Roman Wine in Barbaricum. Preliminary Studies on Ancient Wine Recreation

Adaptation of Ancient Techniques to Recreate ‘Wines’ and ‘Beverages’ Using Withered Grapes of Muscat of Alexandria

The production of wines using ancient techniques is a present trend with commercial interest among consumers valorising their historical background. Therefore, the objective of the present work was to recreate wines and piquettes produced from dehydrated grapes, vinified according to the techniques described in classical Roman agricultural manuals. Muscat of Alexandria grapes were harvested and subjected to greenhouse drying under ambient temperature for 7 days, during the 2020 and 2021 harvests. When weight loss was approximately 30%, grapes were processed according to different protocols, including a rehydration step using saltwater or white wine (2020 harvest). Fermentation was conducted with the addition of commercial yeast without sulphur dioxide supplementation. The piquettes were obtained from the pressed pomaces diluted with water solution (5 g/L tartaric acid). The 2020 wines showed alcoholic content and residual sugar ranging from 14.8 to 17.0% (v/v), and 0.8 g/L to 18 g/L, respectively. Volatile acidity was less than 1 g/L (as acetic acid) in all wines, except for the fermentation of crushed grapes alone, which yielded 2.3 g/L volatile acidity. The fermentation of dehydrated crushed grapes in the semi-industrial trial run in the harvest of 2021 yielded 1.1 g/L volatile acidity. The piquettes analysis showed ethanol ranging from 10.2% (v/v) to 16.0% (v/v), reducing substances less than 2 g/L and volatile acidity less than 0.8 g/L. Overall, the physicochemical analysis showed that it was possible to recreate ancient winemaking techniques that may be further improved to produce commercially and legally acceptable wines.

Unique Brewing-Relevant Properties of a Strain of Saccharomyces jurei Isolated From Ash (Fraxinus excelsior)

The successful application of Saccharomyces eubayanus and Saccharomyces paradoxus in brewery fermentations has highlighted the potential of wild Saccharomyes yeasts for brewing, and prompted investigation into the application potential of other members of the genus. Here, we evaluate, for the first time, the brewing potential of Saccharomyces jurei. The newly isolated strain from an ash tree (Fraxinus excelsior) in Upper Bavaria, Germany, close to the river Isar, was used to ferment a 12°P wort at 15°C. Performance was compared directly with that of a reference lager strain (TUM 34/70) and the S. eubayanus type strain. Both wild yeast rapidly depleted simple sugars and thereafter exhibited a lag phase before maltose utilization. This phase lasted for 4 and 10 days for S. eubayanus and S. jurei, respectively. S. eubayanus utilized fully the available maltose but, consistent with previous reports, did not use maltotriose. S. jurei, in contrast, utilized approximately 50% of the maltotriose available, making this the first report of maltotriose utilization in a wild Saccharomyces species. Maltotriose use was directly related to alcohol yield with 5.5, 4.9, and 4.5% ABV produced by Saccharomyces pastorianus, S. jurei, and S. eubayanus. Beers also differed with respect to aroma volatiles, with a high level (0.4 mg/L) of the apple/aniseed aroma ethyl hexanoate in S. jurei beers, while S. eubayanus beers had a high level of phenylethanol (100 mg/L). A trained panel rated all beers as being of high quality, but noted clear differences. A phenolic spice/clove note was prominent in S. jurei beer. This was less pronounced in the S. eubayanus beers, despite analytical levels of 4-vinylguaiacol being similar. Tropical fruit notes were pronounced in S. jurei beers, possibly resulting from the high level of ethyl hexanoate. Herein, we present results from the first intentional application of S. jurei as a yeast for beer fermentation (at the time of submission) and compare its fermentation performance to other species of the genus. Results indicate considerable potential for S. jurei application in brewing, with clear advantages compared to other wild Saccharomyces species.