Jessika De Clippeleer

Consumers are more than ever in search of novel and exciting beer choices, and brewers are, therefore, continuously experimenting to adapt their product portfolio. One interesting way to naturally incorporate novel flavors and tastes is by using alternative adjuncts, but this is not always an easy and straightforward process. In this study, a 40% unmalted alternative adjunct (einkorn, emmer, spelt, khorasan, quinoa, amaranth, buckwheat, sorghum, teff, and tritordeum) or reference (barley malt, unmalted barley, and unmalted wheat) was added to 60% barley malt, after which three different laboratory mashing processes (Congress mash, Congress mash with pre-gelatinization of the adjunct, and Evans mash) were performed, and their behavior during mashing and the resulting wort characteristics were investigated in detail. Overall, the extraction process of all 10 unmalted alternative adjuncts was not complete for all three laboratory mashing processes, whereby Congress mashing resulted in the highest extract and fastest filtration, whereas Evans mashing resulted in the lowest extract and slowest filtration. Pre-gelatinization of the unmalted was generally only beneficial for adjuncts with high onset starch gelatinization temperatures. This process also inactivated endogenous enzymes in the unmalted adjuncts, which had an adverse effect on the mashing process.

This study provides a comprehensive comparison among the most common gluten-free (GF) brewing practices, with a focus on the impact of each treatment on physicochemical parameters and consumer acceptability of the final beer. In addition, the influence of a longer cold maturation on the natural reduction of the gluten content was investigated. Prolyl endopeptidase addition was found to be the most effective treatment in reducing gluten levels (−75.93%), followed by silica gel (−53.09%), longer cold maturation (−4.32%), and tannins (−1.85%). Nonetheless, none of the treated beer samples was gluten-free (gluten content > 20 ppm) due to the high nitrogen content of the original wort. The silica gel application treatment affected the physicochemical and sensory characteristics of the final beer the least. According to the difference from control test results, no significant difference in terms of overall liking, appearance, odor/aroma, or taste was observed between the silica gel-treated sample and control beer (p > 0.05). On the other hand, the application of enzymes and tannins significantly affected the appearance and the beer odor/aroma. Nevertheless, all beer samples received positive sensory acceptance scores.

Acetic acid bacteria (family Acetobacteraceae ) are found in the gut of most insects. Two clades are currently recognized: Commensalibacter–Entomobacter and Bombell a– Oecophyllibacter . The latter group is only found in hymenopteran insects and the described species have been isolated from bees and ants. In this study, two new strains DDB2-T1^T (=KACC 21507^T=LMG 31759^T) and DM15PD (=CCM 9165=DSM 112731=KACC 22353=LMG 32454) were isolated from wasps collected in the Republic of Korea and Germany, respectively. Molecular and phenotypic analysis revealed that the strains are closely related, with 16S rRNA gene sequences showing 100 % identity and genomic average nucleotide identity (ANI) values ≥99 %. The closest related species based on type strain 16S rRNA gene sequences are Swingsia samuiensis , Acetobacter peroxydans , Bombella favorum and Bombella intestini (94.8–94.7% identity), whereas the closest related species based on type strain genome analysis are Saccharibacter floricola and Bombella intestini (ANI values of 68.8 and 68.2 %, respectively). The reconstruction of a phylogenomic tree based on 107 core proteins revealed that the branch leading to DDB2-T1^T and DM15PD is localized between Oecophyllibacter and Saccharibacter–Bombella. Further genomic distance metrics such as ANI, percentage of conserved proteins and alignment fraction values were consistent with these strains belonging to a new genus. The key phenotypic characteristics were one MALDI-TOF-MS peak (m/z=4601.9±2.0) and the ability to produce acid from d-arabinose. Based on this polyphasic approach, including phylogenetics, phylogenomics, genome distance calculations, ecology and phenotypic characteristics, we propose to name the novel strains Aristophania vespae gen. nov., sp. nov., with the type strain DDB2-T1^T (=KACC 21507^T=LMG 31759^T).

Wort was prepared according to the Congress mash protocol with the addition of 40% unmalted barley, tritordeum, or quinoa. Mashes with quinoa filtered significantly slower than mashes with barley. In contrast, tritordeum filtered similarly as barley, even though tritordeum does not possess a husk. The lack of husk may have contributed to a higher extract yield of tritordeum compared to barley. The final 65 °C mash protocol resulted in shorter saccharification times, but slower wort filtration compared to the Congress mash protocol. When unmalted adjuncts were pregelatinized by heating in water for 20 min at 95 °C, the filtration following the Congress mash protocol was slower and the filtration following the final 65 °C mash protocol was faster than the same mashes prepared without pregelatinization. Pregelatinization also inactivated the endogenous enzymes in the (pseudo)cereals used. This was especially noticeable for quinoa, resulting in wort with markedly lower glucose concentrations, most likely due to the inactivation of endogenous amyloglucosidases. Wort filtration improved for both mashing protocols when an exogenous enzyme mix (Brewers Compass®) was added to each of the three different (pseudo)cereals. Furthermore, addition of the enzyme mix increased the extract yield of the final 65 °C mashes and the FAN levels of the Congress mashes. These findings confirmed the benefit of using the Brewers Compass® enzyme mix during mashing processes with high percentages of (up to 40%) unmalted (pseudo)cereals.

Lentils, a popular foodstuff worldwide, are gaining more interest for their use in alternative diets. In addition, we are observing an ever-growing demand for new raw materials in the malting and brewing industry and an overall rising interest in a low-gluten lifestyle. Therefore, in this study, malt was produced from green lentils and used in both laboratory- and pilot-scale brewing trials. Malted lentils were used as 10% and 20% adjuncts at the laboratory scale, following the Congress mash procedure, and the most important parameters (e.g., filtration time, pH, color, extract, fermentability) of the wort and beer samples were analyzed with a special focus on the concentrations of metal ions (Mg²⁺, Ca²⁺, Zn²⁺, Fe) in wort. The production of beer with lentil malt as an adjunct was then scaled up to 1 hl, and several beer parameters were analyzed, including the gluten content and foam stability. The results showed that the gluten content was decreased by circa 35% and foam stability was enhanced by approximately 6% when adding 20% lentil malt. Furthermore, the use of lentil malt reduced the filtration time by up to 17%. A trained panel evaluated the sensorial qualities of the produced beers. Overall, the use of green lentil malt shows promising results for its potential use in brewing.