Department of Food Science and Technology, Food Chemistry Laboratory, BOKU-University of Natural Resources and Life Sciences Vienna, Muthgasse 11, A-1190 Vienna Austria.
J Chromatogr B Analyt Technol Biomed Life Sci. 2011 May 15;879(17-18):1361-6. doi: 10.1016/j.jchromb.2011.02.005. Epub 2011 Mar 1.
The evolution of free amino acid (FAA) profiles intrinsic to on-lees aged white wines was determined by ultra performance liquid chromatography (UPLC™). On basis of the AccQ.Tag™ method as a commercialized amino acid analysis solution for HPLC, a new protocol for dedicated amino acid analysis using 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) for pre-column derivatization was established by method transfer onto UPLC™ conditions. Since AQC derivatives enable both fluorescence (AccQ.Tag™ method) and UV detection, the performed method transfer additionally included changing to a more versatile UV detection. Emphasizing enhanced performance of UPLC™, the newly established protocol facilitated rapid and reliable separations of 24 amino acids within 23 min, hence proved to be superior compared to the original HPLC protocol due to significant improvements in resolution and reduced runtime. Applying UV detection enabled adequate quantifications of AQC amino acid derivatives at μM level (LOQs from 0.12 to 1.10 μM), thus proved sufficient sensitivity for amino acid profiling in wine samples. Moreover, this compiled methodology was successfully applied to monitor the changes of FAA concentrations in four distinct sets of on-lees aged white wines (fermented with different yeasts) at three progressing ripening periods, each (control, 3 and 6 months aging). For the control wines, the applied winery yeast significantly affected total FAA amounts (1450-1740 mg L(-1)). During maturation, the proceeding yeast autolysis implied a rather complex impact on FAAs, yielding total FAA excretions up to 360 mg L(-1). However, the magnitude for increases of specific FAAs (up to +200%) highly depended on the individual amino acids as well as on the applied fermenting yeast. Given the overall complexity of yeast autolysis in winemaking, the application of efficient LC techniques such as UPLC™ may indeed contribute as a valuable tool in wine research for product monitoring and characterization of intrinsic developments during wine maturation.
通过超高效液相色谱（UPLC™）确定了在瓶内陈酿白葡萄酒中固有游离氨基酸（FAA）谱的演变。基于 AccQ.Tag™方法作为 HPLC 的商业化氨基酸分析解决方案，通过方法转移到 UPLC™条件下，建立了一种用于专用氨基酸分析的新协议，该协议使用 6-氨基喹啉基-N-羟基琥珀酰亚胺基碳酸酯（AQC）进行柱前衍生。由于 AQC 衍生物可同时进行荧光（AccQ.Tag™方法）和紫外检测，因此进行的方法转移还包括更改为更通用的紫外检测。强调 UPLC™的增强性能，新建立的协议在 23 分钟内实现了 24 种氨基酸的快速可靠分离，因此与原始 HPLC 协议相比具有优越性，因为在分辨率和运行时间方面有显著提高。应用紫外检测能够在 μM 水平上对 AQC 氨基酸衍生物进行充分的定量（LOQ 为 0.12 至 1.10 μM），因此对于葡萄酒样品中的氨基酸分析具有足够的灵敏度。此外，该综合方法成功应用于监测在三个不同成熟阶段的四个不同组的瓶内陈酿白葡萄酒（用不同的酵母发酵）中 FAA 浓度的变化，每个阶段（对照，3 个月和 6 个月老化）。对于对照酒，应用的酿酒酵母显著影响总 FAA 量（1450-1740 mg L(-1)）。在成熟过程中，酵母自溶的进行对 FAAs 产生了相当复杂的影响，导致总 FAA 排泄量增加到 360 mg L(-1)。然而，特定 FAA 增加的幅度（高达+200%）高度取决于各个氨基酸以及应用的发酵酵母。鉴于酿酒过程中酵母自溶的整体复杂性，高效 LC 技术（如 UPLC™）的应用确实可以作为葡萄酒成熟过程中产品监测和内在发展特征的宝贵工具，应用于葡萄酒研究中。
