Comparison of the hydrocolloids application efficiency for stabilizing the foam of beer

Subject of research: technology of high gravity brewing, developed to improve production efficiency and reduce energy consumption. This technology has a wide range of benefits, from improving process economics to reducing environmental impact. Investigated problem: despite the presence of significant advantages, there are a number of problems in the technology of high gravity brewing that need to be solved. The main problem is to reduce the foam stability of the resulting beer, which, together with the appearance, aroma and taste, is the most important attributes of the quality of the beverage for the consumer. The stability and texture of the foam depend, among other things, on the quality of grain and hop raw materials, and the course of technological processes. Elevated levels of key malt proteins (LTP1, Z4 and Z7) and hop α-acids have a positive effect on foam quality. Yeast protease A has a negative effect. Yeast secretes this enzyme to a greater extent during fermentation of high gravity wort, which may be one of the reasons for the decrease in foam stability in high gravity brewing. High molecular weight a- and b-glucans with hydrophilic properties can play an important role in foam stabilization. They increase the viscosity of the liquid, slow down its drainage from the foam segments and thereby increase the foam retention. Main scientific results: the effect of hydrocolloids (highly methoxylated pectin, carboxymethyl cellulose, xanthan gum, guar gum, a mixture of xanthan and guar gum) on foam performance and beer filtration rate was investigated. The advantages of pectin as an additive allowing to stabilize beer foam, in particular, in high gravity - brewing, have been established. The recommended dosage of the additive is 0.4-1 g/hl. Highly methoxylated pectin is a good alternative to the currently widespread use of propylene glycol alginate. The area of practical implementation of the research results: brewing companies. Innovative technological product: highly methoxylated pectin as a stabilizing additive for beer foam. Scope of application of the innovative technological product: the use of highly methoxylated pectin as additives that stabilize beer foam, in particular in high gravity brewing.

Interaction of proteins and amino acids with iso-α-acids during wort preparation in the brewhouse

This paper investigates the binding behavior of iso-α-acids from hops on free wort amino acids and proteins concerning the wort production process in breweries. The studies were carried out with different amino acids, bovine serum albumin and wort. To identify the nature of reaction between iso-α-acids and these substances, analyses of free amino nitrogen, HPLC and isothermal titration calorimetry were performed. According to the results, the iso-α-acids do not form covalent bonds with free amino acids of wort. However, iso-α-acids, especially isohumulone and isoadhumulone, form ionic bonds with wort proteins. A distinction must be made between proteins that are present in the hot trub, and those that are still dissolved in the hot wort. Proteins that are already coagulated and precipitated no longer react with iso-α-acids. Future experiments will investigate whether the established ionic bonds between iso-α-acids and proteins from the wort preparation process are maintained during fermentation until the finished beer or beer foam. If this is the case, which is induced by the experiments, there is a measurable loss of iso-α-acids in the hot wort, but at the same time, a gain for the later beer foam retention, as the iso-α-acids will stabilize it.

Complementing Digital Image Analysis and Laser Distance Meter in Beer Foam Stability Determination

The aim of this research is to investigate the possibility of applying a laser distance meter (LDM) as a complementary measurement method to image analysis during beer foam stability monitoring. The basic optical property of foam, i.e., its high reflectivity, is the main reason for using LDM. LDM measurements provide relatively precise information on foam height, even in the presence of lacing, and provide information as to when foam is no longer visible on the surface of the beer. Sixteen different commercially available lager beers were subjected to analysis. A camera and LDM display recorded the foam behavior; the LDM display which was placed close to the monitored beer glass. Measurements obtained by the image analysis of videos provided by the visual camera were comparable to those obtained independently by LDM. However, due to lacing, image analysis could not accurately detect foam disappearance. On the other hand, LDM measurements accurately detected the moment of foam disappearance since the measurements would have significantly higher values due to multiple reflections in the glass.

Molecular Characterization of Arabinoxylan from Wheat Beer, Beer Foam and Defoamed Beer

This research was to explore the distribution and some molecular characterization of arabinoxylan in wheat beer (B), beer foam (BF) and defoamed beer (DB) because of the crucial influences of arabinoxylan on wheat beer and its foam. The purified arabinoxylan from B, BF, and DB were fractionated by ethanol of 50%, 67%, 75%, and 80%. The monosaccharide composition, substitution degree (Ara/Xyl ratio, A/X), and average degrees of polymerization (avDP) of arabinoxylan were investigated. Molecular weight and microstructure were also involved in this study by GPC-LLS and SEM, respectively. Under the same ethanol concentration, the arabinoxylan content in the BF was higher than the other two, respectively, and it was precipitated in BF fraction with 50% ethanol which accounted for 80.84% of the total polysaccharides. Meanwhile, the greatest substitution degree (A/X) and highest value of avDP of the arabinoxylan was found in all beer foam fractions regardless of the concentration of ethanol used. The average degrees of polymerization (avDP) of arabinoxylan displayed a significant difference (p < 0.05) among B, BF, and DB. Furthermore, arabinoxylan presented varied microstructure with irregular lamellas and spherical structures and the weight-average molecular weight (Mw) of arabinoxylan showed the lowest values in BF, while the largest values were shown in DB. Therefore, arabinoxylan was more accumulated in beer foam, especially in 50% ethanol, characterised by greater value of A/X and avDP, as well as lower Mw. It was suggested that the arabinoxylan played important roles in maintaining wheat beer foam characteristics.

A Review on the Source of Lipids and Their Interactions during Beer Fermentation that Affect Beer Quality

The presence of lipids in wort and beer are important due to their influence on yeast metabolism and beer quality. Barley lipids have long been considered to have adverse effects on beer quality where some long-chain fatty acids are associated with high flavour potential. In addition, beer foam stability can be influenced by the concentration of lipids as well as other factors such as hop acids (e.g., iso-α-acids), proteins, polysaccharides and the presence of metal ions (e.g., nickel). Lipids can also influence yeast protease activity as well as the production of ethanol. This review provides an overview of the effect of climate change on the chemical composition of barley in relation to lipids and the influence of lipids in the process of this raw material in order to produce beer.

Beer foam decay: effect of glass surface quality and CO2 content

The effect of beer glass surface quality and CO2 content in beer on foam decay was investigated using our experimental method. The effect of beer glass surface quality on foam decay was experimentally investigated for: i) cold & clean glass surface, ii) warm & clean glass surface, iii) cold & greasy glass surface, and iv) cold & dusty glass surface. The fastest foam decay was observed for greasy glass surface. It was found that increasing CO2 content in beer: i) the liquid content in the foam decreases, and ii) the foam breaks down faster. The foam decay and growth kinetics of foam-liquid interface were statistically treated using own models.