Werner Grosch

Identification of the most intense volatile flavour compounds formed during autoxidation of linoleic acid

ZusammenfassungDie flüchtigen Verbindungen, die bei der Autoxidation von Linolsäure und Methyllinoleat bei 22–24 °C entstehen, wurden durch Capillar-Gaschromatographie und sensorische Beurteilung des Trägergasstromes analysiert. Die Anwendung des Verfahrens auf schrittweise verdünnte Extrakte ermöglichte die Bestimmung eines neuen Parameters, desD-Wertes, der die intensivsten Aromastoffe einer Probe anzeigt.Hexanal, 2(Z)-Octenal und 2(E)-Nonenal ergaben in beiden Lipiden die höchstenD-Werte. Bei Linolsäure folgte 1-Octen-3-ol und bei Methyllinoleat 1-Octen-3-on. Die Rangfolge der Aromastoffe war von der Autoxidationszeit abhängig. Nach 24stündiger Autoxidation von Linolsäure erschien 2(E)-Nonenal als stärkster Aromastoff. Nach 48 h ergaben dieser Aldehyd und Hexanal und nach 72 h Hexanal und 2(Z)-Octenal die höchstenD-Werte.Wie für 2(Z)-Octenal, 2(E)-Nonenal und 1-Octen-3-ol gezeigt, ist derD-Wert auch zur näherungsweisen Bestimmung von Geruchsschwellen geeignet.SummaryThe volatile compounds formed during autoxidation of linoleic acid and methyl linoleate at 22–24 °C were analysed by high resolution gas chromatography and eluate sniffing. The application of this technique to stepwise diluted extracts of the volatile compounds allowed the determination of a new parameter, theD-value, which reveals the most intense flavour compounds of an extract.Hexanal, 2(Z)-octenal and 2(E)-nonenal exhibited the highestD-values in both lipids. 1-Octen-3-ol followed in the case of linoleic acid and 1-octen-3-one in that of methyl linoleate. The grading of the flavour compounds was dependent on the autoxidation time. 2(E)-Nonenal was the most potent aroma compound up to 24 h of linoleic acid autoxidation. After 48 h aldehyde and hexanal and after 72 h hexanal and 2(Z)-octenal possessed the highestD-values. TheD-value can also be used for the approximation of odour threshold values as demonstrated for 2(Z)-octenal, 2(E)-nonenal and 1-octen-3-ol.

Potent odorants of the roasted powder and brew of Arabica coffee

ZusammenfassungDie Aromaextrakt-Verdünnungsanalyse (AEVA) von Röstkaffee ergab 13 wichtige Geruchsstoffe: 2-Methyl-3-furanthiol (I), 2-Furfurylthiol (II), Methional (III), 3-Mercapto-3-methylbutylformiat (IV), 3-Isopropyl-2-methoxypyrazin (V), 2-Ethyl-3,5-dimethylpyrazin (VI), 2,3-Diethyl-5-methylpyrazin (VII), 3-Isobutyl-2-methoxypyrazin (VIII), 3-Hydroxy-4,5-dimethyl-2(5H)-furanon (Sotolon, IX), 4-Vinylguajacol (XII) und (E)-β-Damascenon (XIII). Die vergleichende AEVA von Röstkaffee und daraus hergestelltem Aufguß zeigte im Aufguß eine Zunahme von III, IX, Vanillin und 4-Hydroxy-2,5-dimethyl-3(2H)-furanon und eine Abnahme von I, II, IV, V, VII und VIII.SummaryAroma extract dilution analysis (AEDA) revealed 13 compounds as important contributors to the aroma of roasted coffee (powder): 2-methyl-3-furanthiol (I), 2-furfurylthiol (II), methional (III), 3-mercapto-3-methylbutylformate (IV), 3-isopropyl-2-methoxypyrazine (V), 2-ethyl-3,5-dimethylpyrazine (VI), 2,3-diethyl-5-methylpyrazine (VII), 3-isobutyl-2-methoxy-pyrazine (VIII), 3-hydroxy-4,5-dimethyl-2(5H)-furanone (sotolon, IX), 4-ethylguaiacol (X), 5-ethyl-3-hydroxy-4-methyl-2(5H)-furanone (XI), 4-vinylguaiacol (XII), and (E)-β-damascenone (XIII). A comparative AEDA of the coffee powder and brew showed in the brew an increase of III, IX, vanillin and 4-hydroxy-2,5-dimethyl-3(2H)-furanone and a decrease of I, II, IV, V, VII, and VIII.

Fruits and Fruit Products

Fruits include both true fruits and spurious fruits, as well as seeds of cultivated and wild perennial plants. Fruits are commonly classified as pomaceous fruits, stone fruits, berries, tropical and subtropical fruits, hard-shelled dry fruits and wild fruits. The most important fruits are presented in Table 18.1 with pertinent data on botanical classification and use. Table 18.2 provides data about fruit production.

Cereals and Cereal Products

Cereal products are amongst the most important staple foods of mankind. Nutrients provided by bread consumption in industrial countries meet close to 50% of the daily requirement of carbohydrates, one third of the proteins and 50–60% of vitamin B. Moreover, cereal products are also a source of minerals and trace elements.

Evaluation of the flavour of wheat and rye bread crusts by aroma extract dilution analysis

ZusammenfassungDie neutral/basischen flüchtigen Verbindungen aus Weißbrot- and Roggenbrotkrusten wurden durch Capillar-Gaschromatographie, sensorische Beurteilung des Trägergasstromes and mit einer Verdünnungstechnik, die die intensivsten Geruchsstoffe anzeigt, analysiert. 2-Acetyl-l-pyrrolin (röstig, süß) dominierte im Weißbrotaroma, gefolgt vom 2(E)-Nonenal (grün, talgig) und 3-Methylbutanal (malzig). Im Aromagramm der Roggenbrotkruste, das bei der Verdünnungsanalyse erhalten wurde, kamen wesentlich mehr Aromastoffe vor. Besonders potente Geruchsstoffe waren 3-Methylbutanal, 2,6-Dimethyl-3-ethylpyrazin (kartoffelartig), 2(E)-Nonenal sowie eine Verbindung unbekannter Struktur mit getreideartig süßem Geruch.SummaryThe neutral and basic volatile compounds of wheat and rye bread crusts were analysed by high-resolution gas chromtography, effluent sniffing and by a dilution technique which revealed the most intense odour compounds. 2-Acetyl-l-pyrroline (roasted, sweet odour) predominated in the wheat bread aroma followed by 2(E)-nonenal (green, tallowy) and 3-methylbutanal (malty). More aroma compounds occurred in the aromagram obtained by the dilution analysis of the rye bread crusts. The most potent odour compounds found were: 3-methylbutanal, 2(E)nonenal, 2,6-dimethyl-3-ethylpyrazine (potato-like) and an unknown compound with a sweet, cereal-like odour.

Quantitation of potent odorants of virgin olive oil by stable-isotope dilution assays

The potent odorants of four olive oil samples differing in flavor were quantitated, and their odor activity values (OAVs) were calculated by dividing the concentrations of the odorants in the oil samples by the flavor threshold values in the oil. The odorants with higher OAVs were contrasted with the different notes of the flavor profiles of the olive oils. It was concluded that the following compounds contributed mainly to the flavor notes given in parentheses: (Z)-3-hexenal (green), ethyl 2-methylbutyrate, ethyl isobutyrate, ethyl cyclohexanoate (fruity), (Z)-2-nonenal (fatty) and 4-methoxy-2-methyl-2-butanethiol (black-currant-like). The results showed that the calculation of OAVs is an approach to objectify the flavor differences of olive oil samples.

The formation of 1-octen-3-ol from the 10-hydroperoxide isomer of linoleic acid by a hydroperoxide lyase in mushrooms (Psalliota bispora)

Abstract The 9-, 10-, 12- and 13-hydroperoxide isomers of linoleic acid were prepared by a photosensitized oxidation and then separated by HPLC. Each isomer was incubated with a protein fraction which had been isolated from a mushroom extract by precipitation with poly(ethylene glycol). The fraction reacted only with the 10-hydroperoxide isomer, which was cleaved to 1-octen-3-ol and 10-oxo- trans -8-decenoic acid.

Primary odorants of chicken broth

ZusammenfassungDurch Aromaextraktverdünnungsanalyse (AEVA) der flüchtigen Verbindungen, isoliert durch simultane Destillation/Extraktion aus Hühnerbrühe, wurden 16 primäre Aromastoffe mit FD-Faktoren im Bereich 64 bis 2048 wahrgenommen. Von diesen Verbindungen wurden 14 identifiziert: 2-Methyl-3-furanthiol, 2-Furfurylthiol, Methional, 2,4,5-Trimethylthiazol, Nonanal, 2(E)-Nonenal, 2-Formyl-5-methylthiophen,p-Kresol, 2(E),4(E)-Nonadienal, 2(E),4(E)-Decadienal, 2-Undecenal,β-Ionon, γ-Decalacton, γ-Dodecalacton. Die primären Geruchsstoffe der Hühnerbrühe wurden mit denen verglichen, die aus einer AEVA von Kuh- und Ochsenfleischbrühe stammten. Hauptunterschiede waren: 2(E),4(E)-Decadienal (fettig) und γ-Dodecalacton (talgig, fruchtig) überwogen in Hühnerbrühe, während die Schwefelverbindungen Bis(2-methyl-3-furyl)disulfid (fleischartig) und Methional (gekochte Kartoffeln) in den Brühen aus Rindfleisch dominierten. Die Geruchsschwellen (in Luft) wichtiger Fleischaromastoffe wurden bestimmt.SummaryAroma extract dilution analysis (AEDA) of the volatiles obtained by the simultaneous distillation/extraction of a chicken broth resulted in 16 primary odour compounds with FD factor values between 64 and 2048. Fourteen of these compounds were identified as: 2-methyl-3-furanthiol, 2-furfurylthiol, methional, 2,4,5-trimethylthiazole, nonanal, 2(E)-nonenal, 2-formyl-5-methylthiophene,p-cresol, 2(E),4(E)-nonadienal, 2(E),4(E)-decadienal, 2-undecenal,β-ionone, γ-decalactone and γ-dodecalactone. The primary odorants of chicken broth were compared with those resulting from the AEDA of broths from cow and ox meat. The major differences were that 2(E),4(E)-decadienal (fatty) and γ-dodecalactone (tallowy, fruity) prevailed in the chicken broth, whereas the sulphur compounds, bis(2-methyl-3-furyl)disulphide (meat-like-aroma) and methional (aroma like cooked potatoes), predominated in broths prepared from cow and ox meats. The odour thresholds (in air) of important meat aroma compounds are reported.

Evaluation of potent odorants in roasted beef by aroma extract dilution analysis

ZusammenfassungDie Aromaextrakt-Verdünnungsanalyse von gekochtem Rindfleisch ergab 25 Geruchsstoffe, von denen 22 identifiziert wurden. Die röstigen, caramelartigen, brenzlig und erdigen Geruchsnoten im Aroma wurden vom 2-Acetyl-2-thiazolin, Furaneol, Guajacol, 2-Ethyl-3,5-dimethylpyrazin und 2,3-Diethyl-5-methylpyrazin verursacht. (E)-2-Nonenal, (E,E)-2,4-Decadienal und γ-Octalacton stammten zumindest zum Teil vom zum Braten verwendeten Fett.SummaryAroma extract dilution analysis of the volatile fraction isolated from roasted beef resulted in 25 odour compounds of which 22 were identified. 2-Acetyl-2-thiazoline, furaneol, guaiacol, 2-ethyl-3,5-dimethylpyrazine and 2,3-diethyl-5-methylpyrazine were detected as the character impact compounds for the roasty, caramel-like, burnt and earthy odour notes. (E)-2-Nonenal, (E,E)-2,4-decadienal and γ-octalactone originated, at least in part, from the fat used for the roasting the meat.

Intensive neutral odourants of linden honey Differences from honeys of other botanical origin

ZusammenfassungDie Aromaextrakt-Verdünnungs-analyse der flüchtigen Verbindungen aus Lindenhonig ergab 21 Geruchsstoffe mit hohen FD-Faktoren; 18 davon wurden identifiziert: l-Hexen-3-on, 2-Acetyl-1 -pyrrolin, Dimethyltrisulfid, Methional, Phenylacetaldehyd, 2-Phenylethanol, Linalool, p-Kresol, 3,9-Epoxy-1 p-menthen, 4-Methylacetophenon, 3,9-Epoxy-1,4(8)p-menthadien (Lindenether), 1,3 -p-Menthadi-en-7-al,p-Anisaldehyd, 4-Vinylguajacol, (E)-β-Da-mascenon, Eugenol, Vanillin undcis-Rosenoxid. Lindenether undcis-Rosenoxid, die auch in einem Extrakt von Lindenblüten (Tilla cordata) vorkamen, fehlten in Honigen anderer botanischer Herkunft. Diese beiden Aromastoffe und das geruchlosetrans-Limonen-1,2-diol werden als Indikatoren für Linden honig vorgeschlagen. Die Geruchsschwellen (in Luft) der 18 Aromastoffe wurden bestimmt.SummaryAroma extract dilution analysis of linden honey volatiles resulted in 21 odour compounds having high factors of dilution (FD); 18 of these compounds were identified as 1-hexen-3-one, 2-acetyl-1 -pyrroline, dimethyl trisulphide, methional, phenylacetaldehyde, 2-phenylethanol, linalool, p-cresol, 3,9-epoxy-lpmenthene, 4-methylacetophenone, 3,9-epoxy-1,4(8)-p-menthadiene (linden ether), 1,3 p-menthadien-7-al, p-anisaldehyde, 4vinylguaiacol, (E)-p-damascenone, eugenol, vanillin andcis-rose oxide. Linden ether andcis-rose oxide, which were also found in an extract obtained from the blossoms of the lime tree (Tifa cordata), were absent in honeys of other botanical origin. These two odourants and the odourlesstrans-limonene-1,2-diol are proposed as indicators for linden honey. The odour thresholds (in air) of the 18 aroma compounds are reported.