Elemental composition, rare earths and minority elements in organic and conventional wines from volcanic areas: The Canary Islands (Spain)

Pablo Alonso Gonzalez,Octavio Pérez Luzardo,Paula Arribas Blázquez,Manuel Luis Zumbado Peña,Carmelo Andújar,Eva Parga-Dans,Ángel Rodríguez-Hernández,María Mercedes Hernández González,Antonio Peña-Fernández

doi:10.1371/journal.pone.0258739

Abstract

The organic wine market is rapidly growing worldwide, both in terms of production and consumption. However, the scientific literature is not conclusive regarding differences in the elemental composition of wines according to their production method, including both major and trace elements. Minerals can be present in wine as a result of both anthropogenic and environmental factors. To date, this has not been evaluated in volcanic contexts, neither has the emergent issue of rare earths and other minority elements as potential sources of food contamination. This study using inductively coupled plasma mass spectrometry (ICP-MS) analyses organic and conventional wines produced in the Canary Islands (Spain), an archipelago of volcanic origin, to compare their content of 49 elements, including rare earths and minority elements. Our results showed that organic wines presented lower potential toxic element content on average than their conventional counterparts, but differences were not significant. Geographical origin of the wine samples (island) was the only significant variable differentiating wine samples by their composition profiles. By comparing our data with the literature, no agreement was found in terms of differences between organic and conventionally-produced wines. This confirms that other factors prevail over elemental composition when considering differences between wine production methods. Regarding the toxicological profile of the wines, five samples (three organic and two conventional) exceeded the maximum limits established by international legislation. This highlights the need for stricter analytical monitoring in the Canary Islands, with a particular focus on Cu and Ni concentration, and potentially in other volcanic areas.

Highlights

Wine, defined as the product resulting from the fermentation of grape must, is one of the oldest and most globally consumed alcoholic beverages
Few papers report comparisons between the elemental composition of conventional and organic wines. This is the first study to do so for the Canary Islands, it reveals that the island factor is the only statistically significant variable to differentiate wine samples
The results of this study confirm previous research showing no agreement between production method and wine’s elemental profile

Summary

Introduction

Wine, defined as the product resulting from the fermentation of grape must, is one of the oldest and most globally consumed alcoholic beverages. Wine can contain elements that can contribute to human nutrition or be toxic and deleterious, often depending on their concentration. For instance Cu and Zn, are essential human minerals but can become toxic in high amounts, while other elements like As, Hg, Cd and Pb are ecotoxic and potentially detrimental for humans even at very low doses [1]. It is widely accepted that accumulation of heavy metals in the food chain has deleterious consequences for human health [4]. The presence of particular metals in wine, even in low quantities, may significantly affect its quality and organoleptic characteristics such as aroma, taste and colour, potentially leading to a range of oenological problems [5]

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