Nanostructured Hybrid BioBots for Beer Brewing.

The brewing industry will amass a revenue above 500 billion euros in 2022, and the market is expected to grow annually. This industrial process is based on a slow sugar fermentation by yeast (commonly Saccharomyces cerevisiae). Herein, we encapsulate yeast cells into a biocompatible alginate (ALG) polymer along Fe3O4 nanoparticles to produce magneto/catalytic nanostructured ALG@yeast-Fe3O4 BioBots. Yeast encapsulated in these biocompatible BioBots keeps their biological activity (growth, reproduction, and catalytic fermentation) essential for brewing. Catalytic fermentation of sugars into CO2 gas caused a continuous oscillatory motion of the BioBots in the solution. This BioBot motion is employed to enhance the beer fermentation process compared to static-free yeast cells. When the process is finished, magnetic actuation of BioBots is employed for their retrieval from the beer samples, which avoids the need of additional filtration steps. All in all, we demonstrate how an industrial process such as beer production can be benefited by miniaturized autonomous magneto/catalytic BioBots.

Effect of Czech Hop Varieties on Aroma of Dry-Hopped Lager Beer.

The hoppy aroma in beer is characterized by an overall pleasant profile. The impacts of five Czech hop cultivars, Rubin, Saaz, Vital, Harmonie, and Kazbek, were tested on the hop aroma of the resulting beers, compared with a control beer sample, which was hopped with a commercial hop extract during wort boiling. GC-MS analysis was used for the identification and quantification of aroma-active compounds in the hops and beer. Dry hopping was successful in terms of improving the hoppy aroma in beer. Odorants such as ß-myrcene, linalool, geraniol, ß-citronellol, humulene epoxide I, and 2-methylbutyl-2-methylpropanoate were found at higher concentrations than the control in all dry-hopped beers. To quantify the success of dry hopping, the transfer rates of hop odorants were calculated. Those of linalool, geraniol and humulene epoxide I were adequate, whereas the transfer rates of polar compounds, e.g., ß-myrcene, were relatively low, mostly due to their polarity. Changes in hop oil constituents were clearly notable, with the generation of ß-citronellol, the release of other terpene alcohols from their glycosides or oxidation of α-humulene. Yeast metabolism also played an important role in these changes.