Wine Saccharomyces Yeasts for Beer Fermentation

Multiple studies in recent years have shown the potential of Saccharomyces wild yeasts to produce craft beers with new flavour profiles and other desirable properties. Yeasts isolated from food (wine, bread, kombucha…) have shown potential promise for application in brewing. The aim of this study is to evaluate the ability of 141 Saccharomyces yeast strains isolated from the Madrilenian agriculture (from grapes, must, wine, vineyard, and cellars) to produce a novel ale beer. Fermentation activity of the strains was compared against the commercial strain Saccharomyces cerevisiae Safale S-04. In addition to the other aspects such as melatonin production, thirty-three volatile compounds belonging to higher alcohols, esters, aldehydes/cetones, acids, lactones and phenolic groups, were analysed by GC for selection of the strains. Ten strains were finally chosen, among which the most relevant was the strain G 520 showing a higher production of esters, higher alcohols and acids compared with S-04. The apparent attenuation for this strain was lower than commercial strain, which translates into more residual sugars. Furthermore, G 520 was more capable of producing significantly higher amounts of melatonin studied by HPLC, as well as showing a higher antioxidant capacity. Consumer study showed that G 520 strain could be used to produce a potential beer that has a place in the current market.

Norwegian Kveik brewing yeasts are adapted to higher temperatures and produce fewer off-flavours under heat stress than commercial Saccharomyces cerevisiae American Ale yeast

Norwegian kveik are a recently described family of domesticated Saccharomyces cerevisiae brewing yeasts used by farmhouse brewers in western Norway for generations to produce traditional Norwegian farmhouse ale. Kveik ale yeasts have been domesticated by farmhouse brewers through serial repitching of the yeast in warm wort (>30°C) punctuated by long periods of dry storage. Kveik yeasts are alcohol tolerant, flocculant, capable of utilizing maltose/maltotriose, phenolic off flavour negative, and exhibit elevated thermotolerance when compared to other modern brewer's yeasts belonging to the 'Beer 1' clade. However, the optimal fermentation and growth temperatures (Topt) for kveik ale yeasts and the influence of fermentation temperature of the production of flavour-active metabolites like fusel alcohols and sulfur compounds (H2S, SO2) are not known. Here we show that kveik ale yeasts have an elevated optimal fermentation temperature (Topt) when compared to commercial American Ale yeast (SafAle™ US-05) and that they produce fewer off-flavours at high temperatures (>30°C) when compared to commercial American Ale yeasts. The tested kveik yeasts show significantly higher maximum fermentation rates than American Ale yeast not only at elevated temperatures (>30°C), but also at 'typical' ale fermentation temperatures (20°C-25°C). Finally, we demonstrate that kveik ale yeasts are heterogeneous in their Topt and that they attenuate standard wort robustly above their Topt unlike our control American Ale yeast which showed very poor apparent attenuation in our standard wort at temperatures >> Topt. Our results provide further support that kveik yeasts may possess favourable fermentation kinetics and sensory properties compared to American Ale yeasts. The observations here provide a roadmap for brewers to fine tune their commercial fermentations using kveik ale yeasts for optimal performance and/or flavour impact.

Revisit Seismic Attenuation Attributes: Influences of the Spectral Balancing Operation on Seismic Attenuation Analysis

Seismic attenuation analysis is important for seismic processing and quantitative interpretation. Nevertheless, the classic quality factor estimation methods make certain assumptions that may be invalid for a given geologic target and seismic volume. For this reason, seismic attenuation attribute analysis, which reduces some of the theoretical assumptions, can serve as a practical alternative in apparent attenuation characterization. Unfortunately, most of the published literature defines seismic attenuation attributes based on a specific source wavelet assumption, such as the Ricker wavelet, rather than wavelets that exhibit a relatively flat spectrum produced by modern data processing workflows. One of the most common processing steps is to spectrally balance the data either explicitly in the frequency domain, or implicitly through wavelet shaping deconvolution. If the post-stack seismic data have gone through the spectral balancing/whitening to improve the seismic resolution, the wavelet would exhibit a flat spectrum instead of a Ricker or Gaussian shape. We address the influence of the spectral balancing on seismic attenuation analysis. Our mathematical analysis shows that attenuation attributes are still effective for the post-stack seismic data after certain types of spectral balancing. More importantly, this analysis explains why seismic attenuation attributes work for real seismic applications with common seismic processing procedures. Synthetic and field data examples validate our conclusions.

Online measurement of floc size, viscosity, and consistency of cellulose microfibril suspensions with optical coherence tomography

In this study, cellulose microfibril (CMF) suspensions were imaged during pipe flow at consistencies of 0.4%, 1.0%, and 1.6% with optical coherence tomography (OCT) to obtain images of the structure and the local velocity of the suspension. The viscosities obtained by combining pressure loss measurement with the OCT velocity data showed typical shear thinning behavior and were in excellent agreement with viscosities obtained with ultrasound velocity profiling. The structural OCT images were used to calculate the radial and the axial floc sizes of the suspension. A fit of power law to the geometrical floc size–shear stress data gave the same power law index for all consistencies, suggesting that floc rupture dynamics is independent of consistency. The dependence of viscosity and floc size on shear stress was similar, indicating that the shear thinning behavior of CMF suspensions is closely related to the rupture dynamics of flocs. The results also showed that an apparent attenuation coefficient of the OCT signal can be used to determine the consistency of CMF suspensions.

Balling's attenuation theory and beer composition calculator

This article deals with calculation possibilities and the control of basic parameters of beer on the basis of knowledge of two parameters. The importance of this method increases with the development of craft beer production in our country (mini-breweries, home brewing). The calculations are based on Balling's equations, alcohol factors and attenuation quotients, which have been published unchanged since at least 1876. In Balling's time, they were used to determine an extract with a specific gravities of 17.5 °C/17.5 °C. In current brewing, specific gravities of 20 °C/20 °C are used. For this reason, new alcohol factors of apparent attenuation were derived, and based on linear regression, regression coefficients of the dependence of the alcohol factor of apparent attenuation on the extract in original wort were calculated. Some variants of calculations based on two input parameters were incorporated into the beer composition calculator using formulas that replace extract and alcohol tables. The accuracy of the results from the calculator was checked with analyses from the Anton Paar automatic analyzer and with analyses obtained by the distillation method. The calculator is available at www.balling.cz.

Brewing Characteristics of the Maltotriose-Positive Yeast Zygotorulaspora florentina Isolated from Oak

The use of wild yeasts in fermentation is becoming a viable option for the differentiation of beers. To achieve good fermentation rates and alcohol yields, however, such yeasts must have the ability to utilize the wort sugars maltose and maltotriose, a relatively rare trait amongst non-domesticated yeasts. Zygotorulaspora florentina is a species with the ability to utilize both sugars, and was evaluated here with respect to its brewing potential. The strain studied (VTT C-201041) was isolated from bark of an oak tree (Quercus robur) in Espoo, Finland. The fermentation performance of the strain was compared to that of two ale yeasts as well as the species type strain (VTT C-94199). Both Z. florentina strains fermented wort efficiently (apparent attenuation levels >77%). While the type strain had the highest yield, the Finnish strain produced more volatile aroma compounds. The species is capable of decarboxylating ferulic acid to produce the spice/clove-like compound 4-vinylguaiacol, which was present in beers at a concentration above the typical flavor threshold. The characteristic flavor of 4-vinylguaiacol was not however perceptible in taste trials, possibly due to the masking effect of other compounds. The potential of this species for industrial application is discussed, particularly in relation to its apparent ethanol sensitivity.

Spectral attenuation of ocean waves in pack ice and its application in calibrating viscoelastic wave-in-ice models

We investigate a case of ocean waves through a pack ice cover captured by Sentinel-1A synthetic aperture radar (SAR) on 12 October 2015 in the Beaufort Sea. The study domain is 400 km by 300 km, adjacent to a marginal ice zone (MIZ). The wave spectra in this domain were reported in a previous study (Stopa et al., 2018b). In that study, the authors divided the domain into two regions delineated by the first appearance of leads (FAL) and reported a clear change of wave attenuation of the total energy between the two regions. In the present study, we use the same dataset to study the spectral attenuation in the domain. According to the quality of SAR-retrieved wave spectrum, we focus on a range of wave numbers corresponding to 9–15 s waves from the open-water dispersion relation. We first determine the apparent attenuation rates of each wave number by pairing the wave spectra from different locations. These attenuation rates slightly increase with increasing wave number before the FAL and become lower and more uniform against wave number in thicker ice after the FAL. The spectral attenuation due to the ice effect is then extracted from the measured apparent attenuation and used to calibrate two viscoelastic wave-in-ice models. For the Wang and Shen (2010b) model, the calibrated equivalent shear modulus and viscosity of the pack ice are roughly 1 order of magnitude greater than that in grease and pancake ice reported in Cheng et al. (2017). These parameters obtained for the extended Fox and Squire model are much greater, as found in Mosig et al. (2015) using data from the Antarctic MIZ. This study shows a promising way of using remote-sensing data with large spatial coverage to conduct model calibration for various types of ice cover.Highlights. Three key points: The spatial distribution of wave number and spectral attenuation in pack ice are analyzed from SAR-retrieved surface wave spectra. The spectral attenuation rate of 9–15 s waves varies around 10−5 m2 s−1, with lower values in thicker semicontinuous ice fields with leads. The calibrated viscoelastic parameters are greater than those found in pancake ice.

The relative contributions of scattering and viscoelasticity to the attenuation of S waves in Earth's mantle

The relative contributions of scattering and viscoelastic attenuation to the apparent attenuation of seismic body waves are estimated from synthetic and observed S waves multiply reflected from Earth's surface and the core–mantle boundary. The synthetic seismograms include the effects of viscoelasticity and scattering from small-scale heterogeneity predicted from both global tomography and from thermodynamic models of mantle heterogeneity that have been verified from amplitude coherence measurements of body waves observed at dense arrays. Assuming thermodynamic models provide an estimate of the maximum plausible power of heterogeneity measured by elastic velocity and density fluctuations, we predict a maximum scattering contribution of 43 % to the total measured attenuation of mantle S waves having a dominant frequency of 0.05 Hz. The contributions of scattering in the upper and lower mantle to the total apparent attenuation are estimated to be roughly equal. The relative strength of the coda surrounding observed ScSn waves from deep focus earthquakes is not consistent with a mantle having zero intrinsic attenuation.