Tsachaki Maroussa, Linforth Robert S T, Taylor Andrew J
Samworth Flavour Laboratory, Division of Food Sciences, Sutton Bonington Campus, University of Nottingham, Loughborough LE12 5RD, United Kingdom.
J Agric Food Chem. 2009 Aug 12;57(15):6976-81. doi: 10.1021/jf901174y.
Aroma release from wines and model ethanolic solutions during dynamic headspace dilution was measured in real time using atmospheric pressure chemical ionization-mass spectrometry. Model ethanolic solutions maintained the headspace concentration of volatile compounds close to equilibrium values during gas phase dilution over 10 min. Wine samples (with the same ethanol content) did not maintain the headspace concentration of volatiles to the same extent. Wine components and acidity ((+)-catechin, glycerol; pH 3.6) in model ethanolic solutions (120 mL/L) had no effect on the volatile headspace concentration during dynamic headspace dilution. However, in the presence of certain proteins (beta-lactoglobulin, beta-casein, bovine serum albumin), the model ethanolic solutions failed to maintain their volatile headspace concentration upon headspace dilution, but other proteins (thaumatin, mucin, lysozyme) had no effect. Thermal imaging of the model ethanolic samples (with and without beta-casein) under dynamic headspace dilution conditions showed differences in surface temperatures. This observation suggested perturbation of the ethanol monolayer at the air-liquid interface and disruption of the Marangoni effect, which causes bulk convection within ethanolic solutions. Convection carries volatile compounds and warm liquid from the bulk phase to the air-liquid interface, thus replenishing the interfacial concentration and maintaining the gas phase concentration and interfacial surface temperature during headspace dilution. It is postulated that certain proteins may exert a similar effect in wine.
在动态顶空稀释过程中，使用大气压化学电离质谱实时测量葡萄酒和模拟乙醇溶液中的香气释放。在10分钟的气相稀释过程中，模拟乙醇溶液的挥发性化合物顶空浓度保持接近平衡值。葡萄酒样品（乙醇含量相同）在相同程度上未能保持挥发性物质的顶空浓度。模拟乙醇溶液（120 mL/L）中的葡萄酒成分和酸度（（+）-儿茶素、甘油；pH 3.6）在动态顶空稀释过程中对挥发性顶空浓度没有影响。然而，在存在某些蛋白质（β-乳球蛋白、β-酪蛋白、牛血清白蛋白）的情况下，模拟乙醇溶液在顶空稀释时未能保持其挥发性顶空浓度，但其他蛋白质（奇异果甜蛋白、粘蛋白、溶菌酶）没有影响。在动态顶空稀释条件下对模拟乙醇样品（有和没有β-酪蛋白）进行热成像显示表面温度存在差异。这一观察结果表明气液界面处乙醇单分子层受到扰动，马兰戈尼效应被破坏，马兰戈尼效应会导致乙醇溶液内部的整体对流。对流将挥发性化合物和温暖的液体从本体相输送到气液界面，从而在顶空稀释过程中补充界面浓度并维持气相浓度和界面表面温度。据推测，某些蛋白质在葡萄酒中可能会产生类似的影响。
