Terroir refers to the combination of environmental factors, such as climate, soil, and agricultural practices, that shape the characteristics of a crop, contributing to the unique qualities of the final product. The concept has been traditionally linked to wine, but some recent findings suggest that it also holds importance for distilled spirits. The expanding Irish distilling sector is shifting towards local raw materials such as wheat and rye, driven by regulatory changes, economic benefits, and consumer demand for sustainable local products. This research examines the effects of wheat variety, geographical location, and harvest year on grain composition and volatile composition of the new make spirit. For this study, twenty lab-scale wheat whiskey samples were produced from five different wheat varieties grown at two different locations in Ireland over two consecutive years. The wheat samples were analysed for grain composition and the volatile profiling of new make spirit samples by headspace solid-phase microextraction (HS-SPME) followed by gas chromatography–mass spectrometry (GC-MS). A total of fifty-one volatile compounds were detected, with ethanol, ethyl acetate, phenyl ethyl alcohol, and 3-methyl-1-butanol being predominant. Principal component analysis revealed that both the harvest year and geographical location moderately influenced the volatile compound distribution of the new make spirit, which is explained by a 43.25% variance. ANOVA analysis revealed that grain composition was significantly influenced by harvest year, location, and wheat variety. The 2020 samples showed higher protein and β-glucan content, whereas samples from the location Tipperary had higher starch content. This study indicates that terroir—specifically seasons (year) and geography (location)—affects the characteristics of wheat-based Irish whiskey, highlighting opportunities for distillers to differentiate their products by leveraging local environmental factors.

The term 'terroir' refers to the combination of all environmental elements that influence a crop's phenotype and impart character to distilled spirits through specific identifiable flavour compounds. While terroir's role in undistilled beverages such as wine and beer is well-established, its recognition in distilled spirits encounters scepticism because of the complexity of distillation and ageing processes that potentially obscure the raw material's original characteristics. However, this notion is now being extended to the realm of distilled spirits, with recent research validating the influence of terroir on the distinctive flavours of single-malt Irish whiskey. The Irish distilling sector is rapidly developing, innovating, and boosting the need for local raw materials, which includes exploring grains other than barley, such as wheat, rye, and maize. With a focus on the burgeoning demand for local ingredients and the diversification of grain in whiskey production, this paper reveals the potential for terroir as a marker of authenticity and quality in Irish whiskey. The review delves into the concept of terroir, its implications on Irish whiskey, both malted and grain-based, the diverse factors that shape the terroir, and the limitations of the concept of terroir in distilled spirits. By emphasising innovative practices and current trends, the research provides insights into the benefits of terroir for agricultural producers and distillers alike, while also proposing directions for future investigations to establish terroir more firmly in distilled beverages such as Irish whiskey.