Influence of different flours and starches on gluten-free bread aroma.
ABSTRACT: 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.
Project description:This is the first study to reveal potential markers for volatile changes during ambient and accelerated shelf life of pasteurized apple juice. The volatile changes were monitored at 20, 30 and 40 °C using a headspace solid-phase microextraction-gas chromatography-mass spectrometry fingerprinting method. Using modern chemometrics and feature selection, hexanal, trans-2-hexenal, dimethyl sulphide, furfural, ethyl acetate and 1-pentanol were chosen as potential shelf life markers. Volatiles associated with the green, grassy and fresh apple aroma, such as hexanal and trans-2-hexenal, decreased during storage, whereas thermal load and browning associated compounds, like dimethyl sulphide and furfural, increased during storage. Hexanal and trans-2-hexenal can be markers to monitor the change in green-apple like character. Furfural and dimethyl sulphide can be markers of temperature abuse during juice processing and storage. Furfural can also be an indicator for juice browning. The present work effectively identified potential markers to monitor and predict volatile aroma changes of shelf stable apple juice in different storage conditions. Sensory analysis can be conducted in the future to confirm the aroma relevance of selected markers.
Project description:<h4>Purpose</h4>The volatile compounds that contribute to the flavor of pork are unknown. Therefore, the present study aimed to determine the differences in volatile compounds from pork meats of four different pig breeds using headspace solid-phase micro-extraction (HS-SPME)/gas chromatography-mass spectrometry (GC-MS).<h4>Methods</h4>Piglets from four breeds (8/breed) (crossbred Ziwuling <i>Sus scrofa</i> [SUS] and purebreds Bamei pig [BAM], American Yorkshire pig [YOK], and Hezuo pig [HZP]) were selected. Characteristics of meat were measured. HS-SPME/GC-MS were used to analyze the volatile compounds of the meats.<h4>Results</h4>The tenderness, taste, succulence, and broth flavor of the BAM and HZP were good. One hundred and eight volatile compounds with known molecular formulas were identified in BAM, 106 in SUS, 98 in YOK, and 98 in HZP. Sixty-four common volatile compounds were found in all four breeds. The highest relative amount of volatile compounds was found in the BAM. The compounds which may contribute to the flavor of pork were 3-methyl-1-butanol, 1-nonanal, octanal, hexanal, 2-pentyl-furan, 1-penten-3-one, N-morpholinomethyl-isopropyl-sulfide, methyl butyrate, and (E,E)-2, 4-decadienal.<h4>Conclusion</h4>The volatile compounds in pork belong to several classes, and the highest relative amount of volatile compounds was found in BAM.
Project description:Superheated steam was used to cook barley and the volatile odor compounds and release of odorants from the steamed barley were analyzed. The main odor compounds in cooked barley were aldehydes (hexanal and (E,E)-2,4-decadienal) and acids (acetic acid and hexanoic acid). Compared to ordinary cooked barley, barley cooked by superheated steam had less odorants, and the release of odorants was reduced by almost half. Sensory evaluation revealed that this barley was preferred to ordinary cooked barley, because it had weaker smell and tasted less sour and less bitter. The steaming process steam distils and eliminates some odor compounds, while some water-soluble compounds (mainly acids) are washed away by water during steaming. Therefore, this steam cooking method, applied to barley for the first time here using a comprehensive analysis, improves the acceptability and palatability of this high-quality food rich in dietary fiber.
Project description:Volatile compounds are the major determinants of aroma and flavor in both grapes and wine. In this study, we investigated the emission of volatile and non-volatile compounds during berry maturation in two grape varieties (Airén and Tempranillo) throughout 2010 and 2011. HS-SPME coupled to gas chromatography and mass spectrometry was applied for the identification and relative quantitation of these compounds. Principal component analysis was performed to search for variability between the two cultivars and evolution during 10 developmental stages. Results showed that there are distinct differences in volatile compounds between cultivars throughout fruit development. Early stages were characterized in both cultivars by higher levels of some apocarotenoids such as ?-cyclocitral or ?-ionone, terpenoids (E)-linalool oxide and (Z)-linalool oxide and several furans, while the final stages were characterized by the highest amounts of ethanol, benzenoid phenylacetaldehyde and 2-phenylethanol, branched-amino acid-derived 3-methylbutanol and 2-methylbutanol, and a large number of lipid derivatives. Additionally, we measured the levels of the different classes of volatile precursors by using liquid chromatography coupled to high resolution mass spectrometry. In both varieties, higher levels of carotenoid compounds were detected in the earlier stages, zeaxanthin and ?-carotene were only detected in Airén while neoxanthin was found only in Tempranillo; more variable trends were observed in the case of the other volatile precursors. Furthermore, we monitored the expression of homolog genes of a set of transcripts potentially involved in the biosynthesis of these metabolites, such as some glycosyl hydrolases family 1, lipoxygenases, alcohol dehydrogenases hydroperoxide lyases, O-methyltransferases and carotenoid cleavage dioxygenases during the defined developmental stages. Finally, based on Pearson correlation analyses, we explored the metabolite-metabolite fluctuations within VOCs/precursors during the berry development; as well as tentatively linking the formation of some metabolites detected to the expression of some of these genes. Our data showed that the two varieties displayed a very different pattern of relationships regarding the precursor/volatile metabolite-metabolite fluctuations, being the lipid and the carotenoid metabolism the most distinctive between the two varieties. Correlation analysis showed a higher degree of overall correlation in precursor/volatile metabolite-metabolite levels in Airén, confirming the enriched aroma bouquet characteristic of the white varieties.
Project description:Jujube (<i>Ziziphus jujuba</i> Mill.) extract has been commonly used as a flavoring ingredient due to its unique aroma. In this study, solid phase micro extraction method was used to extract the volatile compounds in fresh jujube, with the aid of GC-MS for further chemical separation and identification. As a result, 33 volatile compounds, including aldehydes, alcohols, acids, ketones and esters, were identified. Among them, hexanal (276.5-1314 ?g/100 g FW), (<i>E</i>)-2-hexanal, (145.1-1876 ?g/100 g FW), nonanal (188.2-1047 ?g/100 g FW), and n-decanoic acid (58.42-1268 ?g/100 g FW) were found to be the major volatile compounds in fresh jujube fruit. Based on the type and amounts of the volatile compounds, 15 Chinese jujube cultivars were divided into 5 clusters through hierarchical cluster analysis and principal component analysis (PCA). Fiver clusters include cluster 1 (LB, HP, LZ, NP, JS, PZ, and YL), cluster 2 (BJ, DB), cluster 3 (PB, BZ, JD and XZ), cluster 4 (JB) and cluster 5 (YZ). According to the PCA, the clusters 1, 2 and 3 could not be discriminated from each other, but clusters 4 and 5 could be separated very well from each other.
Project description:The volatile components of milks fermented using traditional starter cultures (Streptococcus thermophilus and Lactobacillus bulgaricus) and probiotics (Lactobacillus lactis, Lactobacillus bifidus, Lactobacillus casei, and Lactobacillus plantarum) were investigated by means of gas chromatography-mass spectrometry (GC-MS) combined with simultaneous distillation extraction (SDE). A total of 53 volatile compounds were detected, being 10 aldehydes, 11 ketones, 10 acids, 11 hydrocarbons, 7 benzene derivatives, and 4 other compounds. The starter culture was found to significantly affect the composition of volatile components in the fermented milks. Ketones and hydrocarbons were the dominant compounds in milk before fermentation, while acids were dominant compounds in the fermented samples. Compared with probiotics, there was greater abundance of volatile components in fermented milks with traditional strains. The importance of each volatile compound was assessed on the basis of odor, thresholds, and odor activity values (OAVs). Of the volatile compounds, 31 of them were found to be odor-active compounds (OAV > 1). The component with the highest OAVs in most samples was (E,E)-2,4-decadienal. Heatmap analysis and principal component analysis were employed to characterize the volatile profiles of milks fermented by different starter cultures. The results could help to better understand the influence of starter cultures on the odor quality of milks.
Project description:Nitrogen (N) is an important macronutrient for plant growth and development, but the regulatory mechanism of volatile compounds in response to N deficiency is not well understood, especially in cucumber, which consumes excessive N during growth. In this study, the major volatile compounds from cucumber leaves subjected to N deficiency were analyzed by GC-MS. A total of 24 volatile components were identified including 15 aldehydes, two ketones, two alkenes, and five other volatile compounds in 9930 leaves. Principal component analysis using volatile compounds from cucumber leaves provided good separation between N-sufficient and N-deficient treatments. The main volatiles in cucumber leaves were found to be C6 and C9 aldehydes, especially (<i>E</i>)-2-hexanal and (<i>E</i>,<i>Z</i>)-2,6-nonadienal. (<i>E</i>)-2-hexanal belonged to the C6 aldehyde and was the most abundant compound, whereas (<i>E</i>,<i>Z</i>)-2,6-nonadienal was the chief component of C9 aldehydes. During N-deficient treatment, short-chain volatile content was significantly improved at 5 day, other volatiles displayed significant reduction or no significantly changes in all sampling points. Improvement of short-chain volatiles was confirmed in the six other inbred lines at 5 day after N-deficient treatments. The expression analysis of 12 cucumber <i>LOX</i> genes and two <i>HPL</i> genes revealed that <i>CsLOX19</i>, <i>CsLOX20</i>, and <i>CsLOX22</i> had common up-regulated expression patterns in response to N-deficient stress in most inbred lines; meanwhile, most sample points of <i>CsHPL1</i> also had significant up-regulated expression patterns. This research focused on the relationship between volatiles in cucumber and different nitrogen environments to provide valuable insight into the effect of cultivation and management of the quality of cucumber and contributes to further research on volatile metabolism in cucumber.
Project description:A cross-reactive array of polycyclic aromatic hydrocarbons and single wall carbon nanotube bilayers was designed for the detection of volatile organic compounds (tentatively, hexanal and 5-methyl-undecane) that identify the presence of disease in the exhaled breath of patients with multiple sclerosis. The sensors showed excellent discrimination between hexanal, 5-methyl-undecane, and other confounding volatile organic compounds. Results obtained from a clinical study consisting of 51 volunteers showed that the sensors could discriminate between multiple sclerosis and healthy states from exhaled breath samples with 85.3% sensitivity, 70.6% specificity, and 80.4% accuracy. These results open new frontiers in the development of a fast, noninvasive, and inexpensive medical diagnostic tool for the detection and identification of multiple sclerosis. The results could serve also as a launching pad for the discrimination between different subphases or stages of multiple sclerosis as well as for the identification of multiple sclerosis patients who would respond well to immunotherapy.
Project description:Volatile compounds in flowers of Rhododendron delavayi, R. agastum, R. annae, and R. irroratum were analyzed using comprehensive two-dimensional gas chromatography-mass spectrometry (GC×GC) coupled with high-resolution quadrupole time-of-flight mass spectrometry (QTOFMS). A significantly increased number of compounds was separated by GC×GC compared to conventional one-dimensional GC (1DGC), allowing more comprehensive understanding of the volatile composition of Rhododendron flowers. In total, 129 volatile compounds were detected and quantified. Among them, hexanal, limonene, benzeneacetaldehyde, 2-nonen-1-ol, phenylethyl alcohol, citronellal, isopulegol, 3,5-dimethoxytoluene, and pyridine are the main compounds with different content levels in all flower samples. 1,2,3-trimethoxy-5-methyl-benzene exhibits significantly higher content in R. irroratum compared to in the other three species, while isopulegol is only found in R. irroratum and R. agastum.
Project description:Three varieties of safflower seed oil (SSO) from Xinjiang Autonomous Region, China, were analyzed by headspace solid-phase micro-extraction gas chromatography coupled with mass spectrometry (HS-SPME-GC-MS) to reveal volatile components. Overall, 67 volatile components were determined and four compounds including isoamyl alcohol, caproic acid, n-pentanal, and heptanal were newly identified in SSO as aroma-active components. Meanwhile, 16 compounds were selected by relative odor activity value (ROAV) to evaluate contributions of single compounds to the overall odor (ROAV > 1), in which nonanal, (Z)-6-nonenal, and (E)-2,4-decadienal were the top three contributed substances (ROAV > 70). The sensory panel was described as eight definition terms (grassy, fruity, almond, mushroom, fatty, sweet, paddy, and overall fragrance). Principal component analysis (PCA) revealed a significant separation of three cultivars with the first principal component (PC-1) and the second principal component (PC-2) expressing 73.9% and 23.1%, respectively. Both PCA and ROAV allowed identifying the compounds positively correlated to sensory evaluation.