The Influence of Malt Variety and Origin on Wort Flavor

Beer flavor is primarily impacted by malt kilning and the choice of yeast/hops in the beer recipe. Although barley malt is the material backbone of most beers, variety has until recently been largely overlooked with respect to flavor differences. In this study, 11 malt variety samples from multiple Australian and international (UK, Canada, China) growing regions were infusion mashed (65 degrees C) at laboratory scale to produce unboiled wort to investigate differences between the flavor profiles observed with sensory assessment and headspace-SPME gas chromatography-mass spectrometry (HS-SPME GC-MS). Sensory evaluation identified wort flavor differences with the control heritage samples, Maris Otter/Schooner, having the highest overall flavor complexity and acceptability. The Chinese malted Chinese/Canadian samples had the lowest overall flavor complexity rankings. Overall, flavor complexity was correlated with KI, malt protein (negative), and beta-glucosidase (negative), while sweetness intensity was correlated with limit dextrinase and pH. HS-SPME GC-MS analysis focused only on compounds that were significantly different between varieties (ANOVA, P <= 0.05). Overall, 107 compounds were identified with significantly different levels between the varietal worts. The resultant PCA plots (overall, aldehydes, alcohols, esters, organic acids, terpenes, ketones) supported the sensory assessment, with Maris Otter and the Australian samples clustering in different PCA sectors compared to the Chinese malted Canadian/Chinese samples. These findings provide a basis for key compound identifications that influence malt flavor through the brewing process. The results have the potential to assist barley breeders in selecting optimized germplasm for future variety development and can assist maltsters and brewers to consistently target desired flavors for finished beers and potentially whisk(e)y.