What Does near Infrared Have to Offer in Confirming Wine Authenticity and Origin?

Abstract

Introduction T he determination of food authenticity and adulteration are major issues in the food and wine industries. In particular, the verification of authenticity, origin and traceability of wine and other alcoholic beverages by means of near infrared (NIR) spectroscopy has become a field of increased interest in recent years. More and more, consumers are demanding wines produced by traditional methods as well as targeting regional and handmade (e.g. craft) methods of production over commercial practices for many reasons. Almost 60% of the wine produced worldwide is consumed in Europe. Although the EU is the world’s leading wine importer, it also has three of the larger wine producing countries in the world (France, Italy and Spain). However, the number of countries outside Europe producing and exporting wine is increasing, as is the relevance of this sector within the food industry as a whole. The Australian wine industry is one of the largest exporters (fifth in terms of volume) in the world, with the South Australian wine industry producing annually more than 50% of the Australian wine output. Geographical regions of South Australia such as the Coonawarra, Barossa Valley, Clare Valley and McLaren Vale are well known internationally for their wines (e.g. Shiraz). Although these regions might be considered as geographically similar, differences in soil and climate characteristics between them confer well-defined, characteristic quality properties to the wine produced. The modern wine industry continues to have a requirement for rapid, inexpensive and effective techniques to measure chemical properties in wine as well as to assure consumers of the geographic provenance of the bottled wine. Nowadays, wine marketing strategies focus on associating the product image and the perception of quality with a specific region and/or grape variety or varietal blend. More than any other product of the land, the flavours and aromas of wine are linked to the soil and soil differences are often emphasised by wine makers as part of their marketing strategies which focus the importance of terroir. Although the quality of a wine depends primarily on the type of grape involved in its production, the interactions between climate and soil together with the different techniques used during production (e.g. fermentation, maturation) also play an important role in defining the overall quality of the wine. Wines produced in specified regions are clearly identified and controlled by different governing bodies at both the national and regional level. For example, in the EU, a wine produced in a specific region with well-defined cultivation and elaboration practices, verifiable by the competent bodies, is awarded the Denomination of Origin (DO). This denomination guarantees the provenance indicated on the label as well as indicating a superior quality to the consumer. Additionally, geographical denominations bring many advantages to producers and consumers, such as protecting these products from possible frauds, guaranteeing high product quality standards and defining strict production protocols, regulations and policies for production. Geographical denominations are also useful to preserve the local agricultural environment because the quality and composition of a given product is strictly linked with the production environment and traditions. Worldwide, several laboratories evaluate different techniques in order to assure producers and consumers about the denomination of origin or the authenticity of a wine using labour-intensive and costly analyses which look for specific chemical features that can be related to a particular geographical origin. Several parameters can be used in order to determine the geographic origin of wine and these are defined as indicators of wine origin. Examples of wine geographical origin indicators are the mineral content, micro and trace elements, isotopes, amino acids, phenolic and volatile compounds. However, this type of analysis is based on instrumental techniques that, being selective and reliable, require experienced operators and are difficult to automate and implement in routine and on-site applications. Nowadays, wine producers and exporters, regulators and consumers are all demanding better analytical tools for cost-effective and routine quality control.