Service Commun des Laboratoires, 3 Avenue du Dr A. Schweitzer, 33608 Pessac, France.
Food Chem. 2013 Dec 1;141(3):2103-7. doi: 10.1016/j.foodchem.2013.04.112. Epub 2013 May 16.
A procedure to detect whether carbon dioxide was added to French ciders has been developed. For this purpose, an optimised and simplified method is proposed to determine (13)C/(12)C isotope ratio of carbon dioxide (δ(13)C) in ciders. Three critical steps were checked: (1) influence of atmospheric CO2 remaining in the loaded vial, (2) impact of helium flush, (3) sampling speed. This study showed that atmospheric CO2 does not impact the measurement, that helium flush can lead to isotopic fractionation and finally, that a fractionation occurs only 5h after bottle opening. The method, without any other preparation, consists in sampling 0.2 mL of cold (4 °C) cider in a vial that is passed in an ultrasonic bath for 10 min at room temperature to enhance cider de-carbonation. The headspace CO2 is then analysed using the link Multiflow®-isotope ratio mass spectrometer. Each year, a data bank is developed by fermenting authentic apples juices in order to control cider authenticity. Over a four year span (2008-2011), the CO2 produced during the fermentation step was studied. This set of 61 authentic ciders, from various French production areas, was used to determine a δ(13)C value range of -22.59±0.92‰ for authentic ciders CO2 bubbles. 75 commercial ciders were analysed with this method. Most of the samples analysed present a gas δ(13)C value in the expected range. Nevertheless, some ciders have δ(13)C values outside the 3σ limit, revealing carbonation by technical CO2. This practice is not allowed for organic, "Controlled Appellation of Origin" ciders and ciders specifying natural carbonation on the label.
已经开发出一种检测法国苹果酒中是否添加二氧化碳的方法。为此，提出了一种优化和简化的方法来确定苹果酒中二氧化碳的（13）C/（12）C 同位素比值（δ（13）C）。检查了三个关键步骤：（1）装入小瓶中残留的大气 CO2 的影响，（2）氦气冲洗的影响，（3）采样速度。该研究表明，大气 CO2 不会影响测量结果，氦气冲洗会导致同位素分馏，最后，仅在打开瓶子 5 小时后才会发生分馏。该方法无需任何其他准备，包括在小瓶中采集 0.2 毫升冷（4°C）苹果酒，然后将小瓶在室温下通过超声浴 10 分钟，以增强苹果酒脱碳。然后使用 Multiflow®-同位素比质谱仪分析顶空 CO2。每年，通过发酵正宗的苹果汁来开发一个数据库，以控制苹果酒的真实性。在四年期间（2008-2011 年），研究了发酵过程中产生的 CO2。这一组 61 种来自法国不同生产地区的正宗苹果酒用于确定正宗苹果酒气泡的 δ（13）C 值范围为-22.59±0.92‰。用这种方法分析了 75 种商业苹果酒。分析的大多数样品的气体 δ（13）C 值在预期范围内。然而，一些苹果酒的 δ（13）C 值超出了 3σ 限制，表明碳化是通过技术 CO2 实现的。这种做法不允许用于有机的、“受控制的原产地名称”苹果酒和在标签上注明天然碳化的苹果酒。
