The effect of barley to wheat ratio in malt blends on protein composition and physicochemical characteristics of wort and beer

The present work explored the effect of barley to wheat ratio in malt blends on protein composition and physicochemical characteristics of wort and beer. Results illustrated that the addition of wheat malt can significantly improve the soluble protein of wort and the final beer, and it can provide more > 2.2 kDa protein in final beer, which is mainly derived from the raw wheat malt, but also including some protein produced in the fermentation process, such as some protein between 29 and 66.4 kDa. Though the content of > 15 kDa protein was relatively lower than the protein whose molecular weight was < 15 kDa, but it had important effects on total nitrogen, total water-soluble protein, free amino nitrogen, chromaticity, and viscosity of final beer. The addition of wheat malt significantly improved the concentration of 2.2-15 and > 15 kDa protein, but higher percentage of addition ratio can decrease the foam stability of the beer. PRACTICAL APPLICATION: This findings can reasonably control the protein content and types of wheat beer, improve the quality of wheat beer, solve the key technological problems, and expand and popularize the application of wheat in beer industry.

Suitability of Selected Winter Cultivars of Wheat from Production of Wheat Beer

The study investigated the feasibility of three winter cultivars of wheat – Elixer, Rockefeller and Gimantis, for production of wheat beer. Reference samples were produced from commercially available wheat malt. The findings showed the beer produced from commercially available wheat malt presented the best sensory and physicochemical parameters, including real final fermentation of 70.11%. The results related to the investigated wheat cultivars showed good quality properties in the beer produced from malts obtained from Gimantis cultivar (content of CO2 – 0.58%), and from Rockefeller cultivar (alcohol content - 4.62% v/v). A similar relationship was observed in the sensory assessment. The findings related to beer produced from malt of Elixer wheat cultivar showed relatively low effectiveness of the production process (69.7%) and final beer fermentation (65.52%), and at the same time high contents of polyphenols (210 mg/dm3) and antioxidant activity. Wheat malts produced from Gimantis and Rockefeller cultivars can effectively be used as a raw material in beer production; on the other hand, malt from Elixer cultivar, found with higher antioxidant contents, may be used as an additive to be applied in a small quantity in the mashing process in order to enhance the beer in terms of its potential health benefits.

Quality and Pro-Healthy Properties of Belgian Witbier-Style Beers Relative to the Cultivar of Winter Wheat and Raw Materials Used

Unmalted wheat grain and barley malt are the basic materials used in the production of Belgian wheat beers known as Witbier. A change in the ingredients defined in the recipe, by which part of the unmalted wheat is replaced with wheat malt, can positively affect the quality of the beverage produced. The purpose of the study was to brew Witbier-style beers made from four cultivars of winter wheat, with a 50% share of unmalted wheat and barley malt as well as Witbier-style beers made from four wheat cultivars, where 25% of unmalted wheat was replaced with wheat malt. Physicochemical and sensory analyzes showed mild differences in the quality of the beer products, more specifically higher alcohol content (by 11.33%) were found in beers made without the addition of wheat malt, while higher sensory attractiveness and 17.13% higher total polyphenol content were identified in beers enhanced with wheat malt. Phenolic compounds were identified using UPLC-PDA-MS/MS. The highest flavanol content, including kaempferol 3-O-rhamnoside-7-O-pentoside, was found in beers produced using wheat grains of the ‘Elixer’ cultivar, whether or not wheat malt was added; the values were 1.31 mg/L in E50 beer, and 1.39 mg/L in E25 beer. The same beer samples with the highest antioxidant and antiradical activity were found (in E25 beer, 2.35 mmol TE/L, and in E50 beer, 2.12 mmol Fe^2+/L). The present findings show that the investigated wheat cultivars may be used in beer production, whereas replacing part of unmalted wheat with wheat malt can improve the sensory profile of the beer produced.

Effect of an endo-1,4-β-xylanase from wheat malt on water-unextractable arabinoxylan derived from wheat

BACKGROUND

Non-starch polysaccharides in wheat are dominated by arabinoxylan (AX). Endo-1,4-β-xylanase (EC 3.2.1.8) is the most important enzyme for degrading AX. This paper investigated the ability of endo-1,4-β-xylanase extracted from wheat malt to degrade non-water-extractable wheat-derived arabinoxylan (WUAX).

RESULTS

The enzyme was observed to break down wheat-derived WUAX effectively, substantially increasing the concentration of water-extractable arabinoxylan (WEAX) in the system for up to 6 h. A considerable quantity of arabinose xylooligosaccharide (AXOS) was also produced, suggesting that the enzyme could produce oligosaccharides too. The molecular weight of the product WEAX was between 23 and 27 kDa and the content of oligosaccharides changed with degradation time. This suggests that endo-1,4-β-xylanase can not only degrade WUAX into WEAX and xylooligosaccharides but can also degrade the xylooligosaccharides with larger molecular weights into xylobiose and xylotriose. The viscosity of the degradation product increased significantly in the first 2 h, then decreased with longer degradation times. The concentration of WEAX in the reaction system increased throughout the reaction but at gradually lower rates, indicating that the endo-1,4-β-xylanase degraded WEAX better than it degraded WUAX. Rheological tests showed that solutions prepared from the WEAX that was produced had properties of a pseudoplastic fluid.

CONCLUSION

The results showed that the wheat malt endo-1,4-β-xylanase, which we had previously tested on WEAX, was also effective in degrading wheat-derived WUAX. This study can therefore provide a theoretical basis for the subsequent role of the enzyme in other sources of xylan, and provide guidance for the quality control of beer in the brewing process. © 2021 Society of Chemical Industry.

Effect of malting process duration on malting losses and quality of wheat malts

The study assesses impact of malting process duration on malting losses and quality of malts obtained from three varieties of winter wheat, i.e., Elixer, Rockefeller and Gimantis. The findings show that increased duration of the malting process (from 4 to 7 days) corresponded to greater total weight loss, with the most significant differences observed between 5-day and 6-day wheat malts. The qualitative analysis of the malts was carried out in accordance with EBC methodology. The assessments showed that the 5-day long malting process applied to the relevant wheat varieties resulted in production of high-quality malt with optimum malting losses observed in the case of Elixer and Rockefeller varieties. Slightly higher malting losses were identified in the case of Gimantis, and the malt obtained from this variety had very high contents of soluble protein (on average 5.34% d.m.) and Kolbach Index (average of 50.49%), which reflects high proteolytic activity during the grain malting process and a need to modify the malting process for this variety.

Relationship between the index of protein modification (Kolbach index) and degradation of macromolecules in wheat malt

Kolbach index (KI) is an important index to evaluate the qualities of malt, which will affect protein molecular composition, enzyme activity, and other macromolecules degradation during wheat malting. In this paper, the relationship between wheat (Triticum aestivum L.) malts KI and the (i) characterization of albumins, globulins, gliadins, and glutenins and their hydrolysis and (ii) the enzymatic breakdown of starch and arabinoxylans during malting were studied. As malt KI values increased, all fractions of glutenins and gliadins were extensively hydrolyzed. The higher Mw globulins (36.6 to 70.8 kDa) were also increasingly degraded at higher KI values, but the concentration of smaller globulin fractions (14.9 to 35.0 kDa) had increased significantly. As for albumins, although their overall concentration had increased as KI increased, changes in the concentration of individual albumin fractions was more complex. While there were significant increases in the concentration of some new albumin proteins (43.8 and 84.4 kDa), the concentration of some albumins decreased (21.1 to 64.3 kDa), and some fractions had completely disappeared (28.8 and 64.3 kDa). Following mashing, the hydrophobicity of the worts had decreased significantly at higher KI values. At malt KI values between 39.5% and 42.7%, the enzymatic activity was at its highest, the degradation of starch was adequate and stable, and the concentration of water-soluble arabinoxylans was optimal. A KI value of about 39.5% to 42.7% was therefore considered optimal for the production of wheat malts with superior quality attributes. PRACTICAL APPLICATION: The findings from this study will be valuable to beer companies; a more precise control of the malting and brewing parameters, fundamental for the production of high-quality wheat malts and wheat beer, can be achieved.

Technological Assessment of Winter Cultivar of Common Wheat (Triticum aestivum L.) and Winter Barley (Hordeum vulgare L.) for Pale Malt Production

The study was designed to assess technological quality of grains from two wheat cultivars (Elixer and Rockefeller), as well as one cultivar of winter (Joy) and one cultivar of spring barley (Irina), and to carry out the malting process at temperature of 15°C for 5 days. Malt analyses were carried out in accordance with the ECB Methods. The wheat malts were found with lower Kolbach index, and high viscosity was identified in wort obtained from wheat. The findings related to the wheat malts showed better quality parameters in Elixer variety compared to Rockefeller variety. Elixer wheat malt had higher diastatic power (427.03 WK) and lower extractivity (81.85%) compared to Joy barley malt (376.12 WK and 85.79%). Laboratory tests assessing the malts and wort showed that winter barley grain has high malting quality and can be used without modifications in the malting and mashing processes in brewing industry. It is necessary to conduct further research focusing on cultivation, agricultural techniques and technologies applied in wheat farming, in order to obtain cultivars which can be used to produce high quality malts.

Purification, Identification, and Characterization of an Endo-1,4-β-Xylanase from Wheat Malt

In this study, an endo-1,4-β-xylanase was purified from wheat malt following the procedures of ammonium sulfate precipitation, cation-exchange chromatography, and two-step anion-exchange chromatography. The purified endo-1,4-β-xylanase had a specific activity of 3.94 u/mg, demonstrating a weight average molecular weight (Mw) of approximately 58,000 Da. After LC-MS/MS (Liquid chromatography-tandem mass spectrometry) identification, the purified enzyme had the highest matching degree with a GH10 (Glycoside Hydrolase 10) domain-containing protein from wheat, there were 23 match peptides with a score above the threshold and the prot-cover was 45.5%. The resulting purified enzyme was used to investigate its degradation ability on high viscosity wheat-derived water-extractable arabinoxylan (WEAX). Degradation experiments confirmed that the purified enzyme was a true endo-acting enzyme, which could degrade large WEAX into smaller WEAX. The average degree of polymerization (avDP) and the viscosity of WEAX decreased with the increasing reaction time. The enzyme could degrade a small amount of WEAX into arabinoxylan-oligosaccharides (AXOS) with a degree of polymerization of 2-6, but no monosaccharide was produced. The degradation occurred rapidly in the first 3.5 h and decreased with the further prolongation of reaction time.