Dept. of Physics and Control, Szent Istvan Univ., Budapest, Hungary.
Dept. of Oenology, Szent Istvan Univ., Budapest, Hungary.
J Food Sci. 2019 Dec;84(12):3437-3444. doi: 10.1111/1750-3841.14956. Epub 2019 Nov 24.
Tokaj wines (Hungaricum) are botrytized wines acknowledged for the unique organoleptic properties bestowed by botrytized grape berries during production. Excluding these berries during wine production or manipulating the sugar content of low-grade wines to imitate high-grade wines are some recent suspicious activities that threaten the wine quality. Advanced methods such as spectroscopy and sensor-based devices have been lauded for rapid, reliable, and cost-effective analysis, but there has been no report of their application to monitor grape must concentrate adulteration in botrytized wines. The study aimed to develop models to rapidly discriminate lower grade Tokaj wines, "Forditas I" and "Forditas II," that were artificially adulterated with grape must concentrate to match the sugar content of high-grade Tokaj wines using an electronic tongue (e-tongue) and two near infrared spectrometers (NIRS). Data were evaluated with the following chemometrics: principal component analysis (PCA), discriminant analysis (LDA), partial least square regression (PLSR), and aquaphotomics (a novel approach). There was a noticeable pattern of separation in PCA for all three instruments and 100% classification of adulterated and nonadulterated wines in LDA using the e-tongue. Aquagrams from the aquaphotomics approach showed important water absorption bands capable of being markers of Tokaj wine quality. PLSR models showed coefficient of determination (R CV) of 0.98 (e-tongue), 0.97 (benchtop NIRS), 0.87 (handheld NIRS), and low root mean squared errors of cross-validation. All three instruments could discriminate, classify, and predict grape must concentrate adulteration in Tokaj with a high accuracy and low error. The methods can be applied for routine quality checks of botrytized wines. PRACTICAL APPLICATION: Tokaj wines (Hungaricum) are botrytized wines acknowledged for the unique organoleptic properties bestowed by botrytized grape berries during production. Excluding these berries during wine production or manipulating the sugar content of low-grade wines to imitate high-grade wines are some recent suspicious activities that threaten the wine quality. Using advanced instruments, the electronic tongue, benchtop near infrared spectroscopy, and a handheld near infrared spectroscopy, we could discriminate, classify, and predict grape must concentrate adulteration in Tokaj with a high accuracy and low error. The models in our study can be applied for routine quality checks of botrytized wines.
托卡伊葡萄酒（Hungaricum）是一种经过贵腐菌感染的葡萄酒，以其独特的感官特性而闻名，这些特性是在生产过程中由贵腐葡萄浆果赋予的。在葡萄酒生产过程中排除这些浆果，或操纵低等级葡萄酒的含糖量以模仿高等级葡萄酒，是一些最近威胁葡萄酒质量的可疑活动。光谱和基于传感器的设备等先进方法因其快速、可靠和具有成本效益的分析而受到赞誉，但尚未有报道将其应用于监测贵腐葡萄酒中葡萄汁浓缩物的掺假情况。本研究旨在开发模型，使用电子舌（e-tongue）和两台近红外光谱仪（NIRS），快速区分经过人工掺假的低等级托卡伊葡萄酒“Forditas I”和“Forditas II”，这些葡萄酒的含糖量与高等级托卡伊葡萄酒相匹配。数据采用以下化学计量学方法进行评估：主成分分析（PCA）、判别分析（LDA）、偏最小二乘回归（PLSR）和 aquaphotomics（一种新方法）。所有三种仪器的 PCA 都显示出明显的分离模式，e-tongue 的 LDA 对掺假和未掺假葡萄酒进行了 100%的分类。来自 aquaphotomics 方法的 aquagrams 显示了重要的水吸收带，这些带可能成为托卡伊葡萄酒质量的标志物。PLSR 模型显示出 0.98（e-tongue）、0.97（台式 NIRS）、0.87（手持 NIRS）的决定系数（R CV）和低的交叉验证均方根误差。所有三种仪器都可以高精度和低误差地鉴别、分类和预测托卡伊葡萄酒中葡萄汁浓缩物的掺假。这些方法可用于贵腐葡萄酒的常规质量检查。
