Generation Of Volatile Compounds Research Articles

The impacts of different roasting degrees on aroma compounds profiles of moringa seed kernels and its oil

The impacts of different roasting conditions (temperature and duration) on aroma compounds profiles of moringa seed kernels (MSK) and its oil (MSKO) were assessed. We found that medium and dark roasting (roasting temperatures ≥175 °C) induced significant increases in total volatile concentrations in both MSK and MSKO. The generation of volatile compounds during roasting was attributed to the complex thermal reactions, including Maillard reaction, Strecker degradation, caramelisation and lipid thermal oxidation and degradation. Among the detected aroma compounds, newly generated N-containing heterocyclic compounds, O-containing heterocyclic compounds, and sulfur-containing compounds were the primary contributors to the volatile profiles. The sensory results demonstrated that roasting could improve the aroma complexity of MSK and its oil, which may expand their application in the food industry.

Formation of levoglucosenone and furfural from three different carrageenans via acid-catalyzed pyrolysis in polyethylene glycol

To further develop the potential for carrageenan-use in a seaweed biorefinery, the acid-catalyzed pyrolysis of kappa-, iota- and lambda-carrageenans has been studied in polyethylene glycol (PEG). Using differential scanning calorimetry, it was found that decomposition temperatures for the three polysaccharides were broadened and lowered by 33–60 °C in the presence of H2SO4 and PEG compared to polysaccharide alone. Levoglucosenone (LGO) and furfural were the major products from all polysaccharides with LGO yields of 21.3 mg/gcarr (3.5 mol%), 10.7 mg/gcarr (2.2 mol%) and 3.9 mg/gcarr (1 mol%) and furfural yields of 5.9 mg/gcarr (1.3 mol%), 2.8 mg/gcarr (0.7 mol%) and 1.2 mg/gcarr (0.4 mol%), for kappa-, iota- and lambda-carrageenans, respectively. Total sulfate inversely correlated with the generation of volatile compounds, and the 3,6-anhydro structure may encourage the formation of the major products during the acid-catalyzed pyrolysis of carrageenan in PEG.

Contribution of critical doses of iprovalicarb, mepanipyrim and tetraconazole to the generation of volatile compounds from Monastrell-based wines

The individual effects of iprovalicarb, mepanipyrim, and tetraconazole on the volatile composition and aromatic profile of Monastrell-based wines were evaluated. To date, no studies about the effect of these fungicides on Monastrell-based wines are available, and the effect on other grape varieties is also unknown. Fungicides were added separately in the cellar to the grape must at two concentration levels (4 and 10 mg/kg for iprovalicarb and mepanipyrim and 1 and 2.5 mg/kg for tetraconazole). The aromatic composition of the final wines was analysed by gas chromatography using flame ionisation and ion trap mass selective detectors.In the presence of fungicides, the most significant variations were observed for isoamyl acetate and 2-phenylethyl acetate (increasing between 20 and 43% compared with the control wine) and ethyl caprate and caprylate (increasing between 12 and 68%). Consequently, treated wines showed a higher global odourant intensity, with increased fresh fruit notes.

Biochemical, microbiological and technological characteristics of type II sourdoughs produced with lactic acid bacteria single-strains

The interplay between biochemical characteristics and the generation of volatile compounds in 11 type II sourdough fermented by single strains of lactic acid bacteria (LAB) was studied. Samples were collected at 0, 6, 9, 12, 15, 18 and 24h for analyses of microbial growth, pH, titratable acidity and CO2 production. During the first 12h, the LABs entered the stationary phase, and the formation of organic and carboxyl acids, alcohols, and esters were observed. Although acidity is an important characteristic of sourdough, in this work increasing the acetic acid content decreased yeast growth and the CO2 retention capacity of the doughs. The main carbohydrate consumed by autochthonous yeast was influenced by the LAB added (homo-or heterofermentative), as observed by correlation analysis. Maltose and glucose showed a strong and negative correlation with the yeast cell density in the dough fermented by homo and heterofermentative LAB, respectively. Moreover, LAB had an important effect on the aromatic profile, being the alcohols, aldehydes, alkanes, organics acids and esters mainly groups characterized. Altogether, 100 different volatile compounds were identified; however, each dough had a different volatile profile. This study shows, for the first time, the influence of a single strain of LAB on the characteristics of type II sourdough.

Effect of heat treatment on amino acids and volatile compounds of enzymatic pork trimmings hydrolysate supplemented with xylose and cysteine

In this research, the effects of heat treatment together with xylose and cysteine addition on the amino acid changes and volatile compound generation in non-enzymatic pork trimmings extract (NPE) or enzymatic pork trimmings hydrolysate (EPH) were studied. Enzymatic hydrolysis significantly increased the total amino acid content and provided necessary precursors for the thermal reactions. The addition of xylose assisted the browning process while the cysteine addition partially inhibited the formation of brown colour in both NPE and EPH. The addition of both cysteine and xylose significantly increased the formation of sulfur-containing volatile flavour compounds in EPH samples, but not in NPE samples. The characteristic “roasted meat” like aromatic volatile compounds, in particular, 2-furfurylthiol, were only detected in EPH samples at 8.13 ng/mL, when both xylose (35 mg/mL) and cysteine (10 mg/mL) were added.

Fatty Acid Composition and Volatile Profile of longissimus thoracis et lumborum Muscle from Burguete and Jaca Navarra Foals Fattened with Different Finishing Diets.

The present study evaluated the effect of breed, Jaca Navarra (JN) vs. Burguete (BU), and finishing diet, conventional concentrate—diet 1 (D1) vs. silage and organic feed—diet 2 (D2), on the fatty acid composition and volatile profile of longissimus thoracis et lumborum muscle from forty-six foals. For this, foals were reared under a semi-extensive system and slaughtered at about 21 months of age. The outcomes showed that breed and finishing regime had a significant (p < 0.05) effect on the lipid and volatile profile of foal meat. In particular, JN foals reported higher polyunsaturated fatty acid contents and better nutritional indices in line with the health guidelines; whereas, BU and D1 groups generated higher amounts of total volatile compounds. However, it was the diet to occupy a central role in this study. Indeed, diet 2, due to its “ingredients” and composition, not only ameliorated the lipid profile of foal meat, but also reduced the generation of volatile compounds associated with lipid oxidation and minimized off-flavors. Thus, this diet could give an added value to the aromatic perception of meat and improve its sensorial acceptability.

The age-dependent variations for fatty acid composition and sensory quality of chicken meat and associations between gene expression patterns and meat quality

Chicken meat is accompanied by physicochemical alterations during the process of growth and development, resulting in differences of nutritional value and meat flavor. The primary objective in the present study was to determine the mode of action on intramuscular fat content, serum lipid levels, fatty acid composition, and volatile flavor components of chicken meat. Negative correlations were observed between PUFA and aldehyde compounds and positive correlations were observed between PUFA and heterocyclic compounds. Intramuscular fat was correlated with only three volatile flavor compounds, indicating that the generation of volatile compounds was more dependent on the fatty acid composition rather than total intramuscular fat content. To explore the potential valuable biomarkers for sensorial and nutritional quality of chicken meat, a total of 12 temporal gene expression patterns were identified by transcriptomics. Module eigengenes 2 and 11 were significantly correlated with C14:0, C16:0, C18:1 cis-9, C18:2 cis-6, C18:3 n-3, C20:2, C20:3 n-6, C20:4 n-6, C22:6 n-3, C24:0, C24:0, C24:1, EFA, MUFA, PUFA, PUFA n-6 contents, and MUFA/SFA ratio, while were only significantly correlated with 1-octanol and 2-ethylhexyl glycidyl ether, respectively. Moreover, functional analysis of correlated-trait module eigengenes provided information on the explanation for the age-dependent variations for fatty acid composition and sensory quality of chicken meat.

Cocoa bean turning as a method for redirecting the aroma compound profile in artisanal cocoa fermentation

Two artisanal fermentation processes for Criollo cocoa beans with different turning start times (24 h and 48 h) were studied. The aromatic profile of cocoa turned every 24 h (B1) displayed volatile compounds associated with fermented, bready, and fruity aromas. When cocoa beans were fermented with a different turning technique with a start time of 48 h (B2), they provided volatile compounds mainly associated with descriptors of floral, woody, sweet, fruity and chocolate aromas. The turning start time of 48 h stimulated a microbial profile dominated by yeast such as Hanseniaspora opuntiae, Pichia manshurica, and Meyerozyma carpophila, favoring the production of several key aroma markers associated with cocoa bean fermentation quality, such as phenylethyl acetate, 2-phenylacetaldehyde, 3-methylbutanal, 2-phenylethyl alcohol, 2,3-butanedione, 3-methylbutanoic acid, and 2-methylpropanoic acid, while an immediate turning start time (24 h) favored an aerobic environment that stimulated the rapid growth of Acetobacter pasteurianus, Bacillus subtilis and a higher biodiversity of lactic acid bacteria (LAB) (e.g., Lactobacillus plantarum and Pediococcus acidilactici), which increased the production of ethyl acetate and 3-hydroxy-2-butanone. Volatile compound generation and microbial populations were evaluated and analyzed by multivariate analysis (principal component analysis and partial least squares discriminant analysis) to find correlations and significant differences. This study shows that the method of turning Criollo cacao beans can lead to the formation of desirable aromatic compounds.

The generation of volatiles in model systems containing varying casein to whey protein ratios as affected by low frequency ultrasound

The application of low frequency ultrasound has been intensively explored within the dairy field to improve product properties and processing efficiency over conventional treatments. However, the generation of undesirable volatile compounds during sonication can negatively influence the uptake of this technique within the dairy industry. Therefore, the present study was attempted to investigate the formation of volatile compounds in model milk systems containing 4% w/w fat and 3.5% w/w milk proteins with varying ratios of casein to whey proteins (50:50, 60:40, 80:20) as affected by low frequency ultrasound (20 kHz). The samples were treated for 1 and 10 min which were corresponding to energy densities of 9.54 J ml−1 and 190.8 J ml−1, respectively. The generation of volatile compounds was mainly influenced by the sonication time for all milk samples irrespective of the casein to whey ratios. The fatty acid chains and ester groups of milk fat and lipid-protein complexes increased with the increase in sonication time for all samples regardless of the casein to whey ratios. In contrast, milk proteins altered their secondary structure with an increase in random coil structure and concomitant decrease of α-helix, β-turn and β-sheet as affected both by sonication time and casein to whey ratios.

Ultrasonic assisted glass bead loaded gas liquid separator-photochemical vapor generation-T-shaped slotted quartz tube-flame atomic absorption spectrophotometry system for antimony determination in tap water and wastewater samples

In this study, optimization and validation of ultrasonic assisted glass bead loaded gas liquid separator-photochemical vapor generation-T-shaped slotted quartz tube-flame atomic absorption spectrophotometry (UA-GLS-PVG-T-SQT-FAAS) system was performed for the determination of antimony in real samples. Volatile derivatives of antimony were generated and separated from liquid matrix by combination of a UV photoreactor and gas–liquid separation. Optimization of all variable parameters which effect volatile compound generation and separation efficiency such as low molecular weight organic acid type and concentration, ultraviolet irradiation period, gas–liquid separator design, carrier gas flow rate and sample volume were evaluated one at a time keeping the others constant. Limit of detection and quantification were calculated as 47 and 157 µg L–1, respectively. Detection power of the developed method was enhanced about 58 folds compared to conventional FAAS system over LOD comparison. In addition, applicability/accuracy of the developed method was checked by spiking experiments in tap and wastewater samples and percent recovery results were found in the range 83.4–106.4%.

Pulsed electric fields affect endogenous enzyme activities, respiration and biosynthesis of phenolic compounds in carrots

Abstract Pulsed electric fields (PEF) can be applied to induce accumulation of bioactive compounds in plant tissues to obtain commodities with health-promoting properties. However, causes of this accumulation are not fully understood as it may result from either an improvement in extraction or an activation of stress-related biosynthetic pathways. The objective of this study was to investigate the effects of PEF on the physiological response and elucidating the causes underpinning changes in carrot phenolic contents. Respiration rate, oxidative and pectinolytic enzyme activities, synthesis, and content of phenolic compounds were evaluated in PEF-treated (580 J kg−1) carrots after treatment and through storage (12, 24 and 36 h) at 4 °C. The highest production of CO2 and volatile organic compounds was observed 12 h after PEF treatment whereas the largest increases in total phenolic content (80.2 %), p-OH-benzoic (94.7 %), chlorogenic acid (74.9 %) and ferulic acid (52.2 %) occurred 24 h after treatment. Enhanced in phenylalanine ammonia lyase activity indicated that the increase in phenolic compounds may be mainly due to the triggering of biosynthesis pathways instead of structural modifications of the food matrix. Electropermeabilization also induced considerable changes in pectinolytic enzyme activities (increases in pectinmethylesterase and decreases in polygalacturonase) whereas no clear trends were observed for oxidative enzyme activities (peroxidase and polyphenol oxidase) during storage. These results suggest that volatile compounds generation, changes in respiration rate and the biosynthesis of phenolic compounds are induced by PEF application, as a plant defence response to stress.

Metabolomics analyses of the combined effects of lactic acid bacteria and Penicillium camemberti on the generation of volatile compounds in model mold-surface-ripened cheeses

The flavor of white mold cheese is attributed to the formation of aroma compounds associated with complex effects of bacteria and fungi, resulting in difficulties in flavor design for new cheeses. This study aimed to identify the microbial basis of flavor by identifying the combined effects of LD type lactic acid bacteria (LAB) starters and Penicillium camemberti on the generation of metabolites during the ripening process. Metabolomics analyses were performed on three model cheeses: normal cheese, no-mold cheese with only LAB, and no-LAB cheese with only white mold. Aroma compounds and their potential precursors were analyzed using headspace solid-phase microextraction-gas chromatography/mass spectrometry (GC/MS) and solvent extraction-GC/MS, respectively. Measurements during ripening and multivariate analyses on the data revealed the relationship between the microorganisms and metabolic activities, which were classified into four groups: metabolites generated by LAB and degraded by P.camemberti; metabolites generated by P.camemberti and degraded or inhibited by LAB; metabolites generated by P.camemberti and enhanced by LAB; and metabolites exhibiting no interaction between P.camemberti and LAB. The characteristic compounds in LAB and white mold cheeses were mainly products of sugar and protein metabolism, respectively. The involvement of fatty acids, methyl ketones, and secondary alcohol metabolic pathways in the late-ripening stage was confirmed, and the profiles of volatile metabolites contributing to the characteristic aroma of the white mold cheese in the fermentation process were also confirmed.

Cultivar differences in lipoxygenase activity affect volatile compound formation in dough from wheat mill stream flour

Flavor, an important aspect of wheat (Triticum aestivum) dough products, forms during preparation and is affected by the generation of volatile compounds. These compounds are produced mainly by the oxidation of unsaturated fatty acids by lipoxygenase (LOX). Here, we analyzed the volatile compounds emitted from dough made from wheat mill stream flour to clarify the cultivar differences in LOX distribution and its effect on the formation of volatile compounds. LOX activity increased with ash content, and the rate of increase was significantly higher for Norin 61 than for other wheat cultivars. The volatile compound profiles were analyzed by principal component analysis, with almost all volatile compounds correlated to ash content. The volatile compounds in some Norin 61 streams, however, were more characteristic of the outer layer of wheat kernels than those in the other cultivars. Since the ash content among cultivars was similar, the characteristic volatile compound profiles of Norin 61 were presumed to be caused by higher LOX activity in this cultivar. In conclusion, the characteristic volatile compound profiles in each cultivar are due to the differences of LOX activity.

Effect of the Calpain System on Volatile Flavor Compounds in the Beef Longissimus lumborum Muscle.

The present study was designed to investigate the effects of calpain system on the formation of volatile flavor compounds in Hanwoo beef. In the first experiment (exp.1), Longissimus lumborum (LL) muscle samples were injected with solutions containing 50 mM CaCl2 or 50 mM ZnCl2 and 154 mM NaCl respectively, and aged for 7 d at 4°C. In the second experiment (exp.2), the ground LL muscle was incubated with the aforementioned solutions containing cathepsin inhibitor. The injection with CaCl2 solution greatly elevated the calpain activity and concomitantly, significantly decreased the Warner-Bratzler shear force (p<0.05). The pH, meat color and cooking loss did not differ (p>0.05) between the treatment groups. A total of 51 volatile compounds were identified using the solid phase microextraction with gas chromatography (SPME-GC). Results on volatile analyses from the both experiments showed that the injection with calcium ions led to significant increase (p<0.05) concentrations of pyrazines and sulfuric compounds. These results coincide with a higher rate of protein degradation due to the CaCl2 injection as compared to the control group. Significantly (p<0.05) higher levels of lipid oxidation derived-aldehydes were found in the samples with ZnCl2. The exp.1 showed that cathepsin inhibitors had no effect on the formation of volatile flavor components after 7 d of aging. These results imply that the proteolytic activity of the calpain system is associated with generation of volatile compounds of chiller-aged beef, while the role of cathepsins is likely very limited.

Effects of the diameter on physico-chemical, microbiological and volatile profile in dry fermented sausages produced with two different starter cultures

Abstract Four batches of Milano-type dry fermented sausages were industrially produced to evaluate the effects of two different lactic acid bacteria starter cultures ( Lactobacillus sakei and Pediococcus pentosaceus ) and diameter on physico-chemical, microbiological and aroma characteristics during processing and in the final products. Values of a w and pH were similar in the final sausages. Lactic acid bacteria counts were high and slightly influenced by the diameter, while higher concentrations of staphylococci were found in small sausages. The diameter had a strong influence on the formation of volatile organic compounds, as revealed by PCA analysis. The main differences regarded ketones (acetone, 2-butanone, 3-hydroxy-2-butanone and 2,3-butandione) and aldehydes (mainly hexanal). The influence of starter cultures was less evident, also due to the presence of indigenous L . sakei in the sausages inoculated with pediococci. Nevertheless, the choice of L . sakei or P. pentosaceus as starter culture showed a direct effect on some of the main process parameters (fermentation and acidification rate) and generation of volatile compounds. The results evidenced the need to optimize the process to increase starter culture performances.

Contribution of Histidine and Lysine to the Generation of Volatile Compounds in Jinhua Ham Exposed to Ripening Conditions Via Maillard Reaction.

Jinhua ham is a well-known traditional Chinese dry-cured meat product. However, the formation of the compounds comprising its special flavor is not well understood. Our results indicate that Maillard reactions occur in Jinhua ham under ripening conditions. This work illustrates the contribution of Maillard reactions to the flavor of Jinhua ham.

Study of the Effect of a Polymeric Compatibilizing Agent on the Flame Retardancy and Tensile Properties of High Density Polyethylene/Magnesium Hydroxide Compositions

The effect of using a compatibilizer, such as maleic anhydride grafted polyethylene (PEgMA), on the flame retardancy and mechanical (tensile) properties of HDPE nanocomposites with silane modified Mg(OH)2 was studied. The silane modification of Mg(OH)2 was confirmed by FTIR. Filler dispersion was characterized by scanning electron microscopy in transmission mode (STEM) and the effect of filler on mechanical properties was also evaluated. The flame retardant properties were evaluated by flammability tests (Underwriters Laboratory – UL‐94) and cone calorimeter. The mechanism by which the use of PEgMA compatibilizer improves the flame retardancy of HDPE/Mg(OH)2 was studied. Through the simultaneous TGAIR analysis, it was found that when using PEgMA, the flame retardant properties of HDPE/Mg(OH)2 are modified, due to the generation of volatile compounds in the thermal decomposition.

Study on the volatile compounds generated from lipid oxidation of Chinese bacon (unsmoked) during processing

In order to investigate the generation of aroma in Chinese bacon (unsmoked), the changes of lipolysis, lipid oxidation, and volatile compounds derived from lipid oxidation (VCDFLO) during processing were analyzed. The results showed that acid lipase activity decreased during the entire process, while neutral lipase and lipoxygenase (LOX) increased from raw meat to the 1 day of dry‐ripening then decreased. Phospholipase increased during dry‐curing then decreased during dry‐ripening. Thiobarbituric acid reactive substances increased from raw meat to the 7 days of dry‐ripening thereafter decreased. Total free fatty acids increased at the end of 1 day of dry‐ripening and decreased subsequently. Thirty‐five VCDFLO were identified; the total peak area of these compounds increased by almost double at the 4 days of dry‐ripening than raw meat and indicated 47.37–50.85% of total 78 volatile compounds in the final products. In conclusion, VCDFLO generation was attributed to lipid‐related enzymes and contributed mainly to the aroma.Practical applications: Chinese bacon (unsmoked) usually produced from high intramuscular fat pork has more intense and long‐lasting aroma, since intramuscular triglycerides are good precursors for most volatile compounds. Understanding the mechanism of aroma formation related to lipid oxidation could help us to improve the product quality and optimize the duration of processing. Therefore, the present work identified the characteristic flavor compounds and provided the changing regularity of these compounds at various stages to facilitate the generation of them by regulating lipases and lipoxygenase (LOX) activities.The work showed that neutral lipase and lipoxygenase (LOX) played important roles during dry‐curing and dry‐ripening. The regulation of lipases and LOX activities can facilitate the generation of volatile compounds of Chinese bacon (unsmoked).

Influence of different flours and starches on gluten-free bread aroma.

The aim of this research was to study the effect of different gluten-free flours (yellow and white corn, rice, oat, teff, buckwheat, amaranth and quinoa) and starches (wheat, corn and potato) on the generation of volatile compounds in the fermented doughs and crumbs. Volatile compounds were analyzed by static headspace-gas chromatography/mass spectrometry (SHS-GC/MS). Nine fermentation and lipid oxidation volatile compounds were evaluated, which were found to be the same from dough to crumb but vary in levels. Concentrations of compounds produced during fermentation were higher in doughs whereas those from lipid oxidation were higher in crumbs. The type of flour/starch affected the concentration of these volatile compounds. The proportions of ethanol and 2/3-methylbutanol (fermentation compounds) were higher in dough from yellow and white corn, rice and oat while the proportions of hexanal, 1-pentanol and 2,4-decadienal (lipid oxidation compounds) were higher in the doughs made with starches. The proportions of ethanol and 2/3-methylbutanol were higher in quinoa and amaranth crumbs whilst hexanal, 1-pentanol and 2,4-decadienal were higher in yellow and white corn crumbs.

Impact of environmental conditions and process modifications on microbial diversity, fermentation efficiency and chemical profile during the fermentation of Mezcal in Oaxaca

Mezcal, a distilled alcoholic beverage derived from cooked agave plants, is manufactured traditionally on a small scale where raw materials and production practices differ noticeably between production regions, localities and even factories resulting in a set of highly distinctive products. The present study aimed to draw a comprehensive picture of the mezcal production in Oaxaca State, relating the microbial consortia with the chemical compounds detected during mezcal fermentation, and to elucidate the impact of process modifications made in order to improve fermentation performance. In two mezcal distilleries, fermentation processes were monitored in two consecutive years. Isolated yeasts (553) and bacteria (527) were identified combining traditional and molecular techniques, detecting up to 21 different yeast species and 27 different bacterial species during a single process. Fermentation kinetics and volatile compound generation varied strongly between the studied processes. A highly diverse microbiota associated to these traditional alcoholic fermentations was detected wherein several yeast species and numerous bacterial groups built up the microbial consortia. Modifications introduced between two production seasons showed a clear impact on microbial diversity. The employment of wild inoculums increased alcoholic fermentation efficiency, nevertheless, prominent changes in the volatile compound profile should be taken into account.