With the advances in the production of beer worldwide, more challenges arise each year in the search for new approaches to the development of distinctive beverages. Attempts to obtain products with ...more complex sensory characteristics have led experts and brewers to prospect for non-conventional yeasts, i.e., non-Saccharomyces yeasts that may provide a new range of perspectives in terms of techniques and approaches. Besides the widespread use of Dekkera/Brettanomyces for the production of sour beers, other species are emerging for presenting unusual metabolic features that include the production of fruity esters, and a distinctive enzymatic apparatus. Wickerhamomyces anomalus and Torulaspora delbrueckii stand out as the most promising yeasts in brewing processes. Such new tendencies in the use of non-Saccharomyces yeasts comprise the production of low-alcohol beers, functional beers, and bioflavoring approaches. This is a little explored field in brewing practice, still requiring extensive research with practical application. In this sense, this review aims to present the main points for the application of non-conventional yeasts in beer production, and thus contribute to future advances in the topic.
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•Potential use of non-Saccharomyces yeasts in brewing processes.•Different metabolic traits in non-conventional yeasts for brewing.•Influence of non-conventional yeasts on bioflavor, low alcohol and functional beers.
Dry hopping imparts distinct aromas but also a series of non-volatile compounds suspected of causing flavor and physical instability during beer storage. In this work, color, chill haze, total ...polyphenols, total flavanoids, and flavan-3-ol monomers (catechin and epicatechin) and oligomers (procyanidin dimers and trimers) were monitored in five commercial pale-colored Belgian dry-hopped beers over 24 months of storage at 20 °C in the dark. Fresh dry-hopped beers contained unusually high levels of flavan-3-ol monomers (up to 6.6 mg/L) and oligomers (up to 14.1 and 10.2 mg/L dimers and trimers, respectively). The increase in color intensity during storage (up to 6.4°EBC) correlated with fresh beer monomer levels, while the oligomer content correlated with chill haze formation (up to 25.7°EBC). The evolution of these two physical attributes also correlated with the level of total polyphenols in the fresh beers. In a pilot-scale production, kettle hopping was shown to impart either monomers (early) or oligomers (late), while dry hopping promoted efficient extraction of both monomers and dimers (extraction yields of 62 and 74%, respectively). Dry hopping thus plays an important role in color and chill haze increase.
Despite years of research, sensory deterioration during beer aging remains a challenge to brewing chemists. Therefore, sensorial and analytical tools to investigate aging flavors are required. This ...review aims to summarize the available analytical methods and to highlight the problems associated with addressing the flavor-stability of beer.
Carbonyls are the major contributors to the aroma of aged pale lager beer, which is especially susceptible to deterioration. They are formed via known pathways during storage, but, as recent research indicates, are mainly released from the bound-state during aging. However, most published studies are based on model systems, and thus the formation and breakdown parameters of these adducts are poorly understood. This concept has not been previously considered in previous forced-aging analysis.
Only weak parallels can be drawn between forced and natural aging. This is likely due to the different activation energies of the chemical processes responsible for aging, but may also be due to heat-promoted release of bound aldehydes. Thus, precursors and their binding parameters must be investigated to make appropriate technological adjustments to forced-aging experiments. In combination with sophisticated data analysis, the investigation of volatile indicators and non-volatile precursors can lead to more reliable predictions of flavor stability.
Light scattering in photopolymerizable ceramic suspensions affects the resolution of photopolymerization processing methods; it is necessary to predict the cure width and cure depth at a given energy ...dose for a suspension with a known composition. The volume fraction of ceramic powder in the suspension or the refractive index (RI) contrast between the ceramic powder and the liquid solution was varied, measuring the quasi-Beer–Lambert suspension properties. For these suspensions, the depth and width attenuation and the depth and width critical energy doses were determined. The volume fraction of powder has no effect on the broadening depth; the solids loading can be varied without concern for increased scattering within the suspension. The broadening depth decreases with the logarithm of RI contrast. Suspensions with a small RI contrast are able to cure deep, narrow features without broadening.
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