ABSTRACT
With the aim of determining the formation of alpha-dicarbonyl intermediates during beer aging on the shelf, alpha-dicarbonyls were identified and quantified after derivatization with 1,2-diaminobenze to generate quinoxalines. The sensory effects of alpha-dicarbonyls were evaluated by the quantification of key Strecker aldehydes and by GC-olfactometry (GCO)analysis of beer headspace using solid phase microextraction. Four alpha-dicarbonyls, reported here for the first time, were detected in fresh and aged beers, three were derived from the 2,3-enolization pathway of mono- and disaccharides, and the fourth was derived from the epimerization of 3-deoxy-2-hexosulose. Ten alpha-dicarbonyls were quantified during beer processing and during different periods of beer aging at 28 degrees C. The aging periods were from 15 to 105 days. During beer aging, 1-deoxydiuloses were produced and degraded, while 1,4-dideoxydiuloses were produced at the highest rates. The GCO analysis indicated that forced beer aging increased the amounts of furaneol, trans-2-nonenal, and phenylacetaldehyde. The blockage of alpha-dicarbonyls inhibited the accumulation of sensory-active aldehydes in the beer headspace.
Subject(s)
Beer/analysis , Food Preservation , Acetaldehyde/analogs & derivatives , Acetaldehyde/analysis , Aldehydes/analysis , Chromatography, Gas , Deoxyglucose/analogs & derivatives , Deoxyglucose/analysis , Food Handling , Furans/analysis , Humans , Smell , Time FactorsABSTRACT
A chloroform extract from roots of Craniolaria annua provided six new C-11 unsubstituted abietanes, 14-hydroxy-6,12-dione-7,9(11),13-abietatriene (1), 14-hydroxy-12-oxo-7,9(11),13-abietatriene (2), 6,12,14-trihydroxyabieta-5,8,11,13-tetraen-7-one (3), ar-abietatriene-12-ol-6,7-dione-14,16-oxide (4), ar-abietatriene-12,16-diol-14,16-oxide (5) and ar-abietatriene-12-ol-7-one-14,16-oxide (6), and two known compounds, ferruginol and stigmasterol. The structures of both the new and known compounds were established by spectroscopic methods. Abietane 1 gave 14-hydroxy-6-oxoferruginol (1A) upon treatment with NaBH4. Abietanes 1, 1A, 3-5 and ferruginol showed cytotoxic effects against trypomastigote and epimastigote forms of Trypanosoma cruzi and against fibroblastic Vero cells.
