The Impact of Malt Derived Proteins on Beer Foam Quality. Part II: The Influence of Malt Foam-positive Proteins and Non-starch Polysaccharides on Beer Foam Quality

The Role of Gluten in Food Products and Dietary Restriction: Exploring the Potential for Restoring Immune Tolerance

Wheat is extensively utilized in various processed foods due to unique proteins forming from the gluten network. The gluten network in food undergoes morphological and molecular structural changes during food processing, affecting the final quality and digestibility of the food. The present review introduces the formation of the gluten network and the role of gluten in the key steps of the production of several typical food products such as bread, pasta, and beer. Also, it summarizes the factors that affect the digestibility of gluten, considering that different processing conditions probably affect its structure and properties, contributing to an in-depth understanding of the digestion of gluten by the human body under various circumstances. Nevertheless, consumption of gluten protein may lead to the development of celiac disease (CD). The best way is theoretically proposed to prevent and treat CD by the inducement of oral tolerance, an immune non-response system formed by the interaction of oral food antigens with the intestinal immune system. This review proposes the restoration of oral tolerance in CD patients through adjunctive dietary therapy via gluten-encapsulated/modified dietary polyphenols. It will reduce the dietary restriction of gluten and help patients achieve a comprehensive dietary intake by better understanding the interactions between gluten and food-derived active products like polyphenols.

Proteomics and Metabolomics Reveal that an Abundant α-Glucosidase Drives Sorghum Fermentability for Beer Brewing

Sorghum (Sorghum bicolor), a grass native to Africa, is a popular alternative to barley for brewing beer. The importance of sorghum to beer brewing is increasing because it is a naturally gluten-free cereal, and climate change is expected to cause a reduction in the production of barley over the coming decades. However, there are challenges associated with the use of sorghum instead of barley in beer brewing. Here, we used proteomics and metabolomics to gain insights into the sorghum brewing process to advise processes for efficient beer production from sorghum. We found that during malting, sorghum synthesizes the amylases and proteases necessary for brewing. Proteomics revealed that mashing with sorghum malt required higher temperatures than barley malt for efficient protein solubilization. Both α- and β-amylase were considerably less abundant in sorghum wort than in barley wort, correlating with lower maltose concentrations in sorghum wort. However, metabolomics revealed higher glucose concentrations in sorghum wort than in barley wort, consistent with the presence of an abundant α-glucosidase detected by proteomics in sorghum malt. Our results indicate that sorghum can be a viable grain for industrial fermented beverage production, but that its use requires careful process optimization for efficient production of fermentable wort and high-quality beer.

Quantitative TMT-based proteomics revealing host, dietary and microbial proteins in bovine faeces including barley serpin Z4, a prominent component in the head of beer

There has been little information about the proteome of bovine faeces or about the contribution to the faecal proteome of proteins from the host, the feed or the intestinal microbiome. Here, the bovine faecal proteome and the origin of its component proteins was assessed, while also determining the effect of treating barley, the major carbohydrate in the feed, with either ammonia (ATB) or sodium propionate (PTB) preservative. Healthy continental crossbreed steers were allocated to two groups and fed on either of the barley-based diets. Five faecal samples from each group were collected on Day 81 of the trial and analysed by quantitative proteomics using nLC-ESI-MS/MS after tandem mass tag labelling. In total, 281 bovine proteins, 199 barley proteins, 176 bacterial proteins and 190 archaeal proteins were identified in the faeces. Mucosal pentraxin, albumin and digestive enzymes were among bovine proteins identified. Serpin Z4 a protease inhibitor was the most abundant barley protein identified which is also found in barley-based beer, while numerous microbial proteins were identified, many originating bacteria from Clostridium, while Methanobrevibacter was the dominant archaeal genus. Thirty-nine proteins were differentially abundant between groups, the majority being more abundant in the PTB group compared to the ATB group. SIGNIFICANCE: Proteomic examination of faeces is becoming a valuable means to assess the health of the gastro-intestinal tract in several species, but knowledge on the proteins present in bovine faeces is limited. This investigation aimed to characterise the proteome of bovine faecal extracts in order to evaluate the potential for investigations of the proteome as a means to assess the health, disease and welfare of cattle in the future. The investigation was able to identify proteins in bovine faeces that had been (i) produced by the individual cattle, (ii) present in the barley-based feed eaten by the cattle or (iii) produced by bacteria and other microbes in the rumen or intestines. Bovine proteins identified included mucosal pentraxin, serum albumin and a variety of digestive enzymes. Barley proteins found in the faeces included serpin Z4, a protease inhibitor that is also found in beer having survived the brewing process. Bacterial and archaeal proteins in the faecal extracts were related to several pathways related to the metabolism of carbohydrates. The recognition of the range of proteins that can be identified in bovine faeces raises the possibility that non-invasive sample collection of this material could provide a novel diagnostic approach to cattle health and welfare.

Multi-Response Optimization of the Malting Process of an Italian Landrace of Rye (Secale cereale L.) Using Response Surface Methodology and Desirability Function Coupled with Genetic Algorithm

Rye is used in some applications in the food and beverage industry and for the preparation of functional foods. It is an interesting raw material in malting and brewing due to its characteristic contribution to the beer's color, turbidity, foam and aroma. The aim of this work was to optimize the micro-malting process of a rye landrace. The response surface methodology (RSM) was applied to study the influence of three malting parameters (germination time, germination temperature and degree of steeping) on the quality traits of malted rye. Long germination times at high temperatures resulted in an increase in the extract and Kolbach index. The model for the apparent attenuation limit showed a particular pattern, whereby time and temperature inversely influenced the response. The lowest viscosities were determined in the worts produced from highly modified malts. Optimization of the variables under study was achieved by means of a desirability function and a genetic algorithm. The two methodologies provided similar results. The best combination of parameters to optimize the malting process on the rye landrace under study was achieved at 6 days, 12 °C and 44 g/100 g.

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.

The Influence of Biomolecule Composition on Colloidal Beer Structure

Recent studies have revealed an interest in the composition of beer biomolecules as a colloidal system and their influence on the formation of beer taste. The purpose of this research was to establish biochemical interactions between the biomolecules of plant-based raw materials of beer in order to understand the overall structure of beer as a complex system of bound biomolecules. Generally accepted methods of analytical research in the field of brewing, biochemistry and proteomics were used to solve the research objectives. The studies allowed us to establish the relationship between the grain and plant-based raw materials used, as well as the processing technologies and biomolecular profiles of beer. The qualitative profile of the distribution of protein compounds as a framework for the formation of a colloidal system and the role of carbohydrate dextrins and phenol compounds are given. This article provides information about the presence of biogenic compounds in the structure of beer that positively affect the functioning of the body. A critical assessment of the influence of some parameters on the completeness of beer taste by biomolecules is given. Conclusion: the conducted analytical studies allowed us to confirm the hypothesis about the nitrogen structure of beer and the relationship of other biomolecules with protein substances, and to identify the main factors affecting the distribution of biomolecules by fractions.

Application of Mass Spectrometry-Based Proteomics to Barley Research

Barley (Hordeum vulgare) is the fourth most cultivated crop in the world in terms of production volume, and it is also the most important raw material of the malting and brewing industries. Barley belongs to the grass (Poaceae) family and plays an important role in food security and food safety for both humans and livestock. With the global population set to reach 9.7 billion by 2050, but with less available and/or suitable land for agriculture, the use of biotechnology tools in breeding programs are of considerable importance in the quest to meet the growing food gap. Proteomics as a member of the "omics" technologies has become popular for the investigation of proteins in cereal crops and particularly barley and its related products such as malt and beer. This technology has been applied to study how proteins in barley respond to adverse environmental conditions including abiotic and/or biotic stresses, how they are impacted during food processing including malting and brewing, and the presence of proteins implicated in celiac disease. Moreover, proteomics can be used in the future to inform breeding programs that aim to enhance the nutritional value and broaden the application of this crop in new food and beverage products. Mass spectrometry analysis is a valuable tool that, along with genomics and transcriptomics, can inform plant breeding strategies that aim to produce superior barley varieties. In this review, recent studies employing both qualitative and quantitative mass spectrometry approaches are explored with a focus on their application in cultivation, manufacturing, processing, quality, and the safety of barley and its related products.

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.

Foam-Resilient Distillation Processes—Influence of Pentosan and Thermal Energy Input on Foam Accumulation in Rye Mash Distillation

Foaming of mashes during distillation is a common problem encountered in spirit drink production. It has a negative impact on the purity of the final product. This research article presents the key aspects of foam accumulation in rye mashes during distillation. Foam accumulation was influenced by substrate characteristics and process parameters. The experiments showed that pentosan levels and thermal energy input were the crucial parameters for foam accumulation in rye mashes. Foam accumulation was significantly enhanced by higher pentosan levels, due to the higher viscosity imparted by pentosan. Hence, degradation of pentosans prior to distillation presents a way to reduce foam accumulation. In terms of thermal energy input, foam accumulation was significantly lower when the thermal energy input was reduced from 400 to 200 W/L. Substantial foaming only occurred in a narrow temperature range of 89.5 to 98.2 C. The results allowed for the first time to make recommendations to prevent problematic foam accumulation during distillation of rye mashes.

Optimization of Beer Brewing by Monitoring α-Amylase and β-Amylase Activities during Mashing

(1) Background: In the current highly competitive brewing industry, most breweries may benefit from a reduction in mashing time. In this study, a novel enzymatic assay format was used to investigate the activities of α-amylase and β-amylase during different mashing profiles, with the aim to use it as a tool for optimizing the production time of an existing industrial mashing process; (2) Methods: Lab-scale mashings with eight different time-temperature programs and two different pilot brews were analyzed in terms of enzymatic activity, sugar composition, alcohol by volume in the final beer, FAN and others; (3) Results: A 20-min reduction (out of an original 73-min mashing program) was achieved by selecting a temperature profile which maintained a higher enzymatic activity than the original, without affecting the wort sugar composition and fermentability, or the ethanol concentration and foam stability of the final beer. (4) Conclusions: A method is presented which can be used by breweries to optimize their mashing profiles based on monitoring α-amylase and β-amylase activities.

Development of a Rapid Method to Assess Beer Foamability Based on Relative Protein Content Using RoboBEER and Machine Learning Modeling

Foam-related parameters are associated with beer quality and dependent, among others, on the protein content. This study aimed to develop a machine learning (ML) model to predict the pattern and presence of 54 proteins. Triplicates of 24 beer samples were analyzed through proteomics. Furthermore, samples were analyzed using the RoboBEER to evaluate 15 physical parameters (color, foam, and bubbles), and a portable near-infrared (NIR) device. Proteins were grouped according to their molecular weight (MW), and a matrix was developed to assess only the significant correlations (p < 0.05) with the physical parameters. Two ML models were developed using the NIR (Model 1), and RoboBEER (Model 2) data as inputs to predict the relative quantification of 54 proteins. Proteins in the 0–20 kDa group were negatively correlated with the maximum volume of foam (MaxVol; r = −0.57) and total lifetime of foam (TLTF; r = −0.58), while those within 20–40 kDa had a positive correlation with MaxVol (r = 0.47) and TLTF (r = 0.47). Model 1 was not as accurate (testing r = 0.68; overall r = 0.89) as Model 2 (testing r = 0.90; overall r = 0.93), which may serve as a reliable and affordable method to incorporate the relative quantification of important proteins to explain beer quality.

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.

Posttranslational Modifications Drive Protein Stability to Control the Dynamic Beer Brewing Proteome

Mashing is a key step in beer brewing in which starch and proteins are solubilized from malted barley in a hot water extraction and digested to oligomaltose and free amino nitrogen. We used SWATH-MS to measure the abundance and site-specific modifications of proteins throughout a small-scale pale ale mash. Proteins extracted from the malt at low temperatures early in the mash decreased precipitously in abundance at higher temperatures late in the mash due to temperature/time-induced unfolding and aggregation. We validated these observations using experimental manipulation of time and temperature parameters in a microscale pale ale mash. Correlation analysis of temperature/time-dependent abundance showed that sequence and structure were the main features that controlled protein abundance profiles. Partial proteolysis by barley proteases was common early in the mash. The resulting proteolytically clipped proteins were particularly sensitive and were preferentially lost at high temperatures late in the mash, while intact proteins remained soluble. The beer brewing proteome is therefore driven by the interplay between protein solubilization and proteolysis, which are in turn determined by barley variety, growth conditions, and brewing process parameters.

Enzymatic Properties of endo-1,4-β-xylanase from Wheat Malt

BACKGROUND

Arabinoxylan (AX) is the main non-starch polysaccharide in wheat. Wheat malts are traditional raw materials for beer brewing. AX is divided into water-soluble arabinoxylan (WEAX) and waterinsoluble arabinoxylan (WUAX). In the mashing stage of beer production, WUAX in malt is degraded by arabinoxylanase to WEAX, which is further degraded to smaller molecules and retained in the final beer. The viscosity of WEAX is related to its molecular weight. WEAX with higher molecular weight and viscosity can increase viscosity and turbidity and reduce filtration speed of wort and beer; WEAX with moderate molecular weight and viscosity contributes to the foaming characteristics and foam stability, and promotes the taste and texture of a beer; WEAX with small molecular weight has the functions of anti-tumor and lowering blood pressure and is regarded as a prebiotic. Because WEAXs with different molecular weight and properties have different impacts on the beer brewing process and qualities of the final beer, it becomes more important to control the degradation of AX during the brewing process of a beer. Endo-1,4-β-xylanase (EC 3.2.1.8) is the most important AX degrading enzyme, which cleaves the β -xylosidic bond between two d-xylopyranosyl residues linked in β-(1,4). The study of enzymatic properties of endo-1,4-β-xylanase from wheat malt is very important for the rational formulation of the content and molecular weight of WEAX in wort and beer during the mashing procedure when using wheat malt as the main raw materials.

OBJECTIVE

In this article, our motivation is to study the enzymatic properties (including optimum pH and temperature, pH and temperature stability, the effect of inhibitors) of wheat malt endo-1,4-β-xylanase.

METHODS

In this article, we prepared crude enzyme according to the method of Guo with minor modifications. The endo-1,4-β-xylanase activity was determined according to the method of Biely in the previous report with minor modifications. The 0.5 mL crude enzyme sample was mixed with 0.5 mL 1 mg/mL 4-O-methyl-dglucurono- d-xylan dyed with Remazol Brilliant Blue R (RBBR-Xylan) solution, intensively mixed, and incubated at 40 °C for exactly 90 min. The reaction was stopped by precipitation using 2 mL absolute ethanol, and the reaction mixture was stirred acutely and placed at room temperature for 30 min. Then, the mixture was mixed again and centrifuged at 6000 g for 10 min. The supernatant was collected and the absorbance was measured at 590 nm. Absolute ethanol and RBBR-Xylan were added to the control tubes first, and after the reaction was completed, the crude enzyme sample was added. One unit of endo-1,4-β-xylanase was defined as at pH 5.5 and 40 °C liberate 1 μmol xylose equivalents in 1 min per g dry wheat malt.

RESULTS

The results showed that the optimal activity of endo-1,4-β-xylanase was achieved at pH 5.5-6.0, and the enzyme was extremely stable at pH 4.5, 5.5 and 6.5 after incubation for 30, 50 and 60 min, respectively. The optimal temperature was 40-45 °C and the deactivation temperature was 75 °C. Endo-1,4-β-xylanase was stable at 20 °C and 40 °C; the stability was slightly decreased at 50 °C and rapidly decreased at 55 °C. The enzyme activity was mildly inhibited by K+, Na+, and Pb2+, moderately inhibited by Ca2+, Mg2+ and Mn2+ and severely inhibited by Cu2+, Ag+ and EDTA.

CONCLUSION

We have got the enzymatic properties of endo-1,4-β-xylanase from wheat malt, so during wort mashing, we could apply this research result to carry out the rational formulation of the content and molecular weight of WEAX in wort and beer during the mashing procedure when using wheat malt as the main raw materials. Expected to solve the technical problems such as high viscosity, slow filtration speed and so on, but also highlight the typical flavors of WEAX such as rich and persistent foam and mellow texture during the brewing process of a beer.

Batch anaerobic digestion of deproteinated malt whisky pot ale using different source inocula

A novel process has been developed for the selective removal of protein from pot ale with recovered protein holding potential as a value-added by-product for the whisky industry. The purpose of this work was to assess the effect of deproteination on pot ale physicochemical characterisation and anaerobic digestion (AD) treatment. Pot ales were taken from five malt whisky distilleries and tested untreated, after centrifugation/filtration and after deproteination at laboratory or pilot scale. At laboratory scale, the deproteination process removed around 20% of total chemical oxygen demand (tCOD) from untreated pot ale and at least 30% dissolved copper from centrifuged pot ale. Biochemical methane potential of untreated, filtered and deproteinated pot ale obtained at pilot scale has been determined using two types of inocula from different source. Average methane yield values of 554±67, 586±24 and 501±23 Nl CH₄ kg^-1 VS were obtained for untreated, filtered and deproteinated pot ale respectively. A significant difference in methane yield was only observed for untreated pot ale using the two types of inocula. Specifically, when using a non-adapted inoculum untreated pot ale biogas yield was significant lower suggesting inhibition of the AD process. As no significant differences were found for treated pot ale (filtered and deproteinated) with the two inocula it suggests, deproteination may have a positive effect on AD start-up. The results present a clear case for continuation of this work and evaluating the effect on continuous AD.

Comparative analysis of the effect of protein Z4 from barley malt and recombinant Pichia pastoris on beer foam stability: Role of N-glycosylation and glycation

This study aimed to elaborate the effect of N-glycosylation and glycation of protein Z₄ from barley malt and recombinant Pichia pastoris on beer foam stability. The malt protein Z₄ and recombinant protein Z₄ showed similar N-glycosylation patterns while recombinant protein Z₄ was glycosylated at a higher degree. In the simulated mashing and boiling, malt protein Z₄ and deglycosylated malt protein Z₄ preferred to glycate with glucose and maltose while recombinant protein Z₄ and deglycosylated recombinant protein Z₄ showed preference towards fructose. The addition of protein Z₄ and protein Z₄-saccharide complexes in finished beer showed that the addition of glycosylated protein Z₄ only slightly enhanced the beer foam stability while the addition of glycated protein Z₄ and protein Z₄ with both glycation and glycosylation could significantly increase the beer foam stability. Therefore, glycation instead of N-glycosylation of protein Z₄ played important roles in maintaining beer foam stability.

Variation in barley (1 → 3, 1 → 4)-β-glucan endohydrolases reveals novel allozymes with increased thermostability

Novel barley (1 → 3, 1 → 4)-β-glucan endohydrolases with increased thermostability. Rapid and reliable degradation of (1 → 3, 1 → 4)-β-glucan to produce low viscosity wort is an essential requirement for malting barley. The (1 → 3, 1 → 4)-β-glucan endohyrolases are responsible for the primary hydrolysis of cell wall β-glucan. The variation in β-glucanase genes HvGlb1 and HvGlb2 that encode EI and EII, respectively, were examined in elite and exotic germplasm. Six EI and 14 EII allozymes were identified, and significant variation was found in β-glucanase from Hordeum vulgare ssp. spontaneum (wild barley), the progenitor of modern cultivated barley. Allozymes were examined using prediction methods; the change in Gibbs free energy of the identified amino acid substitutions to predict changes in enzyme stability and homology modelling to examine the structure of the novel allozymes using the existing solved EII structure. Two EI and four EII allozymes in wild barley accessions were predicted to have improved barley β-glucanase thermostability. One novel EII candidate was identified in existing backcross lines with contrasting HvGlb2 alleles from wild barley and cv Flagship. The contrasting alleles in selected near isogenic lines were examined in β-glucanase thermostability analyses. The EII from wild barley exhibited a significant increase in β-glucanase thermostability conferred by the novel HvGlb2 allele. Increased β-glucanase thermostability is heritable and candidates identified in wild barley could improve malting and brewing quality in new varieties.

Novel Barley (1→3,1→4)-β-Glucan Endohydrolase Alleles Confer Increased Enzyme Thermostability

Barley (1→3,1→4)-β-glucan endohydrolases (β-glucanases; EI and EII) are primarily responsible for hydrolyzing high molecular weight (1→3,1→4)-β-glucans (β-glucan) during germination. Incomplete endosperm modification during malting results in residual β-glucan that can contribute to increased wort viscosity and beer chill haze. Four newly identified forms of EI and EII and the reference enzymes EI-a and EII-a were expressed in Escherichia coli, and the recombinant proteins were characterized for enzyme kinetics and thermostability. EI and EII variants that exhibited higher residual β-glucanase activity than EI-a and EII-a after heat treatment also exhibited increased substrate affinity and decreased turnover rates. The novel EII-l form exhibited significantly increased thermostability compared with the reference EII-a when activity was measured at elevated temperature. EII-l exhibited a T₅₀ value, which indicates the temperature at which 50% of β-glucanase activity remains, 1.3 °C higher than that of EII-a. The irreversible thermal inactivation difference between EII-a and EII-l after 5 min of heat treatment at 56 °C was 11.9%. The functional significance of the three amino acid differences between EII-a and EII-l was examined by making combinatorial mutations in EII-a using site-directed mutagenesis. The S20G and D284E amino acid substitutions were shown to be responsible for the increase in EII-1 thermostability.