Recipe, volatiles profile, sensory analysis, physico-chemical and microbial characterization of acidic beers from both sourdough yeasts and lactic acid bacteria

Lachancea thermotolerans, an Innovative Alternative for Sour Beer Production

The interest in and growth of craft beer has led to an intense search for new beers and styles. The revival of traditional styles has sometimes been hampered by the use of microorganisms such as lactic acid bacteria. Therefore, studies on alternative yeasts for the production of this style of beer have increased. In this work and together with previous studies carried out with yeasts isolated from Madrid agriculture (from grapes, must, wine, vineyards and wineries), the capacity of 10 yeast strains, belonging to the genus Lachancea thermotolerans, for the production of sour beer has been determined. For this purpose, different fermentation scale-ups (100 mL, 1 L and 100 L) have been performed and their fermentation capacity, aroma compound production (33 volatile compounds by GC), organoleptic profile (trained tasting panel and consumers), melatonin production (HPLC) and antioxidant capacity have been studied. Beer fermented with yeast strain CLI 1232 showed a balanced acidity with a fruity aromatic profile and honey notes. On the other hand, the beer fermented with strain 1-8B also showed a balanced acidity, but less fruity and citric flavour than CLI 1232 strain. Finally, the yeast strain selected by the consumers (CLI 1232) was used for beer production at industrial scale and the market launch of a sour beer.

Scent of knowledge: The molecular fingerprint of volatiles in an emblematic historical library in Italy

Heritage guidelines recognize odors as a value associated with a place. This study aims to clarify the connection between heritage and volatile organic compounds at the molecular level. At variance with previous studies, usually focused only on book-related compounds from accelerated degradation tests, the whole air of one of the most significant historical libraries in Italy was studied. A sampling of the volatiles off-gassing from the two most iconic rooms, respectively open and forbidden to visitors, was performed via a non-invasive, nondestructive green method, solid-phase-micro-extraction. The gas-chromatographic analyses resulted in the appraisal of olfactory contributions from books, storage environment, and, for the first time, anthropic activities and pollution.Concerning the paper decay process, for the very first time, the presence of 2-ethyl-1-hexanol in the chromatographic signature of the library air is rationalized according to the Guerbet reaction. The presence of all other compounds is explained by the paper decay process, anthropic sources, and pollution. Indoor air comprises analytes related to paper decay, identified by previous studies, and additional compounds never found before.Most volatile compounds are aliphatic and aromatic hydrocarbons, aldehydes, alcohols, terpenes, and terpenoids. Odor contributions from a selected number of analytes were pinpointed. Alkanes dominate the volatiles chromatographic signature, and impart a slight hydrocarbon smell. Aromatics supplement their characteristic aromatic odor. Aldehydes' very low odor threshold makes them strongly contribute to both fruity and fatty descriptors. Benzaldehyde, furfural, vanillin, and camphor add, respectively, an hint of almond, bread, vanilla, and camphor. Alcohols such as 2-ethyl hexanol have a floral scent. Wood-related terpenes and terpenoids contribute to the woody smell of the library.The digital molecular fingerprint of the "scent of knowledge" enables documentation, conservation, and future chemical reproduction of the historical library odor.

Chemical Recycling of Plastic Marine Litter: First Analytical Characterization of The Pyrolysis Oil and of Its Fractions and Comparison with a Commercial Marine Gasoil

A detailed molecular fingerprint of raw pyrolysis oil from plastic wastes is a new research area. The present study focuses for the first time on the chemical recycling of plastic marine litter; we aim to chemically characterize the obtained raw pyrolysis oil and its distillates (virgin naphtha and marine gasoil) via GC-MS and FT-IR. For all samples, more than 30% of the detected compounds were identified. 2,4-dimethyl-1-heptene, a marker of PP pyrolysis, is the most represented peak in the chemical signature of all the marine litter pyrolysis samples, and it differentiates commercial and pyrolysis marine gasoil. The presence of naphthalenes is stronger in commercial gasoil, compared to its pyrolysis analog, while the opposite holds for olefins. The overlap between the two molecular fingerprints is impressive, even if saturated hydrocarbons are more common in commercial gasoil, and unsaturated compounds are more common in the gasoil derived from pyrolysis. A technical comparison between the commercial marine gasoil and the one obtained from the marine litter pyrolysis is also attempted. Gasoil derived from marine litter fully complies with the ISO8217 standards for distillate marine fuel. On the other hand, the virgin naphtha is particularly rich in BTX, ethylbenzene, styrene, and alpha olefins, which are all important recoverable platform chemicals for industrial upcycling.

Analysis of volatiles organic compounds in Venice lagoon water reveals COVID 19 lockdown impact on microplastics and mass tourism related pollutants

The Lagoon of Venice is a continuously evolving ecosystem that rapidly responds to anthropic stressors. The UNESCO World Heritage site "Venice and its Lagoon", is one of the top tourist destinations in the world. Mass tourism increases marine litter, water traffic emissions, solid waste, and sewage release. Plastic marine litter is not only a major aesthetic problem diminishing tourists experience of Venice, it also leaches contaminants into the seawater. Since there is a dearth in the literature regarding microplastic leachable compounds and overtourism related pollutants, the project studied the Head Space-Solid Phase Micro Extraction-Gas Chromatography-Mass Spectrometry (HS-SPME-GC-MS) molecular fingerprint of volatile lagoon water pollutants, to gain insight into the extent of this phenomenon in August 2019. The chromatographic analyses enabled the identification of 40 analytes related to the presence of polymers in seawater, water traffic, and tourists habits. In Italy, on the 10th March 2020, the lockdown restrictions were enforced to control the spread of the SARS-CoV-2 infection; the ordinary urban water traffic around Venice came to a halt, and the ever-growing presence of tourists suddenly ceased. This situation provided a unique opportunity to analyze the environmental effects of restrictions on VOCs load in the Lagoon. 17 contaminants became not detectable after the lockdown period. The statistical analysis indicated that the amounts of many other contaminants significantly dropped. The presence of 9 analytes was not statistically influenced by the lockdown restrictions, probably because of their stronger persistence or continuous input in the environment from diverse sources. Results signify a sharp and encouraging pollution decrease at the molecular level, concomitant with the anthropogenic stress release, even if it is not possible to attribute quantitatively the VOCs load variations to specific sources (e.g., tourists' habits, urban water traffic, plastic pollution).

Autochthonous Biological Resources for the Production of Regional Craft Beers: Exploring Possible Contributions of Cereals, Hops, Microbes, and Other Ingredients

Selected biological resources used as raw materials in beer production are important drivers of innovation and segmentation in the dynamic market of craft beers. Among these resources, local/regional ingredients have several benefits, such as strengthening the connection with territories, enhancing the added value of the final products, and reducing supply costs and environmental impacts. It is assumed that specific ingredients provide differences in flavours, aromas, and, more generally, sensory attributes of the final products. In particular, of interest are ingredients with features attributable and/or linked to a specific geographical origin. This review encompasses the potential contribution and exploitation of biodiversity in the main classes of beer inputs, such as cereals, hops, microbes, and adjuncts, with a specific emphasis on autochthonous biological resources, detailing the innovative paths already explored and documented in the scientific literature. This dissertation proposes an overview of the impact on beer quality for each raw material category, highlighting the benefits and limitations that influence its concrete applications and scale-up, from the field to the stain. The topics explored promote, in the sector of craft beers, trends already capitalised in the production of other alcoholic beverages, such as the preservation and revalorisation of minor and autochthonous varieties, the exploitation of yeast and bacteria strains isolated from specific sites/plant varieties, and the valorisation of the effects of peculiar terroirs on the quality of agricultural products. Finally, the examined tendencies contribute toward reducing the environmental impacts of craft beer manufacturing, and are in line with sustainable development of food systems, increasing the economic driver of biodiversity preservation.

Sourdough improves the quality of whole-wheat flour products: Mechanisms and challenges-A review

Increasing the intake of whole-wheat flour (WWF) products is one of the methods to promote health. Sourdough fermentation is increasingly being used in improving the quality of WWF products. This review aims to analyze the effect of sourdough fermentation on WWF products. The effects of sourdough on bran particles, starch, and gluten, as well as the rheology, antinutritional factors, and flavor components in WWF dough/products are comprehensively reviewed. Meanwhile, sourdough fermentation technology has a promising future in reducing anti-nutritional factors and toxic and harmful substances in WFF products. Finally, researchers are encouraged to focus on the efficient strain screening and metabolic pathway control of sourdough for WWF products, as well as the use of bran pre-fermentation and integrated biotechnology to improve the quality of whole-wheat products. This review provides a comprehensive understanding of the effect of sourdough fermentation technology on wholemeal products to promote WWF production.

Impact of germination on the chemical profile of HomChaiya rice wort and beer

HomChaiya rice is one of the important rice varieties in Thailand. However, the commercial value of this rice is very limited as it is not widely known and has limited availability. The present research aimed to produce an alcoholic beverage from malted HomChaiya rice, and various chemical profiles (physicochemical, phytochemicals, volatiles, and amino acids) were studied. HomChaiya rice was germinated for different periods (3, 5, and 7 days), kilned at 60 °C, and used to produce wort and beer. Physicochemical qualities such as pH, brix, titratable acidity, viscosity, soluble nitrogen, FAN, and extractability were higher in the wort, and the results were significantly influenced by the germination time. On the other hand, the color values were higher in the beer samples, and prolonged germination brightened the beer color. The total phenolic content, flavonoid content, and various antioxidant potentials (DPPH, ABTS, and reducing power) were significantly increased in the beer samples when made with rice malt germinated for 7 days compared to the wort under similar conditions. Wort samples had 13 identified volatiles, whereas the beer samples had 30 volatile compounds. Furthermore, 20 amino acids were identified, and most of them were found at a higher level in the wort samples compared to beer samples, and prolonged germination slightly increased the amino acid levels. The beer samples' sensory characteristics showed that the HomChaiya rice germination period had no significant effect.

An alcoholic beverage from malted HomChaiya rice was produced and various chemical profiles and sensory characteristics were studied.

Chemical Composition of Sour Beer Resulting from Supplementation the Fermentation Medium with Magnesium and Zinc Ions

The bioavailability of minerals, such as zinc and magnesium, has a significant impact on the fermentation process. These metal ions are known to influence the growth and metabolic activity of yeast, but there are few reports on their effects on lactic acid bacteria (LAB) metabolism during sour brewing. This study aimed to evaluate the influence of magnesium and zinc ions on the metabolism of Lactobacillus brevis WLP672 during the fermentation of brewers’ wort. We carried out lactic acid fermentations using wort with different mineral compositions: without supplementation; supplemented with magnesium at 60 mg/L and 120 mg/L; and supplemented with zinc at 0.4 mg/L and 2 mg/L. The concentration of organic acids, pH of the wort and carbohydrate use was determined during fermentation, while aroma compounds, real extract and ethanol were measured after the mixed fermentation. The addition of magnesium ions resulted in the pH of the fermenting wort decreasing more quickly, an increase in the level of L-lactic acid (after 48 h of fermentation) and increased concentrations of some volatile compounds. While zinc supplementation had a negative impact on the L. brevis strain, resulting in a decrease in the L-lactic acid content and a higher pH in the beer. We conclude that zinc supplementation is not recommended in sour beer production using L. brevis WLP672.

Novel microencapsulated yeast for the primary fermentation of green beer: kinetic behavior, volatiles and sensory profile

The development of innovative and more cost-effective approaches of making beer throughout continuous fermentation process remains a challenging problem, which is worthy of serious exploration. The current work focuses on the application of a commercial brewing yeast (S. cerevisiae Nottingham Ale), entrapped into chitosan-calcium alginate double layer microcapsules, for the production of a Pale Ale beer. During the primary alcoholic fermentation, the consumption rate of fermentable brewing sugars and dissolved O₂, estimated by the Gompertz equation, was halved in the beer obtained by encapsulated yeast in comparison with the free cell. The physical-chemical parameters of beer (i.e. pH, alcohol content, color and bitterness) were not remarkably affected by the different yeast-inoculating form. However, the volatile profiles identified by means of HS-SPME-GC-MS analysis, significantly differed in terms of terpenes, esters and alcohols content, thus proving that the yeast-inoculating form may typify the odor and flavor descriptors of the green beer.

Sourdough cultures as reservoirs of maltose-negative yeasts for low-alcohol beer brewing

De novo sourdough cultures were here assessed for their potential as sources of yeast strains for low-alcohol beer brewing. NGS analysis revealed an abundance of ascomycete yeasts, with some influence of grain type on fungal community composition. Ten different ascomycete yeast species were isolated from different sourdough types (including wheat, rye, and barley) and seven of these were screened for a number of brewing-relevant phenotypes. All seven were maltose-negative and produced less than 1% (v/v) alcohol from a 12 °Plato wort in initial fermentation trials. Strains were further screened for their bioflavouring potential (production of volatile aromas and phenolic notes, reduction of wort aldehydes), stress tolerance (temperature extremes, osmotic stress and ethanol tolerance) and flocculence. Based on these criteria, two species (Kazachstania servazzii and Pichia fermentans) were selected for 10 L-scale fermentation trials and sensory analysis of beers. The latter species was considered particularly suitable for production of low-alcohol wheat beers due to its production of the spice/clove aroma 4-vinylguaiacol, while the former showed potential for lager-style beers due to its clean flavour profile and tolerance to low temperature conditions.

Designing New Yeasts for Craft Brewing: When Natural Biodiversity Meets Biotechnology

Beer is a fermented beverage with a history as old as human civilization. Ales and lagers are by far the most common beers; however, diversification is becoming increasingly important in the brewing market and the brewers are continuously interested in improving and extending the range of products, especially in the craft brewery sector. Fermentation is one of the widest spaces for innovation in the brewing process. Besides Saccharomyces cerevisiae ale and Saccharomyces pastorianus lager strains conventionally used in macro-breweries, there is an increasing demand for novel yeast starter cultures tailored for producing beer styles with diversified aroma profiles. Recently, four genetic engineering-free approaches expanded the genetic background and the phenotypic biodiversity of brewing yeasts and allowed novel costumed-designed starter cultures to be developed: (1) the research for new performant S. cerevisiae yeasts from fermented foods alternative to beer; (2) the creation of synthetic hybrids between S. cerevisiae and Saccharomyces non-cerevisiae in order to mimic lager yeasts; (3) the exploitation of evolutionary engineering approaches; (4) the usage of non-Saccharomyces yeasts. Here, we summarized the pro and contra of these approaches and provided an overview on the most recent advances on how brewing yeast genome evolved and domestication took place. The resulting correlation maps between genotypes and relevant brewing phenotypes can assist and further improve the search for novel craft beer starter yeasts, enhancing the portfolio of diversified products offered to the final customer.

Bioprospecting for brewers: Exploiting natural diversity for naturally diverse beers

The burgeoning interest in archaic, traditional, and novel beer styles has coincided with a growing appreciation of the role of yeasts in determining beer character as well as a better understanding of the ecology and biogeography of yeasts. Multiple studies in recent years have highlighted the potential of wild Saccharomyces and non-Saccharomyces yeasts for production of beers with novel flavour profiles and other desirable properties. Yeasts isolated from spontaneously fermented beers as well as from other food systems (wine, bread, and kombucha) have shown promise for brewing application, and there is evidence that such cross-system transfers have occurred naturally in the past. We review here the available literature pertaining to the use of nonconventional yeasts in brewing, with a focus on the origins of these yeasts, including methods of isolation. Practical aspects of utilizing nondomesticated yeasts are discussed, and modern methods to facilitate discovery of yeasts with brewing potential are highlighted.