## 1 Introduction  
The issue of food authentication has become particularly relevant in recent years due to the intensification of illegal practices such as fraud and counterfeiting. Alcoholic beverages are particularly subject to these practices because of their high demand and their significant impact on the economic sector of many countries [1]. In the EU alone, there are 47 categories of spirit drinks and approximately 250 geographical indications (GIs) from different countries [2]. The quality, sensory features and reputation of GIs are strictly linked to the country, locality or region of their geographical origin [3]. A recent study found that the sales value of a product with a protected name is, on average, double that of similar products without a certification [4]. Alcoholic beverages with GIs include, among others, \"Grappa\" (Gr) and \"Brandy Italiano\" from Italy and GI Brandies from other European countries, such as \"Brandy de Jerez\" from Spain, \"Deutscher Weinbrand\" from Germany and \"Brandy Francais\" from France. These beverages must comply with the category standards set by the EU Commission regarding presentation, labeling, origin and production process [5] as well as with the peculiar GI product specifications. \"Grappa\", for instance, can only be produced from grapes grown, vinvified, distilled and fined in Italy [6], while \"Brandy de Jerez\" is obtained and aged in the Spanish province of Cadiz only in the three localities of Sanlucar de Barrameda, Jerez de la Frontera and El Puerto de Santa Maria [7] following specific production steps described in the product specification itself. It is evident that the ability to verify the origins and technological paths of these products is crucial for counteracting fraud. Different approaches have been developed to verify compliance with the above-mentioned regulations and authenticate Gr and wine brandy (WB) GIs. Many of these approaches use traditional analytical techniques such as chromatography, mainly coupled to mass spectrometry, with the aim of identifying marker compounds for discrimination [8]. These methodologies are very effective but often time- and/or sample-consuming and expensive. Other approaches use different techniques mostly based on spectroscopic methods and, to a lesser extent, other methods such as those based on multisensory systems (electronic nose and tongue) coupled with chemometrics to obtain an overall profile of the many compounds constitutive of the product without identifying specific congeners. These untargeted methods are usually rapid, non-destructive and cost-effective. Both approaches can furnish accurate results in terms of discriminating power and have both advantages and disadvantages. The aim of this review is to provide an overview of studies on the techniques for the authentication and quality control of distillates with a specific target on Gr and WB GIs, covering the research carried out in the last decade. The subject has been divided into five main chapters concerning spectroscopic, chromatographic and hyphenated methods; sensor arrays; multi-platform techniques; and other methods. For each chapter, the pertinent chemometric methods are briefly described, directing the reader to basic references for more in-depth explanations. In the final chapters, an overview of chemometric tools applied in the authentication of Gr and WB GIs and technical challenges and future perspectives are highlighted.