Rapid and mobile determination of alcoholic strength in wine, beer and spirits using a flow-through infrared sensor.
Rapid and mobile determination of alcoholic strength in wine, beer and spirits using a flow-through infrared sensor.
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DOI：
10.1186/1752-153x-4-5
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发表时间：
2010-03-23
影响因子：
--
通讯作者：
Krieg G
中科院分区：
文献类型：
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作者：
Lachenmeier DW;Godelmann R;Steiner M;Ansay B;Weigel J;Krieg G
自从Gay-Lussac的时代以来，酒精浓度的体积（% vol）已经通过使用密度测量来确定。典型的参考程序包括蒸馏，然后进行比重瓶测定，这是一种劳动密集型的方法，因此价格昂贵。目前，红外（IR）光谱与多元回归相结合被广泛应用作为筛选程序，它允许在不到2分钟的时间内确定酒精浓度，而无需任何样品制备。缺点是傅立叶变换（FT）IR或近IR仪器的投资相对较大，并且需要矩阵相关校准。在这项研究中，我们应用了一种更简单的设备，该设备由一个专利的多光束红外传感器与一个用于自动酒精分析的流通池相结合组成，该设备具有便携式版本，可以进行现场测量。在方法验证过程中，发现红外传感器的精密度等于或优于密度法或FTIR法。例如，在6个不同的葡萄酒样品中测定的平均重复性为0.05%vol，相对标准偏差低于0.2%。通过分析260种不同的酒精饮料，与密度或FTIR结果进行比较，确保了准确性。相关性在从无酒精啤酒到高酒精度白酒的整个范围内呈线性，结果基本一致（R = 0.99981，p < 0.0001，RMSE = 0.279%vol）。该设备的适用性进一步证明了在发酵过程中对葡萄酒的分析，以及对未记录酒精（即非商业或非法产品）的测定。与典型的参考程序相比，流通式红外设备更容易操作，同时不需要耗时的样品制备步骤，如蒸馏。因此，酒精浓度可以经济快速地控制（每个样品需要少于60秒）。该设备还提供了移动的现场控制的机会，在葡萄酒，啤酒和烈酒的标签控制，发酵过程监测，或未记录的酒精的评估。
Ever since Gay-Lussac's time, the alcoholic strength by volume (% vol) has been determined by using densimetric measurements. The typical reference procedure involves distillation followed by pycnometry, which is comparably labour-intensive and therefore expensive. At present, infrared (IR) spectroscopy in combination with multivariate regression is widely applied as a screening procedure, which allows one to determine alcoholic strength in less than 2 min without any sample preparation. The disadvantage is the relatively large investment for Fourier transform (FT) IR or near-IR instruments, and the need for matrix-dependent calibration. In this study, we apply a much simpler device consisting of a patented multiple-beam infrared sensor in combination with a flow-through cell for automated alcohol analysis, which is available in a portable version that allows for on-site measurements. During method validation, the precision of the infrared sensor was found to be equal to or better than densimetric or FTIR methods. For example, the average repeatability, as determined in 6 different wine samples, was 0.05% vol and the relative standard deviation was below 0.2%. Accuracy was ensured by analyzing 260 different alcoholic beverages in comparison to densimetric or FTIR results. The correlation was linear over the entire range from alcohol-free beers up to high-proof spirits, and the results were in substantial agreement (R = 0.99981, p < 0.0001, RMSE = 0.279% vol). The applicability of the device was further proven for the analysis of wines during fermentation, and for the determination of unrecorded alcohol (i.e. non-commercial or illicit products). The flow-through infrared device is much easier to handle than typical reference procedures, while time-consuming sample preparation steps such as distillation are not necessary. Therefore, the alcoholic strength can be economically and quickly controlled (requiring less than 60 s per sample). The device also gives the opportunity for mobile on-site control in the context of labelling control of wine, beer and spirits, the process monitoring of fermentations, or the evaluation of unrecorded alcohols.