Carbon isotope ratio (Δ13C) and phenolic profile used to discriminate wines from Dealu mare and Cotnari regions (Romania)

Abstract

Regarding the food quality, authenticity is one of the most important issues in the context of ensuring the safety and security of consumers, but is also more important when it comes to wine (one of the most counterfeited foods in the world).

A batch of 28 wines of Romanian varieties obtained in two regions well known for the production of wines from Romania (Dealu Mare and Cotnari) was analyzed from a physical-chemical point of view in order to discriminate them according to geographical origin and variety. The assessment of the carbon isotope ratio in ethanol extracted from wine provides relevant information to validate the geographical origin of wines. At the same time, the phenolic compounds in wine composition are of great importance, they contribute to the formation of characteristics such as taste, color and structure. The profile of these compounds is very different depending on grape variety, climatic conditions in each area and the applied wine-making technology. Therefore, a correlation between the carbon isotope ratio and the phenolic compounds profile can provide an overview of wines of a certain variety or region. Thus, the carbon isotope ratio (δ13C) was determined for all wines in this batch, which varied between -27.13 and -25.83 for wines from the Dealu Mare region and between -28.27 and -25.66 for wines from the Cotnari region. Also 12 phenolic compounds (gallic acid, protocathecic acid, caftaric acid, caffeic acid, coumaric acid, trans resveratrol, hydroxytyrosol, tyrosol, procyanidin dimer B1 and procyanidin dimer B2, catechin and epicatechin) were identified and quantified.
The δ13C measurements have been performed using an elemental analyser VarioMicroCube, Elementar coupled to an isotope ratio monitoring by mass spectrometry (Isoprime, Elementar) while the phenolic compounds content was analyzed by high-performance liquid chromatography (HPLC-PDA). In order to differentiate the wine samples according to the geographical region and the variety, statistical analysis was applied and thus a good discrimination of the wines according to the region and at the same time of the varieties within the same region was achieved.