1,721,024 research outputs found
Wild Harenna coffee: flavour profiling from the bean to the cup
Full text linkAs one of the last places where coffee grows spontaneously, the Harenna forest (Ethiopia) is the origin of the coffee analysed in this study. The analysis of the volatile emission of each processing phase evaluates the chemical fingerprint of the reactions taking place at each stage, leading to the final aroma. The green beans mainly emit non-terpene esters and alkanes. Once the roasting begins, monoterpenes are the main class until 160 °C: at this point, 2,6-dimethylpyrazine prevails in the headspaces, as main product of the Maillard reactions. This compound, with its sweet and nut-like aroma, is also detected in the brewed coffee. The shed silverskins are rich in methyl chavicol and retain the monoterpenes on the beans: as these compounds are important aroma contributors, the removal of the silverskins prior to roasting seems non-advisable. The grinding of the samples breaks the matrices and leads to drastic changes in the volatile emissions
Essential oil composition of Terminalia ivorensis A. Chev. flowers from Northern Nigeria
Full text linkIn the present study, the volatile compounds identified in the essential oil from the flowers of Terminalia ivorensis A. Chev (Combretaceae) collected from Kaduna, Northern Nigeria, are reported. Essential oils were obtained using hydrodistllation in a Clevenger- type apparatus. The yield of the light yellow oil was found to be 0.22% (v/w, dry weight basis). The content and composition of the oil were analyzed by gas chromatography (GC-FID) and gas chromatography with electron impact mass spectrometry (GC-MS). The main compounds of the oil were δ-3-carene (29.4%) and α-pinene (20.9%). To the best of our knowledge, this is the first report on the essential oil constituents of any part of T. ivorensis
Characterization of volatile metabolites of Tithonia diversifolia(Hemsley) A. gray leaves and flowers
No full textThe leaf and floral essential oils of Tithonia diversifolia (Hemsley) A. Gray (Asteraceae) were analyzed for composition by means of gas chromatography-mass spectrometry (GC-MS). Forty-two constituents were identified in the leaf and floral oils, accounting for 97.2% and 95.3% of the total composition, respectively. Germacrene D (46.0%), β-caryophyllene (12.2%), and methyl carvacrol (9.8%) were the prominent components of the leaf oil, while the main constituents of the floral oil consisted of germacrene D (32.5%), α-pinene (7.5%), and β-caryophyllene (6.6%
Aroma evolution in chocolate production
No full textChocolate aroma development, indeed, depends on several factors. Several volatile organic compound (VOC) chemical classes contribute to the distinctive chocolate aroma: most develop from aroma precursors, namely reducing sugars and free amino acids, whose production is thermally induced once the fermentation begins and the enzyme pools are triggered. Over 600 VOCs have been reported in the chocolate headspace, of which pyrazines are the most important compounds involved in its distinctive flavor, with a detected pool of circa 80 different molecules belonging to this class. Methyl-, ethyl-esters, and acetates are the most involved VOCs of this chemical class of compounds in chocolate headspace emission. Some derivatives, instead, exhibit an undesirable contribution to the overall chocolate flavor perception: 2-, 3-, and 4-methylphenols have a medicinal and unpleasant aroma, as well as 2-butanol. The drying phase is also important in chocolate aroma evolution, as it is also meant to improve flavor development
Comparison of the chemical and sensorial evaluation of dark chocolate bars
No full textAs it mimics olfactory perception, headspace analysis is frequently used for examination of products like chocolate, in which aroma is a key feature. Chemical analysis by itself, however, only provides half the picture, as final consumer’s perception cannot be compared to that of a Gas Chromatography-Mass Spectrometry (GC-MS) port, but rather to a panel test assessment. The aim of the present study was the evaluation of combined chemical (by means of headspace solid-phase microextraction and GC-MS) and panel test data (by means of a sensory evaluation operated by 6 untrained panelists) obtained for 24 dark chocolate bars to assess whether these can discriminate between bars from different brands belonging to different commercial segments (hard discount, HD; supermarket, SM; organic bars, BIO). In all samples, with the only exception of one supermarket bar (in which esters exhibited the highest relative abundance), pyrazines were detected as the most abundant chemical class (HD: 56.3–74.2%; BIO: 52.0–76.4%; SM: 31.2–88.9%). Non-terpene alcohols, aldehydes, and esters followed as quantitatively relevant groups of compounds. The obtained data was then subjected to hierarchical cluster (HCA) and principal component (PCA) analysis. The statistical distribution of samples obtained for the chemical data did not match that obtained with panelists’ sensorial data. Moreover, although an overall ability of grouping samples of the same commercial origin was evidenced for hard discount and supermarket bars, no sharp grouping was possible
Contribution to the study of the chemical variability of the essential oils of the seeds and the stems in some populations of Pituranthos tortuosus (Coss.) Maire from Tunisia
No full textPurpose The aim of this study was to investigate the variation of the chemical composition of the seeds and stems essential oils of Pituranthos tortuosus (Coss.) Maire collected from three regions of Tunisia (Bousaid (Sfax), Rgeb (Sidi Bouzid) and Majoura (Gafsa)). Method The seeds and the stems were hydrodistillated during 4 h by using a Clevenger-type apparatus. The obtained essential oils were analyzed by GC and GC-EI-MS. Results The chromatographic analysis indicated the detection of sixty-seven components accounting from 97.5% to 99.7% of the whole of each essential oil with a predominance of monoterpene hydrocarbons (from 38.2% to 66.1%). So, a strong predominance of the monoterpene fraction was observed in the seeds (75.8%; 60.6%; 90.8%) and the stems (89.7%; 91.7%; 89.7%) essential oil of P. tortuosus collected from Majoura, Bousaid and Rgeb, respectively. However, sabinene (19.4%; 11.8%; 24.7%) and terpinen-4-ol (16.9%; 22.9%; 19.2%) were the most abundant compounds of the essential oil of seeds and stems of Rgeb as well as the essential oil of the stems of Majoura, respectively, whereas the major components of the seeds of P. tortuosus collected from Majoura were limonene (25.1%), sabinene (18.6%) and apiol (13.4%). The stems essential oils of Bousaid were dominated by terpinen-4-ol (32.3%), sabinene (23.6%) and p-cymene (10.9%) while dillapiole (34.7%), limonene (14.3%), sabinene (12.6%) and terpinen-4-ol (10.4%) were the main components of the essential oil of the seeds collected from Bousaid. Conclusion Based on the main compounds, the essential oils of seeds and stems of P. tortuosus from the three regions of Tunisia displayed different chemical compositions
Dal seme di cacao alla tavoletta: variazioni del profilo aromatico volatile nella filiera produttiva del ‘Blanco de Criollo’
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