U.S. Dept. of Agriculture, Agricultural Research Service, and North Carolina Agricultural Research Service, Dept. of Food, Bioprocessing and Nutrition Sciences, NC State Univ., Raleigh, NC 27695-7624, USA.
J Food Sci. 2011 Jan-Feb;76(1):C168-77. doi: 10.1111/j.1750-3841.2010.01918.x. Epub 2010 Nov 29.
A nontargeted, comprehensive 2-dimensional gas chromatography-time-of-flight mass spectrometry (GC×GC-TOFMS) method was developed for the analysis of fermented cucumber volatiles before and after anaerobic spoilage. Volatile compounds extracted by solid-phase microextraction were separated on a polyethylene glycol 1st-dimension column and 14% cyanopropylphenyl 2nd-dimension column. Among 314 components detected in fermented cucumber brine, 199 had peak areas with coefficients of variation below 30%. Peak identifications established by mass spectral library matching were 92% accurate based on 63 authentic standards. Analysis of variance of analytes' log peak areas revealed 33 metabolites changed in concentration after spoilage (P < 0.05), including increases in acetic, propanoic, and butyric acids, n-propyl acetate, several alcohols, and a decrease in furfural. GC×GC-TOFMS with a nontargeted, semi-automated approach to data analysis made possible the separation, identification, and determination of differences in polar volatile components, facilitating the discovery of several metabolites related to fermented cucumber spoilage. Practical Application: An optimized method for the chemical analysis of volatile food components is described and applied to the profiling of volatile compounds in fermented cucumbers, resulting in the identification of 137 components, many of which are being reported for the first time in fermented cucumbers. This nontargeted GC×GC-TOFMS method and inclusive data analysis platform facilitated the discovery of several metabolites that were formed or utilized during anaerobic spoilage of fermented cucumbers. Further study of these metabolites will enhance our ability to understand and potentially control the metabolism of spoilage bacteria that can degrade lactic acid under the restrictive environmental conditions present in fermented cucumbers.
建立了一种非靶向、全面的二维气相色谱-飞行时间质谱（GC×GC-TOFMS）方法，用于分析厌氧腐败前后发酵黄瓜中的挥发性物质。采用固相微萃取提取挥发性化合物，在聚乙二醇一维柱和 14%氰丙基苯基二维柱上进行分离。在发酵黄瓜卤水中检测到的 314 种成分中，有 199 种成分的峰面积变异系数低于 30%。通过质量光谱库匹配进行峰鉴定，基于 63 种纯标准品，鉴定准确率为 92%。对分析物对数峰面积的方差分析显示，33 种代谢物的浓度在腐败后发生变化（P<0.05），包括乙酸、丙酸和丁酸、乙酸正丙酯、几种醇和糠醛的增加。采用非靶向、半自动化数据分析方法的 GC×GC-TOFMS 实现了极性挥发性成分的分离、鉴定和差异测定，有助于发现与发酵黄瓜腐败相关的几种代谢物。实际应用：描述了一种用于挥发性食品成分化学分析的优化方法，并将其应用于发酵黄瓜挥发性化合物的分析，鉴定出 137 种成分，其中许多成分是首次在发酵黄瓜中报道的。这种非靶向 GC×GC-TOFMS 方法和包容性数据分析平台有助于发现几种代谢物，这些代谢物是在发酵黄瓜的厌氧腐败过程中形成或利用的。进一步研究这些代谢物将提高我们理解和潜在控制在发酵黄瓜中受限制的环境条件下可降解乳酸的腐败细菌代谢的能力。
