Pollner Gwendola, Schieberle Peter
Deutsche Forschungsanstalt für Lebensmittelchemie - Leibniz Institut , Lise-Meitner-Straße 34, D-85354 Freising, Germany.
J Agric Food Chem. 2016 Jan 27;64(3):627-36. doi: 10.1021/acs.jafc.5b05321. Epub 2016 Jan 13.
By application of aroma extract dilution analysis (AEDA) on the volatile fraction isolated from commercial cold-pressed rapeseed oil prepared from unpeeled seeds, 35 odor-active constituents in the flavor dilution (FD) factor range of 8-8192 were detected. The identification experiments showed that the earthy, pea-like-smelling 2-isopropyl-3-methoxypyrazine showed the highest FD factor of 8192, followed by 1-octene-3-one (FD 4096) and (E,Z)-2,6-nonadienal with an FD of 2048. After quantitation of the 16 key odorants showing FD factors ≥32 by stable isotope dilution assays and a determination of their odor thresholds in deodorized sunflower oil, odor activity values (OAV; ratio of concentration to odor threshold) could be calculated. The results indicated 2-isopropyl-3-methoxypyrazine, (E,E)-2,4-nonadienal (deep-fried, fatty), and (E,Z)-2,6-nonadienal (cucumber-like) with the highest OAVs. To confirm that the key aroma compounds were correctly identified and quantitated, a recombination experiment was performed by mixing the reference odorants in the same concentrations as they occurred in the rapeseed oil using odorless sunflower oil as the matrix. The recombinate showed a very good agreement with the overall aroma of the oil. In a commercial rapeseed oil prepared from peeled seeds, the same odorants were identified; however, in particular, the FD factor of dimethyl sulfide (DMS) was clearly higher. Quantitation of DMS in 10 commercial rapeseed oils from either peeled and unpeeled seeds revealed significant differences in DMS, but no influence of the peeling process on the amounts of DMS was found. The data can serve as a basis for the quality assessment of cold-pressed rapeseed oil.
通过对从未去皮种子制备的市售冷榨菜籽油中分离出的挥发性成分进行香气提取物稀释分析(AEDA),检测到了35种风味稀释(FD)因子在8 - 8192范围内的气味活性成分。鉴定实验表明,具有泥土味、豌豆样气味的2 - 异丙基 - 3 - 甲氧基吡嗪显示出最高的FD因子8192,其次是1 - 辛烯 - 3 - 酮(FD 4096)和(E,Z)- 2,6 - 壬二烯醛,其FD为2048。通过稳定同位素稀释分析对16种FD因子≥32的关键气味物质进行定量,并测定它们在脱臭向日葵油中的气味阈值后,可计算出气味活性值(OAV;浓度与气味阈值之比)。结果表明,2 - 异丙基 - 3 - 甲氧基吡嗪、(E,E)- 2,4 - 壬二烯醛(油炸味、脂肪味)和(E,Z)- 2,6 - 壬二烯醛(黄瓜样)的OAV最高。为了确认关键香气化合物被正确鉴定和定量,使用无味向日葵油作为基质,将参考气味物质以与它们在菜籽油中出现的相同浓度混合进行重组实验。重组物与油的整体香气显示出非常好的一致性。在由去皮种子制备的市售菜籽油中,鉴定出了相同的气味物质;然而,特别是二甲基硫醚(DMS)的FD因子明显更高。对10种来自去皮和未去皮种子的市售菜籽油中的DMS进行定量分析发现,DMS存在显著差异,但未发现去皮过程对DMS含量有影响。这些数据可作为冷榨菜籽油质量评估的基础。