Cain Caitlin N, Haughn Noah J, Purcell Hayley J, Marney Luke C, Synovec Robert E, Thoumsin Chelsea T, Jackels Susan C, Skogerboe Kristen J
Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195, United States.
Department of Chemistry, Seattle University, 901 12th Avenue, Seattle, Washington 98122, United States.
J Agric Food Chem. 2021 Feb 24;69(7):2253-2261. doi: 10.1021/acs.jafc.1c00605. Epub 2021 Feb 10.
The quality of East African coffee beans has been significantly reduced by a flavor defect known as potato taste defect (PTD) due to the presence of 2-isopropyl-3-methoxypyrazine (IPMP) and 2-isobutyl-3-methoxypyrazine (IBMP). Therefore, the aims of this study were to determine the correlation between these methoxypyrazines and the severity of odor attributed to PTD and discover additional analytes that may be correlated with PTD using Fisher ratio analysis, a supervised discovery-based data analysis method. Specialty ground roasted coffees from East Africa were classified as clean (i.e., no off-odor), mild, medium, or strong PTD. For the samples examined, IPMP was found to discriminate between non-defective and defective samples, while IBMP did not do so. Samples affected by PTD exhibited a wide range of IPMP concentration (1.6-529.9 ng/g). Except for one sample, the IPMP concentration in defective samples was greater than the average IPMP concentration in the non-defective samples (2.0 ng/g). Also, an analysis of variance found that IPMP concentrations were significantly different based on the severity of odor attributed to PTD ( < 0.05). Fisher ratio analysis discovered 21 additional analytes whose concentrations were statistically different based on the severity of PTD odor ( < 0.05). Generally, analytes that were positively correlated with odor severity generally had unpleasant sensory descriptions, while analytes typically associated with desirable aromas were found to be negatively correlated with odor severity. These findings not only show that IPMP concentration can differentiate the severity of PTD but also that changes in the volatile analyte profile of coffee beans induced by PTD can contribute to odor severity.
由于存在2-异丙基-3-甲氧基吡嗪（IPMP）和2-异丁基-3-甲氧基吡嗪（IBMP），一种被称为马铃薯风味缺陷（PTD）的风味缺陷显著降低了东非咖啡豆的品质。因此，本研究的目的是确定这些甲氧基吡嗪与PTD所致气味严重程度之间的相关性，并使用基于监督发现的数据分析方法——费舍尔比率分析，发现可能与PTD相关的其他分析物。来自东非的特色研磨烘焙咖啡被分类为干净（即无异味）、轻度、中度或重度PTD。对于所检测的样品，发现IPMP能够区分无缺陷和有缺陷的样品，而IBMP则不能。受PTD影响的样品表现出广泛的IPMP浓度范围（1.6 - 529.9 ng/g）。除了一个样品外，有缺陷样品中的IPMP浓度高于无缺陷样品中的平均IPMP浓度（2.0 ng/g）。此外，方差分析发现，基于PTD所致气味的严重程度，IPMP浓度存在显著差异（<0.05）。费舍尔比率分析发现了另外21种分析物，其浓度根据PTD气味的严重程度存在统计学差异（<0.05）。一般来说，与气味严重程度呈正相关的分析物通常具有不愉快的感官描述，而通常与理想香气相关的分析物则与气味严重程度呈负相关。这些发现不仅表明IPMP浓度可以区分PTD的严重程度，还表明PTD引起的咖啡豆挥发性分析物谱的变化可能导致气味严重程度增加。
