# Effect of Production Technique on Pilsner-Style Non-Alcoholic Beer (NAB) Chemistry and Flavor
## 3 Results and Discussion
### Evaluating the Impact of Production Technique on the Volatile Chemistry of the Different NABs
Compared to the other production techniques, membrane treatment resulted in significantly higher concentrations of furfural, methional, phenylacetaldehyde, pentanal, 3-methylbutanal, and 2-methylbutanal, whereas combined and vacuum treatments resulted in significantly lower concentrations of 2-methylbutanal and pentanal (one-way ANOVA based on technique, \(p<0.05\), data not shown). As mentioned in the introduction, numerous studies [14; 15; 18; 19; 34] have shown that adding hops at various stages throughout the brewing process can be an effective approach to positively alter the sensory profile of NAB. For the NABs evaluated, 75% of the products contained detectable concentrations of hop-related volatiles (Table S4). Linalool has previously been defined as a key hop volatile contributing to pilsner-style beer flavor [30] and has a reported flavor threshold of \(\sim\)5 \(\mu\)g/L [35]. Eight out of 20 (i.e., C9, MI2, C5, C4, RF2, RF5, RF1, and C6) of the samples tested contained linalool above its threshold. These eight NABs were also the beers that contained detectable levels of most of the other terpen and terpenally measured. Not surprisingly, the non-alcoholic IPA, MI2, contained the highest levels of most hop aroma compounds. However, C4, C5, and C9 were also rich in many terpen and terpenids and contained high levels of hop-derived 2-methylbutyl isobutyrate (64-307 \(\mu\)g/L). This suggests that novel hopping techniques, such as late and dry-hopping, were used in the production of these NABs. Further, even though this manuscript is concerned with pilsner type NAB and also does not specifically aim to discuss the impact of maltose intolerant yeast on hop flavor during NAB fermentation, it is very interesting to note that MI2 (i.e., the NA IPA produced with MI yeasts) contained high levels of citronellol (39 \(\mu\)g/L). Some yeast strains have been shown to convert geraniol into citronellol during fermentation, which can increase the citrus flavor of beer [35]. Therefore, the ability of MI yeasts in modifying hop-derived volatiles during fermentation could be interesting to investigate in the future. Previously, hop aroma and fruity character of NABs were shown to drive consumer liking, while DMS was shown to increase the perception of \"beer likeness\" in NAB [15; 16]. Overall, when considering DMS concentrations in pilsner-style NAB made from 100% malt bills (Table S4), the samples might simply be divided into those that contained DMS (29 to 54 \(\upmu\)g/L) and those that did not contain detectable levels of DMS. Beers that did not contain DMS at a concentration greater than 10 \(\upmu\)g/L were the vacuum dealcoholized NAB V1-V4, as well as C1 and C7 which were produced using combined treatments. Given the low boiling point of DMS and the absence of DMS in vacuum dealcoholized beers, one can assume that C1 and C7 are made with a major share of vacuum dealcoholized beer. If desired, it is possible that blending a NAB made from restricted fermentation might be a suitable approach for increasing \"beer likeness\" in NABs made via vacuum distillation. Previously, NABs with higher skunk aroma quality (also known as \"lightstruck\") were not highly preferred by consumers [15] but were perceived to be more beer-like [16]. Although they did not have analytical data, the authors of these studies hypothesized that the increase in the skunk quality in the NABs evaluated was due to the increase of 3-methylbut-2-ene-1-thiol (3-MBT)--3-MBT can result from either the direct or indirect irradiation of iso-\(\alpha\)-acids as shown to be the case in alcoholic pilsners [36]. Therefore, in this study, the 3-MBT concentration was evaluated in the NABs. The 3-MBT concentration was the highest in V3 at 23.8 ng/L and the four NABs packaged in green bottles had an average of 13.3 (ng/L), whereas the average 3-MBT content for the rest of the NABs was 4.5 ng/L.