Influence of Malting Procedure on Volatile Composition of Rye Brome (Bromus secalinus L.): A Pilot Study

This study investigated the volatile profile dynamics of wild rye brome (Bromus secalinus L.) subjected to a pilot-scale malting run to evaluate its technological potential as a novel grain substitute. Headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS) was utilized to analyze ground samples of raw seeds (BR-Seed) and malted grain (BR-Malt) in technical triplicates (n = 3). A total of 30 volatile compounds were identified across samples (29 in BR-Seed, 24 in BR-Malt). Malting resulted in an overall attenuation of total volatile concentration. Aldehydes constituted the predominant chemical class in both raw seeds and malt, representing 60.13% and 63.00% of total volatilome mass, respectively. Ketones exhibited the most substantial decline during malting, decreasing from 12.50% of total volatiles in seeds to 3.69% in malt, with key off-flavor compounds such as 2-heptanone and 1-octen-3-ol dropping below detection or diminishing substantially. In both seeds and malt, 2-hexenal was present at the highest relative abundance, though its levels decreased 4.35-fold post-kilning (234.53 µg 2-undecanone equivalents to 53.93 µg 2-undecanone equivalents). Crucially, key staling aldehydes (trans-2-nonenal and hexanal) were absent in the malted grain. These pilot-scale baseline findings demonstrate that malting could be an useful method of decreasing various volatiles from rye brome, possibly resulting in a different sensory profile that could support its further development in brewing and baking applications.