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PH in brewing: An overview
... As a consequence, at the brewhouse level, pH range will impact extract yield, fermentability, wort filtration, total and free amino nitrogen (FAN) levels and color intensity. [4] Mash acidification, achieved through the addition of calcium salts (precipitating phosphates) or alternative methods, accelerates the degradation of starch, enhances the activities of carbohydrases and the proteolytic enzymes, leading to increased values of total soluble nitrogen (TSN) and FAN as well as a reduction in wort color. [1,2,5] Besides addition of calcium salts, the mash can be also acidified by means of biological acidification or the addition of mineral and organic acids, which apart from influencing the pH can alter the matrix in different ways. ...
... Increased aldehyde levels, the decrease in iso-α-acids responsible for the intensity and the quality of bitterness and the reduction in esters are the contemporary reported staling markers. [18][19][20][21] Bamforth [4] has pointed out that brewing textbooks predominantly rely on an empirical approach, with limited or absent references, when discussing "optimum" pH values for parameters like extract and wort filtration, repeatedly referencing previous textbooks rather than scientific studies. An important challenge often arises from the practice of measuring wort or mash pH at room temperature and assuming that these values remain constant at higher temperatures, which is not the case, as studies have shown that at 65 °C the pH of a wort can be approximately 0.35 pH units lower than its room temperature measurement. ...
... [6] Several components in wort, such as phosphates, free amino acids, peptides and polypeptides containing residues like aspartate and glutamate, contribute to its buffering capacity. [4,53] Factors elevating the levels of free amino acids, peptides and polypeptides (including the nitrogen content of the malt, Figure 6. effect of ph adjustment in the final wort on the electron spin resonance (eSr)-determined oxidative parameters. ...
... Unlike in western brewing, where calcium carbonate (to raise pH) or calcium sulfate/calcium chloride (to lower pH) are utilised, this is not practiced by local brewers during the mashing of sorghum grains, resulting in worts with a lower pH. Bamforth [162] reported the pH optima for malt enzymes and its impact in the mashing and mouth feel of the final beverage. The pH of wort and pito was documented as 3.62 ± 0.01 (0 h) and 3.43 ± 0.01 (72 h for single starter) and 3.50 ± 0.01 (72 h for mixed starter), at the start and end of fermentation [160]. ...
... The pH of wort and pito was documented as 3.62 ± 0.01 (0 h) and 3.43 ± 0.01 (72 h for single starter) and 3.50 ± 0.01 (72 h for mixed starter), at the start and end of fermentation [160]. A decrease in pH from 5.8 ± 0.1 to 4.6 ± 0.1 was observed by [162] before adding sea buckthorn into the green beer for further fermentation. As reported [162], the drop in pH is a result of the release of acids by the yeast coupled with the utilisation of buffering materials (free amino nitrogen) in the wort. ...
... A decrease in pH from 5.8 ± 0.1 to 4.6 ± 0.1 was observed by [162] before adding sea buckthorn into the green beer for further fermentation. As reported [162], the drop in pH is a result of the release of acids by the yeast coupled with the utilisation of buffering materials (free amino nitrogen) in the wort. The wort pH can influence yeast growth, flocculation, flavour production, etc. ...
Sorghum beer (pito) is an indigenous alcoholic beverage peculiar to northern Ghana and parts of other West African countries. It is overwhelmed with calories, essential amino acids (such as lysine, etc.), B-group vitamins, and minerals. In recent years, there has been a growing demand for highly flavoured yet functional pito in Ghana; however, the local producers lack the prerequisite scientific expertise in designing such products. We propose the utilization of Tetrapleura tetraptera (TT) and Hibiscus sabdariffa (HS) as cheap and readily available materials in designing functional flavoured pito. The addition of TT and HS would not alter the fermentation profile but rather augment the starter with nutrients, thus improving the fermentation performance and shelf life of the final pito. In vitro and in vivo studies provide substantive evidence of antioxidant, nephro-and hepato-protective, renal/diuretic effect, anticholesterol, antidiabetic, and antihypertensive effects among others of the TT and HS, hence enriching the pito with health-promoting factors and consequently boosting the health of the consumer. Herein, we summarise the phytochemical, biological, pharmacological, and toxicological aspects of TT and HS as well as the technology involved in brewing the novel bioactive-flavoured pito. In addition, we also report the incidence of heavy metal in conventional pito.
... This has been reported by Taylor (37) in 1990. In 2001, Bamforth (5) summarized data on the impact of pH during mashing on wort parameters. The highest extract yield was found in a pH range of 5.2-5.8, ...
... Too high buffering capacity of wort makes it difficult to end with an optimal beer pH between 4.2-4.5 after fermentation. Beer pH should be in this range in order to avoid problems with flavor stability, colloidal stability, foam stability, and the taste of the fresh beer (5). Phosphate content can be influenced by phytase activity during mashing. ...
... Significantly lower glucose concentrations were found in worts mashed with a pH of 5.2 (Fig. 10A). An optimum pH of 5.5 for mashing has been reported (5). A decrease to pH 5.2 clearly influences the α-amylase activity negatively. ...
The mashing process is of highest technological relevance for all following processes of wort and beer production. However, it is time consuming and therefore cost intensive. The influence of important mashing parameters on wort composition was investigated in order to shorten the mashing process by applying the thickest mashes without a negative influence on wort composition. The thickest mash leads to lower energy and water consumption in the brewhouse. On the other hand, the shortest mashing scheme results in the highest throughput. Finally, fine milling, mashing-in above gelatinization temperature, decreased mashing-in pH of 5.2, very thick mash of 1:2.3 malt:water ratio, and a holding time of 30-40 min at 64 degrees C followed by 15-20 min at 72 degrees C guarantees a high extract yield, normal attenuation limit, sufficient FAN level, required buffering capacity, and a reduced fatty acid oxidation. Lowering the pH to 5.2 at mashing-in results in lower glucose levels but the sum of fermentable sugar is not influenced due to a higher level of maltotriose and similar maltose levels. However, not all yeast strains assimilate maltotriose well in industrial fermentations. A mash pH of 5.2, positive for beer flavor stability, may result in a somewhat lower alcohol potential.
... The present Belgianstyle pale ale was characterized and compared to the Mexican guidelines (Table 4). The pH of beer (~4.5) [4] plays a crucial role in the colloidal stability of the product and its foam, as well as in the aroma, flavor, and sensation of the freshness of the beverage [20,55]. Additionally, its low pH serves to diminish the load of pathogens, coliform bacteria, and sporulated microorganisms [20]. ...
... A value under 4 may indicate the presence of bacteria and, at the same time, bring about a more bitter and metallic taste. At a pH above 4.5, beer can take on a soapy taste [55]. Another criterion for evaluating beer is total acidity as a measure of the content of organic acids, which confer sensory properties [56]. ...
There is an expanding market for beer of different flavors. This study aimed to prepare a craft Belgian-style pale ale with a non-Saccharomyces yeast. Pichia kudriavzevii 4A was used as a sole starter culture, and malted barley as the only substrate. The ingredients and brewing process were carefully monitored to ensure the quality and innocuousness of the beverage. During fermentation, the yeast consumed 89.7% of total sugars and produced 13.8% v/v of ethanol. The product was fermented and then aged for 8 days, adjusted to 5% v/v alcohol, and analyzed. There were no traces of mycotoxins, lead, arsenic, methanol, or microbiological contamination that would compromise consumer health. According to the physicochemical analysis, the final ethanol concentration (5.2% v/v) and other characteristics complied with national and international guidelines. The ethyl acetate and isoamyl alcohol present are known to confer sweet and fruity flavors. The sensory test defined the beverage as refreshing and as having an apple and pear flavor, a banana aroma, and a good level of bitterness. The judges preferred it over a commercial reference sample of Belgian-style pale ale made from S. cerevisiae. Hence, P. kudriavzevii 4A has the potential for use in the beer industry.
... The beer pH ranged from 4.01 to 4.49 which is within the expected pH range for lager beers [27]. The pH of beer is important when considering the sensory profile, it has been previously reported that low pH beers become more 'sharp' and have an increased sour taste [18,28]. The intensity of sour taste is related to the total concentration of free and undissociated hydrogen ions [18]. ...
... Adjuncts such as rice and maize contain low levels of nitrogenous compounds and phytase, the enzyme responsible for the breakdown of phytic acid to release phosphates. Therefore, adjuncts lessen the buffering capacity of wort and beer, leading to lower pH values [28]. Increasing nitrogenous compounds in the wort or reducing the amount of free hydrogen ions when brewing with adjunct material could potentially minimise this off flavour obtained in the 60% maize sample. ...
Brewing with unmalted cereal adjuncts can reduce the requirement for malting, thereby lowering costs and improving the overall sustainability of the brewing chain. However, substantial adjunct usage has technological challenges and the sensory characteristics of beers produced using high adjunct rates are still not fully understood. This study examined the impacts of brewing with unmalted barley, wheat, rice and maize at relatively high concentrations (0, 30% and 60% of grist) on the sensorial and analytical profiles of lager beer. Adjunct based beers and a 100% malt control were brewed at 25 L scale. A trained sensory panel (n = 8) developed a lexicon and determined the sensorial profile of beers. At 30% adjunct incorporation there was insignificant variation in the expected beer flavour profile. At 60% adjunct incorporation, there were some significant sensory differences between beers which were specific to particular adjunct materials. Furthermore, 60% adjunct inclusion (with correspondingly low wort FAN) impacted the fermentation volatile profile of the final beers which corresponded with findings observed in the sensory analysis. Developing an understanding of adjunct-induced flavour differences and determining strategies to minimise these differences will facilitate the implementation of cost-efficient and sustainable grist solutions.
... The buffering substances in brewing have been considered to be important for a long time (6). Therefore, a lot of research on pH, organic acids, and buffering capacity of wort was continually conducted over a long period of time (2)(3)(4)7,9,11,18,19). ...
... In the study of Coote and Kirsop, buffering capacity was measured as milliliters of 0.1N sulfuric acid required to change the pH of 1 L of wort from 5.0 to 4.0 (4). In a paper by Bamforth, the author simply mentioned that the buffering capacity of a wort can be assessed by adding acid to wort and assessing the extent to which measured pH changes (2). In a study by Torija et al., the buffering capacity of tartaric acid was tested by measuring the final fermentation pH (17). ...
The aim of this study was to develop a simple and practical method for evaluating the buffering capacity of wort. The pH values before and after addition of 0.4 mL of 1N HCl into 50 mL of wort were recorded, and the buffering capacity of wort was reported as the logarithm of the ratio of the addition of hydrogen ion to the increase in free hydrogen ion. The numerical value of buffering capacity determined by this developed method had a significant positive correlation with the content of buffering substances and was able to reflect the real ability of wort to resist the fall in pH during beer fermentation. The proposed method had good precision (below 0.5%). Generally, the proposed method is simple, rapid, and practical, and it can be used for routine analysis.
... Regarding pH, its value in beers usually ranges from 3.9 to 4.5, affecting their stability against microbial spoilage, colloidal, foam, and flavor stability, drinkability, and palate smoothness [38]. In the present work, the pH value was within this range in most cases, being slightly lower with the probiotic strain compared with the standard one (between 4.29-4.42 ...
The development of new non-dairy probiotic foods is interesting, given lactose intolerance, milk allergies, and the growing trend of vegetarianism. In this paper, beer has been used as a probiotic delivery matrix, using Saccharomyces boulardii as an alternative to conventional brewer’s yeast. The strain was able to grow in worts prepared with hops containing different alpha-acid concentrations, attaining in all cases a final cell concentration above 1·108 cells mL−1. Some differences were found in the physicochemical parameters of beers brewed with S. boulardii compared to those brewed with a standard brewer’s yeast. Probiotic beers turned out to be less cloudy, which could help with a possible filtering step; less alcoholic in some cases; a healthier alternative; and with a slightly lower pH, interesting for the reduction of spoilage risk. Thirty volatile compounds were determined in the samples, and, in general, the beers brewed with the probiotic yeast presented significantly higher concentrations for the majority of the studied volatile compounds. In addition, multivariate statistical analysis was successfully performed to differentiate the beers obtained in terms of their volatile composition. Probiotic and standard beers were also subjected to sensory analysis, and they presented similar results in their overall impression.
... Both the raw materials at the various stages of beer production and the final product should be tested for pH. Its value has a decisive influence on the taste, prevents the development of microorganisms and is a key factor influencing the maturation of beer, its stability and its durability [38,39]. ...
In this study, the process of the vacuum impregnation of Kangoo barley grain, at the stage of soaking, was used in the production of light malt. The influence of vacuum impregnation on the speed of the water uptake by the barley, at temperatures of 12, 14, 16 and 18 °C, was also analyzed. At this stage of the research, the grain was soaked in water to obtain a moisture content of approximately 42%. The samples for the moisture content tests were taken every 2 h. The grain intended for malt was soaked in an air–water system and was kept submerged in water for 6 h. It was then removed from the water and kept for 18 h. The grain was aerated during the soaking process. The malting and soaking lasted eight days at temperatures of 12, 14, 16 and 18 °C. The samples for further testing were taken daily. Then, each of the samples was dried, following the same procedure. The sprouts were removed immediately after the dried samples contained approximately 4% moisture. Following a 3-month maturation process, the congress wort was produced from the malt. The pH and the extract content in the wort were tested. It was found that the process of vacuum impregnation significantly accelerates the uptake of water by the grain. In almost all cases, the influence of the tested factors on the pH of the wort and the extract content was also observed.
... Regarding pH, growth for all strains were observed at pH 5 and 6 (Fig. 3B). However, unlike cheese strains, several beer-recovered strains showed resilience at pH 4 (i.e., C7, C11, C14, C17, C18, and C19), which may hint toward the adaptive behavior of LAB as beer is usually slightly acidic (Bamforth, 2001 , Fig. 3B). Growth of L. brevis and L. mesenteroides in beer at pH 3.75 and 4.0 has been reported, respectively (Rodríguez-Saavedra, González de Llano, & Moreno-Arribas, 2020). ...
The growth of lactic acid bacteria (LAB) in fermented foods, especially in ripened foods, could be associated with the production of biogenic amines (BAs). BAs are small, nitrogen-containing, thermostable, non-volatile organic compounds, which can induce toxic effects in food consumers. This work aimed to determine potential BAs-producer LAB strains isolated from ripened cheese and beer and to evaluate stress factors that induce the production of these metabolites. Determination of BAs-related genes in eighteen strains of LAB was done by polymerase chain reaction (PCR). The effect of pH, NaCl concentration and ethanol concentration on the LAB growth and BAs production was evaluated. The concentration of BAs (histamine, tyrosine, putrescine and cadaverine) was determined by high performance liquid chromatography (HPLC). Additionally, survival of selected LAB strains during beer making process was evaluated. All LAB strains could tolerate concentrations of 4 and 6 mL/100 mL of ethanol. More than one strain showed the ability to produce all the BAs studied and all beer strains were able to produce Tyramine. The pH level was the most influent factor in BAs production; pH 4 was optimal for the production of histamine (cheese and beer strains) and pH 5 for tyramine (beer strains). LAB population showed a 2-log reduction along the two initial days of fermentation. At the end of the beer making process 1.6 log of LAB were recovered. BAs production has been considered a mechanism that increases bacterial survival against acidic environment. Some LAB strains in fermented products may represent a health risk for consumers. Sanitary practices during food production and raw material quality should be complement measurements to a good control of fermentation process to minimize BAs presence in foods.
... Further preliminary trials conducted highlighted the need for a buffering mechanism. Whilst consistent results could be obtained using the malt base with the carbohydrates, and when using the yeast nitrogen base, the pH dropped from 5 to below 3 within the first 24 h, due to acidification resulting from the production of CO 2 [43]. This was accompanied by a slowing of the fermentation rate. ...
The utilisation of high gravity wort possessing a higher sugar content is frequently used to increase the capacity and efficiency of beer production. In such an environment, osmotic stress, lower nutrient availability, ethanol toxicity and elevated CO2 concentrations may decrease the sustainability of yeast performance and have a negative impact on the desired end product. Traditionally, apparent attenuation has been used as a standard measure of fermentability. Here, we describe a miniature fermentation assay with a defined fermentation media that could be used to assess fermentability on a small scale, including determination of the original gravity and final gravity of the medium for trials using four yeast strains. The results obtained using the defined media were approximately comparable to those obtained using regular wort in terms of their real attenuation limits and specific gravity, although the defined media demonstrated lower final pH values compared to the wort for several strains. With further optimisation, the mini fermentation process applied to a defined medium could provide the foundation for future analytical research into the brewing process, using techniques such as high-performance liquid chromatography (HPLC) and quantitative polymerase chain reaction (qPCR).
... From the quality perspective of beer, both the final product and raw materials from individual production stages are tested against pH value. This parameter has a crucial impact on the taste, prevents the growth of microorganisms and is a key factor for beer aging, its stability, and durability [8,9]. ...
Twenty-five elements, including the most essential and toxic metals, were determined in fifty beer samples stored in cans and bottles by Inductively Coupled Plasma Mass Spectrometry (ICP-MS), Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) and Cold Vapor Atomic Absorption Spectroscopy (CVAAS) techniques. The packaging material was analyzed using the Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS) technique. The control of the level of individual metals is necessary, not only to maintain the organoleptic properties of the product, but also to fulfill the standards regarding the permissible maximum concentrations. Metals can originate from different sources, including the brewing water, malt grains, hops, adjuncts, fruits, and spices. They may also come from contamination from the brewery equipment, i.e., vessels and tanks, including beer packing, storing and transporting (kegs, casks, cans). Discri-minant analysis revealed that the differentiation of three types of beer (Lager, Ale, Craft) was possible , based on elemental concentrations, for the reduced data set after their selection using the Kruskal-Wallis test. The analysis of the impact of the packaging material (can or bottle) proved that when this parameter was used as a differentiating criterion, the difference in the content of Na, Al, Cu and Mn can be indicated. The risk assessment analysis showed that the consumption of beer in a moderate quantity did not have any adverse effect in terms of the selected element concentrations, besides Al. However, in the case of Al, the risk related to consumption can be considered, but only for the beer stored in cans produced from aluminum.
... This higher extract does not always indicate higher fermentability. The mash pH for maximised fermentability is around 5.5-5.6 (37)(38)(39), since this is the pH optima at mashing temperatures (60-70°C) of αand β-amylase, measured in wort at room temperature. ...
Beer inevitably changes due to an array of staling reactions. A major factor in beer ageing is the involvement of transition metals (iron, copper, manganese) in oxidative reactions. To tackle the flavour stability issue, metal chelation was investigated. Based on previous research, five primary chelators (tannic acid, gallic acid, EDTA, citric acid and phytic acid) were screened using experimental design for their capacity to reduce the content of wort transition metals. The chelating agents were added under varying conditions (mash out temperature, mash pH, grain bill, chelator concentration, addition time) during laboratory scale mashing to assess how they altered complexation and metal load. Fourteen alternative chelators (ferulic acid, tartaric acid, quercetin, chlorogenic acid and ten polyphenolic food extracts: green tea, pomegranate, grape seed, reishi, cinnamon, curcuma, milk thistle, ginkgo, grapefruit seed and raspberry) were also explored. Metal ions were analysed using inductively coupled plasma optical emission spectrometry and wort oxidative stability by electron spin resonance spectroscopy. Mash pH was the most decisive of all tested process variables: acidified mashing (pH 6 to 5) produced worts with more iron, manganese and zinc (230, 320 and 150%, respectively). Addition of effective chelators counteracted this undesirable effect for iron. Green tea extract, tannic acid and, particularly, pomegranate extract all resulted in lower wort iron. Conversely, addition of EDTA, caused iron, manganese and zinc to increase. Pomegranate extract (90% ellagic acid) was the best performing chelator and reduced radical generation in wort (80% reduction by 60 mg/L addition), making it a promising novel compound in the improvement of beer shelf life. © 2021 The Authors. Journal of the Institute of Brewing published by John Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling.
... pH is an important factor in brewing quality beer. The pH levels during various stages of the brewing process affect extract potential, beer colour, hot-break formation, foam stability, hop oil extraction, hop bitterness and lauterability of the beer [27]. It is also an important consideration for beer quality during storage as a low pH inhibits bacterial growth. ...
Isomerized hop extract and methanolic extracts of Azadirachta indica, Garcinia kola, Gongronema latifolium and Vernonia amygdalina were profiled by the application of Gas Chromatography-Mass Spectrometry (GC-MS). The isomerized hop extract and ethanolic extracts of the plant species were used to brew beers. The aim was to study the GC-MS profiles of all the extracts comparatively and to investigate some physicochemical properties of beers brewed with hop extracts and in comparison, with beers brewed with extracts from the four Nigerian plants. The profiling of the metabolites in hop extracts and those of the Nigerian plants was carried out using Gas Chromatography-Mass Spectrometer. The physicochemical properties of the finished beer products were also carried out using standard methods. Beers brewed with extracts from the Nigerian plants were statistically ranked by the application of Analysis of Variance (ANOVA) to ascertain their potentiality. The GCMS results showed that these plants contained metabolites comparable to those of hops, although some metabolites [dehydro-cohumulunic acid; 4,4-dimethyl-2-buten-4-olide; 1,2-dimethyl-cyclopropane carboxylic acid; lupulone; 2,5-dimethyl-2-hexanol; 4,4,5,5-tetramethyl-bicyclo hexyl-6-ene-2,3-dione; octadecanoic acid, oxiranyl methyl ester and 1,2-benzenedicarboxylic, bis(-2-ethyl hexyl) ester] present in hops were absent in the Nigerian plants. Isomerized hop, hop leaf, G. kola and V. amygdalina extracts contained 14, 11, 12 and 9 metabolites respectively while those of A. indca and G. latifolium contained 10 metabolites each. The physicochemical properties of the brewed beers revealed that the alcohol content in all the beer samples ranged from 3.43-3.75%, total acidity (0.132-0.324%), pH (5.47-5.68), turbidity (5-125NTU), total solids (3.66-8.16%) and bitterness level (25.38-39.62IBU). The concentration of arsenic in the beer samples ranged from 1.44-1.77ppm, cadmium (0.00-0.97ppm) and copper (0.10-2.70ppm). Test of significant (p-value) in all the tested plants was greater than 0.05 at 95% confidence interval. Consequently, the extracts from tested Nigerian plants could be used as suitable substitutes for hops in beer brewing without alteration of physicochemical properties of beer, G. kola having the greatest potential as substitute for hops.
... Second, organic acids can protect beer from microbiological attack by decreasing pH (6,23). Third, organic acids in beer can contribute to prolonged shelf life, because they supply a strong buffering capability (1,13,23,25). Organic acids are one of the most important components contributing to beer buffering capability, which is correlated with beer turbidity, foam stability, and the rate of flavor staling (25). ...
J. Am. Soc. Brew. Chem. 65(2):86-91, 2007 The concentration of six organic acids (acetic acid, lactic acid, pyruvic acid, malic acid, citric acid, and succinic acid) and pH were determined in 45 beer samples (23 from China and 22 from other countries) with the intention of associating the "moderate to very sour" character of Chinese local beers with particular acids. The content of acetic, lactic, and total organic acids in Chinese lagers was significantly higher, while citric acid was much lower, than that of foreign brands (P < 0.05). Using discriminant analysis, both stepwise and with all variables included, moderately strong classifications were obtained using the magnitude of the original gravity (low, medium, and high), the origin of the beer (Chinese or foreign), and the sourness intensity (slightly, moderately, and very sour) as the classification categories. These analyses supplied more information about organic acids in beer and its associated effect on the properties of lager beer. RESUMEN La concentración de seis ácidos orgánicos (ácido acético, ácido láctico, ácido pirúvico, ácido málico, ácido cítrico, y ácido succínico) y el pH fue-ron determinados en 45 muestras de cerveza (23 de China y 22 de otros países) con la intención de asociarse el carácter "moderado a muy agrio" de cervezas locales de china con ácidos particulares. El contenido de áci-do acético, ácido láctico, y ácido orgánicos total en cervezas de tipo lager de China era perceptiblemente más alto, mientras que el ácido cítrico era mu-cho más bajo que el de marcas de fábrica extranjeras (P < 0.05). Usando análisis discriminante, escalonado y con todas las variables incluidas, cla-sificaciones fuertes fueron obtenidas usando la magnitud de la gravedad original (punto bajo, medio, y alto), el origen de la cerveza (China o ex-tranjera), y la intensidad de la acidez (levemente, moderado, y muy agrio) como las categorías de la clasificación. Estos análisis proveyeron más in-formación sobre los ácidos orgánicos en cerveza y su efecto asociado so-bre las características de la cerveza de tipo lager.
... pH is an important factor in brewing quality beer. The pH levels during various stages of the brewing process affect extract potential, beer colour, hot-break formation, foam stability, hop oil extraction, hop bitterness and lauterability of the beer [40]. It is also an important consideration for beer quality during storage as a low pH inhibits bacterial growth. ...
Aim: The aim is to investigate some physicochemical properties of beers and polycyclic aromatic hydrocarbons contaminants in beer brewed with isomerized hop extract and in comparison with beers brewed with extracts from four Nigerian potential hop substitutes. Study Design: Beers were brewed using isomerized hop extract and extracts from four Nigerian bitter vegetables. Analyses of physicochemical properties of the beers and for the presence of 16 specific target PAHs were carried out using their respective standard methods. Place and Duration of Study: Analysis of physicochemical properties of the beers was done at Nigerian Breweries PLC, Enugu while analysis for PAHs was conducted at Central Laboratory, Nigerian Institute for Oceanography and Marine Research, Lagos between July, 2018 and November, 2019. Methodology: Physicochemical properties of the beers (alcohol content, bitterness level, pH, specific gravity, colour) were determined using their respective standard methods. Gas chromatography/mass spectrometry was used in analyzing for PAHs [naphthalene, acenaphthylene, acenaphthene, phenanthrene, anthracene, fluoranthene, pyrene, benzo(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, dibenzo(a,h)anthracene, indeno(1,2,3-cd)pyrene and benzo(g,h,i)perylene]. Four isotopically labelled PAHs (acenaphthene-d10, phenanthrene-d10, chrysene-d12 and perylene-d12) were used as internal standards. Results: Alcohol content (%v//v) in the beer samples is A(5.20); B(4.28); C(4.40); D(4.43) and E(4.54), bitterness level in International Bitterness Units (IBU) is A(0.54); B(0.80); C(1.46); D(1.46) and E(0.08), pH is A(4.36); B(3.08); C(3.88); D(3.90) and E(3.87), specific gravity is A(10.06); B(10.00); C(10.00); D(10.06) and E(10.06), and beer colour is A(5.80); B(7.70); C(6.60); D(8.00) and E(7.40). All 16 EPA PAHs were not found in all the beer samples except pyrene which was detected in sample B at a concentration of 0.00402 mg/kg. Conclusion: It is concluded that extracts from the four Nigerian bitter vegetables could be used as substitutes for isomerized hop extract and that consumption of beer produced using extract from G. kola poses great public health concerns.
... Novel prediction parameters of malt extract and beer filterability were also observed between malt extract and pH (r = À0.424-0.630). Bamforth (53) noted that pH has important implications for enzyme efficiency during malting and mashing, with a lower pH improving extract and the solubilisation of free amino acids (54,55). ...
Colourimetric assays were used to measure the activities of six key hydrolases endogenous to barley: β‐glucanase, xylanase, cellulase, α‐amylase, beta‐amylase and limit dextrinase. The analysed barley malt samples were previously characterised by 27 conventional malt quality descriptors. Correlations between enzymatic activities and brewing parameters such as extract yield, fermentability, viscosity and filterability were investigated. A single extraction protocol for all six hydrolases was optimised and used for multi‐enzyme analysis using fully automatable assay formats. A regression analysis between malt parameters was undertaken to produce a relationship matrix linking enzyme activities and conventional malt quality descriptors. This regression analysis was used to inform a multi‐linear regression approach to create predictive models for extract yield, apparent attenuation limit, viscosity and filterability using the Small‐scale Wort rapId Filtration Test (SWIFT) and two different mashing protocols – Congress and a modified infusion mash at 65°C (MIM 65°C). It was observed that malt enzyme activities displayed significant correlations with the analysed brewing parameters. Both starch hydrolases and cell wall hydrolase activities together with modification parameters (i.e. Kolbach index) were found to be highly correlated with extract yield and apparent attenuation limit. Interestingly, it was observed that xylanase activity in malts was an important predictor for wort viscosity and filterability. It is envisaged that the automatable measurement of enzyme activity could find use in plant breeding progeny selection and for routine assessment of the functional brewing performance of malt batches. This analytical approach would also contribute to brewing process consistency, product quality and reduced processing times. © 2019 The Institute of Brewing & Distilling
... TA increased from 0.83 ± 0.01 to 1.88 ± 0.02% for wort and beverage. Substance in wort and beer can affect their buffering abilities, notable the residue of proteins like aspartate and glutamate (Bamforth, 2001). According to , utilisation of substrate in wort and accumulation of metabolites is responsible for fluctuations in TA. ...
Triticale is hybrid crop developed by crossing wheat (Triticum) and rye (Secale) and in last years it become more popular for food applications, including flake production. Different approaches are developed to improve flakes technology by applying different cooking, rolling, toasting parameters resulting in high quality products. All these technologies influence also nutrition quality of product due to the different stability of these compounds during mechanical and thermal treatment. The aim of current experiment was to investigate the influence of technological parameters on chemical composition of triticale flakes. In current experiment triticale grains and triticale flakes obtained by different technologies was tested. For evaluation of the influence of technological parameters, different flaking and rolling parameters were tested. For all samples were determined composition of basic nutrients (fats, proteins, fibres, sugars, ash), minerals (Ca, Mg, K, Zn, P), vitamins, total phenolics and antioxidant activity. Triticale has high nutritional quality, containing significant amounts of protein, fibres, vitamins and minerals. Technological processes significantly influence cereals composition, but it depends on parameters tested. Control sample showed lower results and hierarchical cluster analyses showed that samples 1/3/1, 2/1/2/1, 2/1/3/1, 2/1/4/1 are similar in composition of bioactive compounds. Results showed that for selection of the best method for flaking physical and/or sensory properties should be taken in account.
... The pH of two experimental beers was 4.71 for M. gelida and 4.60 for S. ludwigii. Generally, above pH 4.0 the beers take on toasted characters and even soapy and caustic notes (Bamforth, 2001;Guyot-Declerck et al., 2005). However, the two obtained beers, despite the pH values exceeding 4.4, did not show the negative notes above mentioned, as demonstrated by the sensory analysis. ...
Due to the increasing consumer demand, the production of low alcoholic and non alcoholic beer is the new goal of the present brewing producers. Although the beer with reduced alcohol content is currently obtained by physical methods, the use of non-Saccharomyces yeast, with low fermentations capacities, may represent an interesting biological approach. In this study the ethanol content and the volatile profile of a beer obtained using the basidiomycetous psychrophilic yeast strain Mrakia gelida DBVPG 5952 was compared with that produced by a commercial starter for low alcohol beers, Saccharomycodes ludwigii WSL17. The two beers were characterized by a low alcohol content (1.40% and 1.32% v/v) and by a low diacetyl production (5.04 and 5.20 μg/L). However, the organoleptic characteristics of the beer obtained using M. gelida are more appreciated by the panelists, in comparison to the analogous produced with the commercial strain of S. ludwigii.
... Pri kvasení pH klesá veľmi rýchlo vplyvom vznikajúceho CO 2 . Už druhý deň po zakvasení klesne hodnota pH na hodnotu okolo 4,4 a tá sa už v ďalšom procese mení len nepatrne [20]. ...
The effects of the properties of hopped worts on the course of fermentationand beer character were monitored in this work. Hoppedwort pH in the range of 5,1-5,4 has insignificant effects on the speedof primary fermentation, the breakdown of diacetyl was faster in caseof hopped worts with pH = 5,1 (6,9 days), the slowest diacetyl breakdownwas observed for hopped worts with pH = 5,4 (11,4 days). Fromorganoleptic point of view, finished beers prepared from hopped wortswith a higher pH were preferred.With different wort aeration (8 mg/l, 9 mg/l and 10 mg/l of oxygen),no differences were observed during fermentation. The day of yeastremoval from cylindro-conical fermenters, decrease in diacetyl contentas well as the number of dead yeast cells (to 2 %) were comparable.In case of hopped worts with a higher trub content, 1 day longerbreakdown of vicinal diketones (diacetyl) to the value required,lower foam stability (by 5 s - 2 %) and a lower colloidal stability(approx. by 3 weeks - 9 %) were observed, but no differences inthe organoleptic properties of fresh beers. In case of infusion mashing,a higher haze level at the angle of 90° and a lower haze levelat the angle of 15° were observed in unhopped wort. In hoppedwort, a higher haze level in case of infusion mashing as wellas during decoction mashing at the angle of 90° and 15° was observed.The effects of the properties of hopped worts on the course of fermentationand beer character were monitored in this work. Hoppedwort pH in the range of 5,1-5,4 has insignificant effects on the speedof primary fermentation, the breakdown of diacetyl was faster in caseof hopped worts with pH = 5,1 (6,9 days), the slowest diacetyl breakdownwas observed for hopped worts with pH = 5,4 (11,4 days). Fromorganoleptic point of view, finished beers prepared from hopped wortswith a higher pH were preferred.With different wort aeration (8 mg/l, 9 mg/l and 10 mg/l of oxygen),no differences were observed during fermentation. The day of yeastremoval from cylindro-conical fermenters, decrease in diacetyl contentas well as the number of dead yeast cells (to 2 %) were comparable.In case of hopped worts with a higher trub content, 1 day longerbreakdown of vicinal diketones (diacetyl) to the value required,lower foam stability (by 5 s - 2 %) and a lower colloidal stability(approx. by 3 weeks - 9 %) were observed, but no differences inthe organoleptic properties of fresh beers. In case of infusion mashing,a higher haze level at the angle of 90° and a lower haze levelat the angle of 15° were observed in unhopped wort. In hoppedwort, a higher haze level in case of infusion mashing as wellas during decoction mashing at the angle of 90° and 15° was observed.
... During the storage of lager beer, its pH value typically decreases in the 4.5-3.9 range, leading to inferior flavor stability (Bamforth 2001). Grigsby et al. showed that lowering the pH and subsequent forced-aging (1 d, 60 C) results in the deterioration of flavor stability. ...
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.
... TA increased from 0.83 0.01 to 1.88 0.02% for wort and beverage. Substance in wort and beer can affect their buffering abilities, notable the residue of proteins like aspartate and glutamate (Bamforth, 2001). According to Adadi et al. (2017b), utilisation of substrate in wort and accumulation of metabolites is responsible for fluctuations in TA. ...
Antioxidant evokes numerous health benefits to the consumer as well as stabilisation of the beverages flavours. Therefore, this paper provides detailed information on the application of Monascus purpureus IHEM LY2014-0696 in combination with various malts in brewing antioxidant rich beverage (ARB). Starter culture Angkak was prepared by solid state bioprocessing (SSB). Single infusion method of mashing was used. Physicochemical parameters, volatile compounds, DPPH (2, 2-diphenyl-1-picrylhydrazyl) radical scavenging activity and fermentability of the wort were evaluated. Distillation procedure based on pycnometry technique was use to quantify the alcohol content (%ABV). Fermentability of the wort was found to be 97.6 ± 0.46% whilst %ABV was equal to 5.42 ± 0.03. It was observed that ARB showed a strong DPPH radical scavenging activity of 1.00 × 10-4 mol × equ (R 2 = 0.91) whereas 3.43 × 10-5 mol × equ (R 2 = 0.81) for wort. The strong antioxidant activity (AOA) is thought to be caused by pigments produced by M. purpureus IHEM LY2014-0696 and other compounds originated from the malts and hops utilised in brewing ARB. A total of 4 volatile compounds were identified in the present study. Incidence of microbial load ranged from 2.14 ± 0.04 × 10 7 and 0.8 ± 0.1 × 10 5 for M. purpureus IHEM LY2014-0696 and bacterial respectively was observed in the ARB. This study contradicts some previous ones, as the ARB brewed did not take the red pigment produced by the M. purpureus. Panellists generally expressed their acceptance for the ARB as they assessed it as a new product, moreover, taking account its health benefits.
... Second, acids can help protect beer from harmful microorganisms by decreasing the pH [36]. Third, the organic acids present in beer can aid in prolonging the shelf life by providing the beer with a strong buffering capability [36,38]. Acetic acid has a flavor threshold of 200 ppm, while lactic acid has a flavor threshold of 400 ppm [26,39]. ...
Lambic beer is the oldest style of beer still being produced in the Western world using spontaneous fermentation. Gueuze is a style of lambic beer prepared by mixing young (one year) and older (two to three years) beers. Little is known about the volatiles and semi-volatiles found in commercial samples of gueuze lambic beers. SPME was used to extract the volatiles from nine different brands of lambic beer. GC-MS was used for the separation and identification of the compounds extracted with SPME. The pH and color were measured using standard procedures. A total of 50 compounds were identified in the nine brands. Seventeen of the 50 compounds identified have been previously identified. The compounds identified included a number of different chemical groups such as acids, alcohols, phenols, ketones, aldehydes, and esters. Ethyl acetate, 4-ethylphenol, and 4-ethylguaiacol are known by-products of the yeast, Brettanomyces, which is normally a spoilage microorganism in beer and wine, but important for the flavor characteristics of lambic beer. There were no differences in pH, but there were differences in color between the beer samples.
... A decrease in pH from 5.8 ± 0.1 to 4.6 ± 01 at the 4 th week was observed in Fig. 2. Additionally, there was no further diminishing in pH the after the 4 th week when SBT was added in the green beer. pH falls amid ageing accordingly due to utilisation of buffering materials (free amino nitrogen) by yeast and the release of natural acids (Bamforth, 2001). We realized that malt worts are the phenomenal wellspring of nitrogen, minerals, and vitamins. ...
In recent years, there has been a growing demand for non-traditional beer (craft) with different flavours hence the main aim of this research is to produce beer with sea buckthorns (SBT). Brewing software BeerSmith was used to design the Kölch beer. After one month of primary fermentation, SBT were sanitised and crashed before adding into the green beer. Carbonation was done using keg with 1.8 bar of carbon dioxide. Physicochemical properties, microbial load and sensory evaluation of Kölch fruit beer (KFB) were determined. All the physiochemical parameters measured were significantly (P < 0.05) influenced by the fermentation time. The pH dropped from 5.8 ± 0.1 to 3.9 ± 0.1 toward the end of the fermentation. There was no microbial growth when KFB was inoculated in the media. °Brix likewise decreases from 13.3 ± 0.43 to 3.86 ± 0.25. There was a change in the colour of the wort throughout the fermentation from 11.2 ± 0.44 to 32.5 ± 0.56 EBC. A decrease from 1.48 ± 0.02 to 0.86 ± 0.02 mg maltose per 100 mL in the reducing sugar was observed during the entire period of fermentation. A total of 32 volatile compounds were identified. All assessed sensory variables of KFB were significantly different (P < 0.05) and preferred by the panellists, however, foaminess and clarity of KFB should have to be improved. KFB showed higher DPPH radical scavenging activity as compared to other types of beer examined due to biologically active substances contributed by SBT.
... In wort, nitrogenous com-pounds are regarded as major contributors to the BC (16,17). Factors promoting the level of these compounds, such as the nitrogen content of the malt and the extent of proteolysis occurring in mashing, will elevate the BC (18). ...
Acidified wort produced biologically using lactic acid bacteria (LAB) has application during sour beer production and in breweries adhering to the German purity law (Reinheitsgebot). LAB cultures, however, suffer from end product inhibition and low pH, leading to inefficient lactic acid (LA) yields. Three brewing-relevant LAB (Pediococcus acidilactici AB39, Lactobacillus amylovorus FST2.11 and Lactobacillus plantarum FST1.7) were examined during batch fermentation of wort possessing increasing buffering capacities (BC). Bacterial growth was progressively impaired when exposed to higher LA concentrations, ceasing in the pH range of 2.9–3.4. The proteolytic rest (50°C) during mashing was found to be a major factor improving the BC of wort. Both a longer mashing profile and the addition of an external protease increased the BC (1.21 and 1.24, respectively) compared with a control wort (1.18), and a positive, linear correlation (R2 = 0.957) between free amino nitrogen and BC was established. Higher levels of BC led to significant greater LA concentration (up to +24%) after 48 h of fermentation, reaching a maximal value of 11.3 g/L. Even higher LA (maximum 12.8 g/L) could be obtained when external buffers were added to wort, while depletion of micronutrient(s) (monosaccharides, amino acids and/or other unidentified compounds) was suggested as the cause of LAB growth cessation. Overall, a significant improvement in LA production during batch fermentation of wort is possible when BC is improved through mashing and/or inclusion of additives (protease and/or external buffers), with further potential for optimization when strain-dependent nutritional requirements, e.g. sugar and amino acids, are considered. Copyright © 2017 The Institute of Brewing & Distilling
... As is typical during ethanol fermentation, the pH of our batch system decreased, likely because the uptake of buffering materials such as amino nitrogen compounds, the excretion of organic acids [22], the utilization of ammonium-which releases hydrogen ions outside of the cell [23]-and the production of carbonic acid due to the reaction of carbon dioxide (released by yeast) with water. Nevertheless, given the data on glucose consumption and ethanol production in batch fermentation (Fig. 1), the medium system was adequately buffered and was able to achieve relatively high fermentation efficiency and biomass yield. ...
Background
The cellulosic ethanol industry has developed efficient strategies for converting sugars obtained from various cellulosic feedstocks to bioethanol. However, any further major improvements in ethanol productivity will require development of novel and innovative fermentation strategies that enhance incumbent technologies in a cost-effective manner. The present study investigates the feasibility of applying self-cycling fermentation (SCF) to cellulosic ethanol production to elevate productivity. SCF is a semi-continuous cycling process that employs the following strategy: once the onset of stationary phase is detected, half of the broth volume is automatically harvested and replaced with fresh medium to initiate the next cycle. SCF has been shown to increase product yield and/or productivity in many types of microbial cultivation. To test whether this cycling process could increase productivity during ethanol fermentations, we mimicked the process by manually cycling the fermentation for five cycles in shake flasks, and then compared the results to batch operation.
Results
Mimicking SCF for five cycles resulted in regular patterns with regards to glucose consumption, ethanol titer, pH, and biomass production. Compared to batch fermentation, our cycling strategy displayed improved ethanol volumetric productivity (the titer of ethanol produced in a given cycle per corresponding cycle time) and specific productivity (the amount of ethanol produced per cellular biomass) by 43.1 ± 11.6 and 42.7 ± 9.8%, respectively. Five successive cycles contributed to an improvement of overall productivity (the aggregate amount of ethanol produced at the end of a given cycle per total processing time) and the estimated annual ethanol productivity (the amount of ethanol produced per year) by 64.4 ± 3.3 and 33.1 ± 7.2%, respectively.
Conclusions
This study provides proof of concept that applying SCF to ethanol production could significantly increase productivities, which will help strengthen the cellulosic ethanol industry.
... For instance, citric and malic acids have two types of fresh acid fla-vors, while succinic acid has an unpleasant salty, bitter flavor, as well as being sour. Organic acids in beer also contribute to changes in pH, acidity, and buffering capability, all of which have a great impact on beer flavor and nonbiological stability (1,23). Organic acids also influence susceptibility to spoilage organisms, protecting the beer from microbiological attack to some extent (7,22). ...
Organic acids in malt play an important role in determining the pH and buffering capability of wort. The organic acids content of commercial malts and factors influencing this content were investigated with the intention of better controlling organic acids in the required range. The content and proportion of each organic acid in different commercial malts varied greatly. Analysis of the correlation between organic acids and corresponding malt specifications indicated that malic acid in malts had a high positive correlation with Kolbach index (0.961), and pyruvic acid showed good negative correlation (-0.869) with acetic acid in malts. The difference in patterns of change for seven organic acids (pyruvic, malic, lactic, acetic, citric, fumaric, and succinic) during steeping, germinating, and kilning are also described in detail. One-at-a-time experiments confirmed that barley variety, malting conditions, and microorganisms were mainly responsible for the great variety in organic acids content in final malts, which may be very useful information for helping brewers to improve malt quality and satisfy brewery requirements.
... pH is the measure of the concentration of hydrogen ions, [H + ], in solution, and it indicates the negative log10 of [H + ], first introduced by the Danish scientist S. P. L. Sorensen in 1909 (2,15). pH not only has a major effect on beer production but also influences beer quality. ...
The buffering capacity of wort plays an important role in determining the pH of beer. The technological factors influencing buffering capacity of wort were investigated as the first steps toward the eventual goal of better controlling beer pH to a target range. The technological factors studied included the proportion of adjuncts, multistep infusion mashes, the dosage of calcium salt, and the type of acidifying reagent. Analysis of the regression between buffering capacity of wort and the proportion of rice adjuncts indicated that buffering capacity of wort linearly fell with the increase in the percentage of rice adjuncts, and the rice adjuncts contributed approximately half as much buffering substances as malt. The wort from multistep infusion mashes had a relatively high buffering capacity. Acid rest and protein rest were able to elevate the buffering capacity of wort. The buffering capacity tended to drop with the increase in the amount of addition of calcium salt. Phosphoric acid, lactic acid, and acetic acid can be used for acidifying mash to target pH. The buffering capacity of the wort with acetic acid as the acidifying reagent was the highest, and the buffering capacity of the wort with phosphoric acid as the acidifying reagent was the lowest. Organic acids such as lactic acid and acetic acid had stronger buffering capacity than phosphoric acid at the pH of wort.
Why was the work done: With respect to terroir, ‘To be or not to be,’ (Hamlet, Shakespeare) is a key question for maltsters and brewers for malt and beer quality. Terroir is a sparsely studied aspect of malt quality, despite it being an important component of added market-value in wine since ancient times. The ‘sense of place’ imbued by terroir is an expression of the growth of a grape variety in a specific region with respect to local climate, soil, microbiome, elevation/aspect of the vineyard, viticultural and wine making methods. Similar corollaries to wine terroir can be drawn for hops and malting barley. How was the work done: A comprehensive review of the literature was undertaken to identify reports of terroir in barley/malt quality. Where possible, the discussion was extended by consideration of appropriate unpublished data. What are the main findings: The primary influence of terroir on malt is grain protein content (GPC). This appears, in part, to be controlled by the daylength during grain maturation. Increasing day length typical of grain maturation in Australia tends to be associated with a lower GPC, while decreasing daylength during grain maturation in Canada is associated with a higher protein content. GPC is positively correlated with diastatic power, beta-amylase activity and foam positive proteins such as protein Z4 and hordeins. Conversely, GPC is inversely correlated with extract and Kolbach Index (KI). Interestingly, lower protein barley tends to produce higher KI malts that result in wort with greater flavour complexity and desirability. The level of ionic micronutrients (cations, anions) including calcium and zinc are understudied aspects of malt quality. It is evident that there is significant variation in the ionic micronutrient content of malt produced from different international regions and between regions of the same country which would be an expression of terroir. Lastly, the microbiome of barley/malt shows influences of terroir such as the deleterious impacts of Fusarium head blight on malt quality including gushing and mycotoxins. Variation in terroir will also have more subtle impacts, both desirable and undesirable, on malt quality for the contribution of beneficial enzymes (e.g., cell wall degrading enzymes) or for the propensity of barley to impart malt components into wort (e.g., arabinoxylan) that have been implicated in premature yeast flocculation (PYF) and undesirable beer quality. Why is the work important: The concept of terroir in malt quality has important implications for the efficiency of mashing, lautering, fermentation and beer quality.
There is an increase in the popularity of craft beer, which is produced by small, independent, and traditional breweries. Since craft beer popularity is rising in Portugal this research focused on assessing physicochemical parameters, total phenolic content (TPC) and the antioxidant capacity of Portuguese craft beers and raw materials used in beer production. In this experimental study, 19 beer samples were analyzed. Parameters such as pH, Total Acidity, Reducing Sugar Content and TPC were evaluated. For the determination of antioxidant activity, DPPH scavenging activity and metal chelating activity (MCA) were analyzed in all samples. Craft beers demonstrated a high phenolic content (ranging from 343.78 mg GAE/L to 2172.49 mg GAE/L), significantly different from industrial beers. Craft beers demonstrated a higher inhibition of DPPH radicals and higher MCA than the raw materials. DPPH inhibition ranged from 36.5% to 96.0% for malt and 64.7% to 79.6% in hops samples. MCA also varied between the different samples, with results of 12.0% to 24.8% in malt samples and 3.8% to 23.5% in hops. Raw materials can potentially influence the antioxidant activity of the resulting beer. Positive correlations between TPC and physicochemical properties can be useful to help consumers choose beers with added value for health.
The paper discusses the influence of the oak chips addition on physicochemical properties of beer. The research material consisted of wort and beer after the fermentation, brewed in the English porter style. Medium toasted oak chips, from two varieties of an oak tree (French and American), were used. Variants without the addition of oak chips were used as control samples. The research was conducted for three periods: after 18 days, 2, and 3 months. The samples containing oak chips were characterized by higher fermentation efficiency, compared to beers without the addition of chips. Titratable acidity increased with aging time in beers containing the chips. Alcohol content decreased after 3 months in all samples. Increased amounts of oak chips and aging time, resulted in greater free amino nitrogen utilization. Prolonging the storage time of the beer with the addition of oak chips changed the profile of volatile components in the beverages.
Non-conventional yeasts can be isolated from a wide range of environmental sources and are often found in the beverage industry in mixed fermentations, in which the microbial community is usually not fully known. However, it is important to know the compositions of these starter cultures because in addition to enabling reproducibility during fermentation, other properties can be discovered. Thus, the objective of this work was to identify and characterize non-conventional yeasts isolated from the environment, evaluating their probiotic potential and possible use in beer brewing. Isolates were obtained from flowers, fruits, leaves and mixed-fermentation beers, with the species being identified by PCR. Yeasts with promising activity were evaluated regarding their growth under different pHs, temperature and the presence of organic acids. To explore probiotic potential, in vitro tests were performed for antimicrobial activity and co-aggregation with food-spoiling microorganisms, auto-aggregation and survival in simulated gastrointestinal tract conditions. In this study, Pichia kluyveri (LAR001), Hanseniaspora uvarum (PIT001) and Candida intermedia (ORQ001) were selected among 20 isolates for further study. P. kluyveri was the only strain that tolerated pH 2.5. Lactic acid was not inhibitory, but acetic acid and incubation at 37 °C had partially inhibitory effects on yeast growth. All yeasts tolerated α-acids from hops and up to 1% NaCl. Our results also suggest that these isolates are able to adhere to intestinal cells and positively influence the host to combat pathogens, as they showed auto-aggregation rates > 99% and antagonistic activity to pathogenic bacteria. The yeasts tolerated gastric environment conditions, but were more sensitive to pancreatic conditions. We conclude that these non-conventional yeasts have probiotic potential and promising application in beer fermentation.
Buffering capacity (BC) is one of the important quality parameters of wort. In this study, the effect of single amino acids on brewing wort pH and its influence in wort BC were investigated. A beer sweet wort (BSW) was used as a control. A synthetic sweet wort (SSW) and synthetic sweet wort without amino acids (SSWNA) were prepared for a general comparison due to its absence of peptides. BC was conducted by the addition of hydrochloric acid. Results showed that a BSW and a SSW differed in their BC because SSW did not contain small peptides/peptides/polypeptides; SSWNA lost its BC severely due to its absence of nitrogenous compounds. Among all amino acids, arginine, and glutamic acid presented a higher influence in initial pH. However, aspartic acid wort demonstrated the best BC; therefore, this amino acid can be used to control the BC of brewers wort.
The filtration and pasteurization steps at beer production have vital importance for consumer expectations and a long shelf‐life. Also, phenolics have a significant role in the organoleptic characteristics and antioxidant activity of beers. This study mainly aimed to determine the exact effects of every filtration step and pasteurization processes on different alcohol concentrated beers from the same malts at the parameters such as total antioxidant activity (TAA), total phenolic content (TPC), and phenolic distribution. Principal component analyses (PCA) and fully linked clusters were carried out to evaluate the relationship between the parameters. According to the results, it was determined that the filtration caused the decrease of around 12% of TPC and 7% of TAA, while the pasteurization process did not affect the examined parameters at each alcoholic concentration. During the research, (+)‐catechin and protocatechuic acid were the most affected phenolics, while gallic acid and quercetin hydrate were the least.
Gluten-free beer could be produced with rice, although the latter would primarily serve as adjunct in combination with barley malt in today’s brewing. But, the recent growing realisation on the potentials and applications of rice malt for brewing an all-rice malt beer through varying malting conditions cannot be overlooked. In this study, therefore, the characteristic changes in malt, wort, and beer from different Nigerian rice varieties (FARO 44, FARO 57, NERICA 7) as influenced by varying malting conditions (steeping duration (18, 24 and 30 h), germination periods (2, 3 and 4 days) and kilning temperatures (50 and 55 �C)), were investigated. Rice (grain) samples were examined by thousand kernel weight (TKW), germinative energy (GE), germinative capacity (GC), and degree of steeping (DoS). To ensure that rice wort/beer with unique beer style and enhanced attributes, comparable to barley wort/beer is produced, malting conditions that produced rice malts with peak diastatic power (DP), cold water extract (CWE), and hot water extract (HWE) were selected. Peak DP, CWE and HWE were obtained at FARO 44 (18 h steeping, 3 days germination, 55 �C kilning (S18G3K55�)), FARO 57 (30 h steeping, 2 days germination, 50 �C kilning (S30G2K50�)) and NERICA 7 (24 h steeping, 3 days germination, 55 �C kilning (S24G3K55�)). Selected malts were further tested for moisture content, total nitrogen, malt yield and malting loss and subsequently progressed to wort and beer production. Wort’s pH, total soluble nitrogen (TSN), brix, kolbach index (KI), free amino nitrogen (FAN), dextrose equivalent (DE), original extract (OE) and sugar profile were determined, as well as beer’s pH, colour, apparent extract (AE), alcohol by volume (%ABV), turbidity and sensory attributes. Rice grain varied significantly (p < 0.05) in TKW, GE, GC and DoS across varieties. Despite wort’s pH, TSN, DE, OE as well as beer pH, colour, AE and turbidity resembling (p > 0.05) across varieties, wort’s brix, KI, FAN, sugar profile as well as beer’s %ABV, differed significantly (p < 0.05). Sensory attributes of appearance, colour, mouthfeel, and overall acceptability in beer differed noticeably (p < 0.05),except for aroma and taste (p > 0.05). Overall, the rice beer, though very slightly hazy, represented a pale yellow light lager, which is indicative of its peculiar beer style. Besides increased DP and enhanced hydrolysis, varying malting conditions of current study could serve as a pathway of reducing the cost of exogenous (commercial) enzymes or barley malt imports, together with decreasing barley’s dependency for
brewing in the tropics.
A key first step in the production of beer is the mashing process, which enables the solubilization and subsequent enzymatic conversion of starch to fermentable sugars. Mashing performance depends primarily on temperature, but also on a variety of other process parameters, including pH and mash thickness (known as the “liquor-to-grist” ratio). This process has been studied for well over 100 years, and yet essentially all predictive modeling efforts are alike in that only the impact of temperature is considered, while the impacts of all other process parameters are largely ignored. A set of statistical and mathematical methods collectively known as Response Surface Methodology (RSM) is commonly applied to develop predictive models of complex processes such as mashing, where performance depends on multiple parameters. For this study, RSM was used to design and test a set of experimental mash conditions to quantify the impact of four process parameters—temperature (isothermal), pH, aeration, and the liquor-to-grist ratio—on extract yield (total and fermentable) and extract composition in order to create a robust, yet simple, predictive model. In contrast to previous models of starch hydrolysis in a mash, a unique aspect of the model developed here was the quantification of significant parameter interaction effects, the most notable of which was the interaction between temperature and mash thickness (i.e., the liquor-to-grist ratio). This interaction had a sizeable impact on important mash performance metrics, such as the total extract yield and the fermentability of the resultant wort. The development of this model is of great future utility to brewery processing, as it permits the multi-parameter optimization of the mashing process.
The paper reviews a career of more than forty years researching topics in malting and brewing science. Some themes attracted particularly close attention, namely the endosperm cell walls of barley, dimethyl sulphide, flavour stability, foam and the impact of beer on health. However, the scope has been far broader than that. The underlying imperative was to pursue research that was close to application and always focussed on a specific need in the processes involved in the production of beer. © 2020 The Institute of Brewing & Distilling
Lactic acid bacteria (LAB) fermentation performance is essential for aroma metabolites formation and product flavour quality. Hence, this study appraises high‐gravity malt wort fermentation (HGF) by three LAB strains to improve the fermentation performance and consumer's acceptance of lactic acid‐fermented malt‐based beverages (LAFMB). HGF at 20% (w/w) provided higher amino acid content and buffering capacity that allowed greater cell development, viable cell count and sugar utilisation. Moreover, the pH change was lesser although marked lactic acid accumulation. It is noteworthy that HGF significantly incremented the content of higher alcohols (+0 – 161%), 2‐phenylethanol (+11–147%), acetaldehyde (+27–44%) and β‐damascenone (+25 – 66%) comparing to low‐gravity malt wort at 12%. Thus, HG‐fermented beverages were significantly preferred with greater hedonic scores (4.6 ± 2.1). Our results indicate that HGF is a valuable strategy for improving LAB fermentation performance in malt wort, which in turn increases key aroma compound content resulting in enhanced acceptance of LAFMB.
Binary brush structures consisting of poly(cysteine methacrylate) (PCysMA) “corrals” enclosed within poly(oligoethylene glycol methyl ether methacrylate) (POEGMA) “walls” are fabricated simply and efficiently using a two-step photochemical process. First, the C-Cl bonds of 4-(chloromethyl)phenylsilane monolayers are selectively converted into carboxylic acid groups by patterned exposure to UV light through a mask and POEGMA is grown from unmodified chlorinated regions by surface-initiated atom-transfer radical polymerization (ATRP). Incorporation of a ratiometric fluorescent pH indicator, Nile Blue 2-(methacryloyloxy)ethyl carbamate (NBC), into the polymer brushes facilitates assessment of local changes in pH using a confocal laser scanning microscope with spectral resolution capability. Moreover, the dye label acts as a radical spin trap, enabling removal of halogen end-groups from the brushes via in situ dye addition during the polymerisation process. Second, an initiator is attached to the carboxylic acid-functionalised regions formed by UV photolysis in the patterning step, enabling growth of PCysMA brushes by ATRP. Transfer of the system to THF, a poor solvent for PCysMA, causes collapse of the PCysMA brushes. At the interface between the collapsed brush and solvent, selective derivatisation of amine groups is achieved by reaction with excess glutaraldehyde, facilitating attachment of aminobutyl(nitrile triacetic acid) (NTA). The PCysMA brush collapse is reversed on transfer to water, leaving it fully expanded but only functionalized at the brush-water interface. Following complexation of NTA with Ni2+, attachment of histidine-tagged proteorhodopsin and lipid deposition, light-activated transport of protons into the brush structure is demonstrated by measuring the ratiometric response of NBC in the POEGMA walls.
This study was conducted to compare the effect of different acidification methods using Lactobacillus amylovorus FST2.11 as a starter culture on the microbiological, technological, and qualitative attributes of sour beers. Biological souring was performed in the mash after mashing, in the preboiling wort, or in the postboiling wort. This lactic acid bacterium strain was selected for its high sensitivity to hops, good growth at moderate levels of alcohol, and fast acidification in wort. Alcoholic fermentation was carried out using a commercial Saccharomyces cerevisiae (Safale US-05) strain. Desired acidification of the unhopped substrates (approximately 5-6 g/L of lactic acid) was achieved within 18 h of lactic fermentation. The lactic culture consumed maltose preferentially over monosaccharides, and uptake of free amino nitrogen was limited (8.0- 12.6 mg/L). Yeast growth in soured substrates was delayed by 2-4 days compared with the unacidified control, but comparable end attenuations were achieved among all treatments. Among the soured beers, the lowest levels of off-flavors were found in preboil wort souring trials, whereas cofermented beers led to opalescent beers containing high levels of total diacetyl and acetoin. The low pH and the high level of staling compounds such as acetaldehyde suggest that sour beers suffered from low oxidative stability. Final beer qualities varied considerably depending on the souring method applied. Souring of wort by L. amylovorus FST2.11 before boiling was found to produce bright, tart beer with minor organoleptic failures while limiting the risk of bacterial cross-contamination within the brewing facility. The renewed interest that sour brewing has received among brewing communities worldwide calls for a better understanding of the advantages and disadvantages of different souring methods. The results from this study could help brewers to choose the most suitable approach according to equipment capabilities and sensorial likeness.
1 BIOGRAPHICAL REVIEW 3 Enzymes, Egg White and Eccentrics 4 Memories from 37 years of research in the brewing industry 6 Charles W. Bamforth, 1 Department of Food Science and Technology, University of California, Davis, CA 8 1 Corresponding author. E-mail: cwbamforth@ucdavis.edu; phone: +1-530-752-9476; fax: +1-530-752-
The effect of the buffering capacity of wort on a beer fermentation and the contribution of pH, phosphate, amino acids and organic acids to the buffering capacity of wort were studied. The beer pH depended on the buffering capacity of the corresponding wort and an increase in the buffering capacity of the wort could prolong the time of diacetyl conversion. The higher the wort pH was, the larger the wort buffering capacity. Phosphate was not an effective buffer at the pH of wort. Glutamic acid, aspartic acid and histidine gave weak contributions to the buffering capacity of wort, and the total contribution of these three amino acids was <0.1. Organic acids contributed substantially to the buffering capacity of the wort and the total contribution of organic acids to the buffering capacity of the wort was estimated to be about 0.31. The buffering capacity of lactic acid, citric acid, succinic acid, fumaric acid and pyruvic acid was 30, 50, 77, 15 and 9% of that of acetic acid, respectively, at the same mass concentration. Copyright © 2015 The Institute of Brewing & Distilling
This paper reports on the application of the rapid visco-analyzer (RVA) to further understand Theological changes that are taking place during the brewery mashing process. Clear correlations were found between the level of amylase present in mashes and the rheological data points representing primary grain/starch swelling and subsequent starch digestibility. In addition, secondary starch gelatinization Theological data representing consistency-viscosity increases because of the presence of smaller starch granules were clearly correlated with the level of mash amylase. The influence of mash pH on starch gelatinization/liquefaction and amylase activities could be quantified from the Theological data. Clear correlations were found between the added levels of β-glucanase on a β-glucan substrate and the recorded Theological trends. Overall, the studies clearly show the interactions between grain components (purified/nonpurified), amylolytic enzymes, glucanolytic enzymes, and mash pH and how they individually and collectively influence the consistency-viscosity profiles during the mashing process. In addition, the results further validate the RVA as being a suitable instrument for determining mash Theological changes. Application of the methods can provide the maltster, brewer, or distiller with more functional information regarding raw materials and process conditions.
Beer contains numerous taste and aroma compounds. Some of them are derived from the raw materials malt and hops but by far the most are formed during the brewing process, which consists of several steps. Fermentation is of particular importance. Depending on the yeast strain and the conditions more or fewer flavour compounds are formed. Hops contribute significantly to beer bitterness and beer flavour. Evidence is presented that the isometric beer bitter acids have different bitter intensities. After bottling, the beer flavour is unstable and changes considerably with time. The use of a marker compound to measure staling in research and development studies of beer flavour stability is described.
The instruction of prospective brewers in the matter of beer and brewing is far more than a means for teaching chemistry in the context of what is for many a desirable and pleasurable product. A good appreciation of the essential principles of chemistry and biochemistry is certainly an a priori requirement to fully understand the processes of converting crops into the world's favorite adult beverage. However it is equally important for a student to have a decent grasp of plant physiology, chemical engineering, microbiology, physics, sensory science and more besides. They need to be energized with a passion for the process and the product. The most valuable brewing courses in academia are taught by (or at the very least coordinated by) individuals with a genuine understanding of the realities of life within the industry.
Measurement of the pH of small-scale barley mashes prepared with ale, Munich, and pilsner malt mashed with artificially alkalized and calcium-hardened water revealed that the classic Kolbach residual alkalinity equation needs to be modified to be applicable to mashing conditions. Parameters for equations following the residual alkalinity pattern were determined. Adjustment parameters for each type of malt are reported. In addition, a titration curve for pilsner malt was determined. The results can be useful in predicting mash pH from water and malt parameters.
Addition of stabilisation products in the upstream brewing process is a very convenient way of physico-chemical stabilisation without the need for extra fi ltration or the risk of beer losses. Therefore, in this study the use of appropriate stabilisation products upstream the brewing process, more specifi cally at the end of wort boiling, have been evaluated in relation to improved colloidal stability. Applications of PVPP (Polyclar 10, ISP) and gallotannins (Beerotan Q, BFTI) have been investigated. The lowest gallotannin levels (wort boiling: 5 g/hL; contact time in boiling kettle: 3 minutes) are already sufficient to obtain enhanced stability due to adequate removal of haze- sensitive proteins. Furthermore, the addition of 10 g/hL PVPP has an explicit effect on the amounts of polyphenols, which results in an improved colloidal stability. Lowering pH at mashing-in also results in improved physico-chemical properties and flavour stability.
The brewing industry is facing an ever increasing challenge to become more cost-effective, while at the same time maintaining or improving product quality. Brewing with unmalted oats (Avena sativa L.) has the potential to reduce the costs of raw materials. However, the replacement of malted barley with unmalted oats can also adversely affect the quality and processability of mashes, worts, and beers. In this study, brewing with unmalted oats (040%) and malted barley was carried out in a 60-L pilot plant. The impact of various levels of oats on mashing, lautering, and fermentation performance was monitored in detail and the quality of the final beers was evaluated using Lab-on-a-Chip capillary electrophoresis as well as standard methods specified by Mitteleuropäische Brautechnische Analysenkommission (MEBAK), European Brewery Convention (EBC), or the American Society of Brewing Chemists (ASBC). It has been found that the beta-glucan content and viscosity of mashes and worts increased significantly with increasing amounts of oats. In addition, the use of 20% or more oat adjunct resulted in a clearly increased lautering time. The replacement of barley malt with unmalted oats also had adverse effects on total soluble nitrogen (TSN), free amino nitrogen (FAN), and extract levels in worts. The foam stability of the final beers decreased significantly using 20% oats or more. However, their sensory quality improved with increasing levels of oat adjunct. Keywords: Beer quality, Brewing, Mashing, Oat adjunct, Wort processability
Background: One of the challenges facing the fuel ethanol industry is the management of bacterial contamination during fermentation. Lactobacillus species are the predominant contaminants that decrease the profitability of biofuel production by reducing ethanol yields and causing "stuck" fermentations, which incur additional economic losses via expensive antibiotic treatments and disinfection costs. The current use of antibiotic treatments has led to the emergence of drug-resistant bacterial strains, and antibiotic residues in distillers dried grains with solubles (DDGS) are a concern for the feed and food industries. This underscores the need for new, non-antibiotic, eco-friendly mitigation strategies for bacterial contamination. The specific objectives of this work were to (1) express genes encoding bacteriophage lytic enzymes (endolysins) in Saccharomyces cerevisiae, (2) assess the lytic activity of the yeast-expressed enzymes against different species of Lactobacillus that commonly contaminate fuel ethanol fermentations, and (3) test the ability of yeast expressing lytic enzymes to reduce Lactobacillus fermentum during fermentation. Implementing antibiotic-free strategies to reduce fermentation contaminants will enable more cost-effective fuel ethanol production and will impact both producers and consumers in the farm-to-fork continuum. Results: Two genes encoding the lytic enzymes LysA and LysA2 were individually expressed in S. cerevisiae on multi-copy plasmids under the control of a galactose-inducible promoter. The enzymes purified from yeast were lytic against Lactobacillus isolates collected from fermentors at a commercial dry grind ethanol facility including Lactobacillus fermentum, Lactobacillus brevis, and Lactobacillus mucosae. Reductions of L. fermentum in experimentally infected fermentations with yeast expressing LysA or LysA2 ranged from 0.5 log10 colony-forming units per mL (CFU/mL) to 1.8 log10 (CFU/mL) over 72 h and fermentations treated with transformed yeast lysate showed reductions that ranged from 0.9 log10 (CFU/mL) to 3.3 log10 (CFU/mL). Likewise, lactic acid and acetic acid levels were reduced in all experimentally infected fermentations containing transformed yeast (harboring endolysin expressing plasmids) relative to the corresponding fermentations with untransformed yeast. Conclusions: This study demonstrates the feasibility of using yeast expressing bacteriophage endolysins to reduce L. fermentum contamination during fuel ethanol fermentations.
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