## 3 Results and Discussion  
### Yeast Analysis  
The selection of yeast strains (LA-01, LoNa, and W-34/70) was based on both their growing relevance to NAB production and their distinct fermentation characteristics [20,21]. LA-01 and LoNa are maltose-negative _Saccharomyces cerevisiae_ strains that are commercially available and have been developed and investigated specifically for the production of NABs through restricted fermentation [27,28]. Their limited ability to metabolize maltose and maltotriose minimizes ethanol formation during fermentation but also results in the development of fermentation-derived aroma compounds. These characteristics render them appropriate model organisms for investigating flavor development- and process-related parameters of NABs [20,21]. W-34/70, in contrast, is a bottom-ferenting lager strain (_Saccharomyces pastorisianus_) that has been widely used in the traditional brewing of full-strength beers [29]. However, when applied under constrained fermentation conditions, such as reduced fermentation temperatures, this strain can also be used to produce NABs. Its inclusion enables a comparison between specialized NAB strains and a conventional brewing yeast with modified fermentation parameters, thus providing a broader perspective on strain-dependent outcomes in NAB production. Dry yeasts offer numerous advantages, including ease of storage, precise dosing, and extended shelf life. Nevertheless, limitations remain despite recent advancements in freeze-drying methodologies. One common issue is cell wall disruption, which limits viable cell counts upon pitching, particularly when the yeast has been stored for extended periods or is close to its best-by date [39]. SEM images of the three yeasts in their freeze-dried state before pitching show a significant degree of cell wall disruption (Figure 1), particularly for LoNa. In contrast, W-34/70 exhibits some irregularly shaped cells but does not display a high proportion of damaged yeast cells. This could be attributed to the yeast drying process itself or may also be affected by the yeast nearing the end of its best-before date, as stated on the packaging [39]. Although W-34/70 is not typically used in microbiological processes to produce NAB, it remains one of the most commonly employed lager yeast strains and demonstrates considerable potential for low-alcohol beer production. Fermentation with this yeast is generally recommended within a temperature range of 12 to 18 \({}^{\circ}\)C [29]. However, because fermentation activity and the generation of flavor compounds such as higher alcohols and esters are often limited by word gravity during NAB production, a slight increase in the fermentation temperature to 20 \({}^{\circ}\)C was applied in this case. Yeast cell counts at pitching were not determined in this study. Instead, pitching rates were applied according to the respective manufacturers' recommendations [27,28,29], reflecting standard industry practice. In commercial brewing operations, craft brewers commonly follow these guidelines and often pitch dry yeast directly, without propagation or precise cell enumeration. As craft brewers typically do not quantify pitching cell counts but may implement beer filtration, the present study was intentionally designed to reflect practical brewing conditions. While the initial pitching rate does influence the yeast concentration at the end of fermentation, it does not necessarily correlate with the cell count at the filter inlet [11; 40; 41]. Several factors, including original gravity, nutrient availability, yeast growth kinetics, flocculation, sedimentation during fermentation, yeast cropping for reuse, and pre-filtration treatments such as centrifugation, can substantially affect the yeast load entering the filtration step [11; 23; 41; 42; 43]. To highlight the importance of monitoring yeast cells under these conditions, this analysis focused on determining the cell count at the filter inlet.