Activated carbon treatment to minimize VOC interferences in oxygen stable isotope analysis of beverages

Abstract

Oxygen stable isotope analysis is a well-established technique for determining the geographical origin and authenticity of beverages. However, volatile organic compounds (VOCs) present in some beverages can hinder accurate analysis. This study presents a straightforward method to overcome this challenge. Granular activated carbon co-incubated with the beverage sample during CO₂-H₂O equilibration effectively removes VOCs across a range of beverages tested. This includes propan-1-ol, 2-methylpropan-1-ol, ethyl acetate, 3-methylbutan-1-ol, 3-methylbutyl acetate, and ethyl hexanoate, achieving an average reduction of 77%. Consequently, this method minimizes background noise interferences, preserving δ¹⁸O values of water in a wide range of beverages, such as sake, sparkling sake, wine, beer, cider, awamori, brandy, shochu, whisky, and fruit juices. Notably, grain-derived alcoholic beverages like sake and beer exhibit more negative δ¹⁸O values compared to fruit-derived alcoholic beverages such as wine and cider, reflecting the distinct source waters and production processes employed. This universally applicable approach minimizes VOC interferences during oxygen stable isotope analysis of aroma-rich beverages. Its inherent simplicity and cost-effectiveness facilitate seamless integration into existing analytical workflows, leading to enhanced efficiency and productivity. This practical solution has potential for brand protection and authenticity verification within the beverage industry.