Impact of Malt Extract Addition on Odorants in Wheat Bread Crust and Crumb.

Application of gas chromatography-olfactometry and aroma extract dilution analysis to the volatiles isolated from (1) crust and (2) crumb of a wheat bread made with the addition of a dark liquid malt extract (LME) to the dough and (3) crust and (4) crumb of a reference bread made without addition resulted in the identification of 23 major odorants. Their quantitation followed by the calculation of odor activity values (OAV = ratio of concentration to odor threshold value) suggested that LME addition influenced the aroma of the bread predominantly by increasing seasoning-like smelling sotolon in crust and crumb, and caramel-like smelling compounds maltol and 4-hydroxy-2,5-dimethylfuran-3(2H)-one (HDMF) in the crumb. The increase in sotolon and maltol was explainable by direct transfer from the LME to the bread, whereas HDMF must have been formed from LME-derived precursors. This difference needs to be considered in the targeted optimization of LMEs for bread making.

New Degradation Pathways of the Key Aroma Compound 1-Penten-3-one during Storage of Not-from-Concentrate Orange Juice.

1-Penten-3-one with its fresh and pungent smell at a very low odor threshold of 0.94 µg/L water has been characterized as impact aroma compound in many foods, such as grapefruit, orange juice, black tea, olive oil, or tomatoes. While its importance to the fresh sensation of unstored not-from-concentrate (NFC) orange juice was recently confirmed by aroma recombinates, a total loss was determined already after 4 weeks in NFC orange juice stored at 0 °C. Until now, the degradation pathway of this compound has not been clarified. Systematic model studies resulted in the identification of 1-hydroxy-3-pentanone and 4-hydroxy-3,8-decanedione as degradation products as well as S-(3-oxopentyl)-l-cysteine in the presence of the amino acid. In orange juice samples, it was found that the elevated content of 1-hydroxy-3-pentanone indicates a thermal processing, while S-(3-oxopentyl)-l-cysteine showed a significant increase during cold storage. Additionally, both compounds were identified in other food samples, such as commercial orange juices, pickled olives and olive oil, fresh tomatoes and commercial tomato juice, and black tea.

Characterization of Key Aroma Compounds in Raw and Thermally Processed Prawns and Thermally Processed Lobsters by Application of Aroma Extract Dilution Analysis.

Application of aroma extract dilution analysis (AEDA) to an aroma distillate of blanched prawn meat (Litopenaeus vannamei) (BPM) revealed 40 odorants in the flavor dilution (FD) factor range from 4 to 1024. The highest FD factors were assigned to 2-acetyl-1-pyrroline, 3-(methylthio)propanal, (Z)-1,5-octadien-3-one, trans-4,5-epoxy-(E)-2-decenal, (E)-3-heptenoic acid, and 2-aminoacetophenone. To understand the influence of different processing conditions on odorant formation, fried prawn meat was investigated by means of AEDA in the same way, revealing 31 odorants with FD factors between 4 and 2048. Also, the highest FD factors were determined for 2-acetyl-1-pyrroline, 3-(methylthio)propanal, and (Z)-1,5-octadien-3-one, followed by 4-hydroxy-2,5-dimethyl-3(2H)-furanone, (E)-3-heptenoic acid, and 2-aminoacetophenone. As a source of the typical marine, sea breeze-like odor attribute of the seafood, 2,4,6-tribromoanisole was identified in raw prawn meat as one of the contributors. Additionally, the aroma of blanched prawn meat was compared to that of blanched Norway and American lobster meat, respectively (Nephrops norvegicus and Homarus americanus). Identification experiments revealed the same set of odorants, however, with differing FD factors. In particular, 3-hydroxy-4,5-dimethyl-2(5H)-furanone was found as the key aroma compound in blanched Norway lobster, whereas American lobster contained 3-methylindole with a high FD factor.