from July to October), while most terpenes, ketones, and esters with typical aromas of mature flowers and fruits were highly accumulated in the late fruit picking stages (from November to December). PLS-DA results showed that samples picked in different stages could effectively be divided into relatively independent clusters, and the variable importance in projection (VIP) models identified 12 representative flavor compounds, which could be used as flavor markers for distinguishing CRCP samples picked at different stages.