Mashing Procedure Research Articles

Mashing Isothermally at High Temperature Compared to Infusion Mashing for the Production of Full-Bodied, Alcohol-Reduced Beer

The objective of this study was to investigate the influence of the mashing temperatures on alcohol content and taste of bottom-fermented Pilsner style beers and to ascertain whether these beers exhibit comparable sensorial properties. For this purpose, three beers brewed with three different mashing procedures were compared. The worts produced were sampled during mashing and after boiling, and subsequently analysed for their original gravity, fermentable sugars, and free amino nitrogen. The beers were analysed for their alcohol content, aroma compounds, apparent degree of fermentation, pH value, foam, and bitterness units as well as being evaluated sensorially according to DLG (= “Deutsche Landwirtschafts-Gesellschaft - German Agricultural Society”) grading in the categories: odour, purity of taste, body, carbonation, quality of bitterness. Overall it was shown, that the isothermal mashing procedure yielded less fermentable but more unfermentable sugars than the two more traditional mashing procedures, leading to a comparable original wort of 11.6°P in the final beer and lower alcohol content of 2.8% v/v in comparison to the more traditional mashing procedures (“high-short” and “simplified high-short” mashing procedure) with original worts of 12.1°P and alcohol contents of 4.5% v/v and 5.0% v/v, respectively. The DLG-rating showed that the beers derived from the different mashing procedures were all classified similarly with scores above 4.5 on average (out of 5.0) in all categories with no significant differences.

Assessment of green lentil malt as a substrate for gluten-free beer brewing

The aim of this study was to analyze whether it is possible to brew beer without using cereals so that the produced beverage could be easily accessible for the population suffering from celiac disease and other gluten-related disorders. Green lentil seeds were malted and then mashed using a congress mashing procedure to assess their advantages and disadvantages in the brewing process. Based on the congress mashing procedure, the mashing process needed to produce beer was developed, and beers were produced from the lentil malts germinated during malting for 96 h, 120 h and 144 h. It was possible to produce beers from the lentil malts; however, they were characterized by a lower alcohol content, lower degree of attenuation and some discrepancies between the concentrations of various volatiles (such as acetaldehyde, ethyl acetate, and 1-propanol) compared to the control beer produced from barley malt.

Production of gluten-free beer brewing from sorghum malts mashed without external enzyme preparations

One of the main substrates for beer production is barley malt. Due to that fact, consumption of the most popular alcoholic beverage in the world is limited for the population suffering from celiac disease and other disorders. However, there are various cereals and pseudocereals which are gluten-free and could possibly be utilised for the malt and beer production. In this study, we have determined that it is possible to produce gluten-free beer from two sorghum varieties (GK Emese and Anggy) without the use of external amylolytic enzymes, only by application of malting and decoction mashing procedures. Sorghum beers were characterised with lower alcohol and higher extract content than control barley malt beer sample. Concentration of various volatiles, such as so-called fusel alcohols, was also lower in the sorghum beers produced in this study.

Modification mechanism of protein in rice adjuncts upon extrusion and its effects on nitrogen conversion during mashing

The traditional production of wort with adjunct-introduced was achieved by double mashing procedure, which hindered the utilization of proteins in adjunct and led to a deficiency of nitrogen in wort. In this study, the modification mechanism of the extrusion pretreatment on the structure characterization of rice flour protein was investigated. The decoction mashing procedure was performed to enhance the nitrogen conversion of the extruded rice adjunct. Decreased solubility along with disrupted secondary and tertiary structures of rice protein were observed after extrusion. As a result, the total nitrogen, free amino nitrogen, and free amino acids content of wort with extruded rice adjunct-introduced were improved by 23.28 %, 34.67 %, and 7.33 %, respectively, which could be verified by the electrophoretic patterns of the wort protein. The application of extrusion as a pretreatment of adjuncts can promote the protein availability of adjuncts in the decoction mashing stage.

Impact of mashing protocol on the formation of fermentable sugars from millet in gluten-free brewing

The production of fermentable sugars (FS) in gluten-free (GF) brewing is hindered by the high starch gelatinization temperatures of GF malts and lower diastatic power compared to barley malt. Our previous work has demonstrated that starch gelatinization was the primary hurdle, and when decoupled from a single mash phase, high concentrations of FS could be produced. However, more research was required to improve the applicability of GF brewing. In this study, millet was used as a model GF malt demonstrating that despite the low α-amylase and β-amylase activities compared to barley malt ∼ 90 % of the FS (∼110 g/L) could be produced within 40 min. Limitations to enzyme extraction and separation due to coarse milling and lautering initially limited FS by ∼ 30 g/L, requiring additional processing or exogenous enzyme supplements that improved fermentable sugar generation by ∼ 20 g/L. Overall, millet is a promising brewing ingredient, provided appropriate mashing procedures are implemented.

Constant temperature mashing at 72 °C for the production of beers with a reduced alcohol content in micro brewing systems

In this paper, we present a constant temperature mashing procedure where grist made of Pilsner malt is mashed-in directly in the temperature regime of alpha-amylase activity, thus omitting all conventional steps, followed by constant temperature mashing at 72 °C. The aim was to investigate an alternative mashing procedure for the production of alcohol-reduced beers. The mashing proceeds with a rapid buildup of sugars and is completed after 120 min at the latest, giving an iodine normal and clear wort. However, the distribution of the different sugars in the worts is strongly altered, in comparison to a more classical mashing procedure. The free amino nitrogen (FAN) concentration is sufficient for vivid fermentation with the bottom fermenting yeast Saccharomyces pastorianus TUM 34/70. The lag phase and initial fermentation performance of this yeast strain are comparable for conventionally and isothermally (72 °C) mashed wort. Under the given conditions the fermentation of the isothermally (72 °C) made wort is finished after 6 days whereas a conventional wort needs 4–5 days more to be completed. The alcohol concentration is remarkably reduced by isothermal mashing leading to roughly 3.4 vol.-% with an original gravity of 11°P whereas with a conventional mashing procedure 4.4 vol.-% are obtained for the same original gravity. In both cases the concentrations of the fermentation by-products are comparable. A preliminary comparison of taste and foam stability did not show striking differences. Constant temperature mashing at 72 °C is a simple way to reduce the alcohol content of beer enriching it at the same time with non-fermentable sugars.

Gelatinization or Pasting? The Impact of Different Temperature Levels on the Saccharification Efficiency of Barley Malt Starch.

Efficient enzymatic hydrolysis of cereal starches requires a proper hydrothermal pre-treatment. For malted barley, however, the exact initial temperature is presently unknown. Therefore, samples were micro-mashed according to accurately determined gelatinization and pasting temperatures. The impact on starch morphology, mash viscometry and sugar yields was recorded in the presence and absence of an amylase inhibitor to differentiate between morphological and enzymatic effects. Mashing at gelatinization onset temperatures (54.5–57.1 °C) led to negligible morphological and viscometric changes, whereas mashing at pasting onset temperatures (57.5–59.8 °C) induced significant starch granule swelling and degradation resulting in increased sugar yields (61.7% of upper reference limit). Complete hydrolysis of A-type and partial hydrolysis of B-type granules was achieved within only 10 min of mashing at higher temperatures (61.4–64.5 °C), resulting in a sugar yield of 97.5% as compared to the reference laboratory method mashing procedure (65 °C for 60 min). The results indicate that the beginning of starch pasting was correctly identified and point out the potential of an adapted process temperature control.

A Modified Brewing Procedure Informed by the Enzymatic Profiles of Gluten-Free Malts Significantly Improves Fermentable Sugar Generation in Gluten-Free Brewing

The mashing step underpins the brewing process, during which the endogenous amylolytic enzymes in the malt, chiefly β-amylase, α-amylase, and limit dextrinase, act concurrently to rapidly hydrolyze malt starch to fermentable sugars. With barley malts, the mashing step is relatively straightforward, due in part to malted barley’s high enzyme activity, enzyme thermostabilities, and gelatinization properties. However, barley beers also contain gluten and individuals with celiac disease or other gluten intolerances should avoid consuming these beers. Producing gluten-free beer from gluten-free malts is difficult, generally because gluten-free malts have lower enzyme activities. Strategies to produce gluten-free beers commonly rely on exogenous enzymes to perform the hydrolysis. In this study, it was determined that the pH optima of the enzymes from gluten-free malts correspond to regions already typically targeted for barley mashes, but that a lower mashing temperature was required as the enzymes exhibited low thermostability at common mashing temperatures. The ExGM decoction mashing procedure was developed to retain enzyme activity, but ensure starch gelatinization, and demonstrates a modified brewing procedure using gluten-free malts, or a combination of malts with sub-optimal enzyme profiles, that produces high fermentable sugar concentrations. This study demonstrates that gluten-free malts can produce high fermentable sugar concentrations without requiring enzyme supplementation.

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

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. 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. 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. 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. 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.

Soaking in Aqueous Ammonia (SAA) Pretreatment of Whole Corn Kernels for Cellulosic Ethanol Production from the Fiber Fractions

Corn fiber is a co-product of commercial ethanol dry-grind plants, which is processed into distillers dried grains with solubles (DDGS) and used as animal feed, yet it holds high potential to be used as feedstock for additional ethanol production. Due to the tight structural make-up of corn fiber, a pretreatment step is necessary to make the cellulose and hemicellulose polymers in the solid fibrous matrix more accessible to the hydrolytic enzymes. A pretreatment process was developed in which whole corn kernels were soaked in aqueous solutions of 2.5, 5.0, 7.5, and 10.0 wt% ammonia at 105 °C for 24 h. The pretreated corn then was subjected to a conventional mashing procedure and subsequent ethanol fermentation using a commercial strain of natural Saccharomyces cerevisiae with addition of a commercial cellulase. Pretreatment of the corn with 7.5 wt% ammonia solution plus cellulase addition gave the highest ethanol production, which improved the yield in fermentation using 25 wt% solid from 334 g ethanol/kg corn obtained in the control (no pretreatment and no cellulase addition) to 379 g ethanol/kg corn (a 14% increase). The process developed can potentially be implemented in existing dry-grind ethanol facilities as a “bolt-on” process for additional ethanol production from corn fiber, and this additional ethanol can then qualify as “cellulosic ethanol” by the Environmental Protection Agency’s (EPA’s) Renewable Fuels Standard and thereby receive RINs (Renewable Identification Numbers).

Analytical Characterization of the Hydrolysis of Barley Malt Macromolecules During Enzymatic Degradation Over Time Using AF4/MALS/RI.

The changes on the molecular weight distribution (MWD) and particle size distribution (PSD) during hydrolysis of barley malt in isothermal mashing procedures were determined using asymmetrical flow field flow fractionation coupled to multiangle laser light scattering and refractive index (AF4/MALS/RI). Mash/trials were focused on amylolytic starch degradation. Therefore, temperatures (65, 70, and 75 °C) were selected according to α- and β-amylases range of activity. Samples were produced by triplicate, tracking amylolytic processes over time periods from 10 to 90 min in each mash/trial. AF4/MALS/RI analysis demonstrated significant differences on the values of the MWD and PSD according to the temperature/time profile used. At mashing times over 30 min at a temperature of 65 °C, when α- and β-amylase are both active, the decrease over time of the MWD and PSD was significantly higher (P < 0.005) than at 70 °C when mainly α-amylase is active. At 75 °C, also the activity of α-amylase decreased and the MWD and PSD were significantly lower (P < 0.005) than at 70 or 65 °C at any time of the procedure. The MWD and PSD of beer components influence beer palate fullness, thus AF4/ MALS/RI would be a powerful tool for breweries to adapt their technological processes to obtain beers with particular sensorial attributes.

Malting Sorghum with Aspergillus Oryzae Enhances Gluten-Free Wort Yield and Extract

Production of gluten-free beers is growing in the international market as an alternative for celiacs. In this investigation, white sorghum was malted conventionally and after inoculation of soaked kernels with 1 or 2% (w/w) koji (Aspergillus oryzae) for four days. The resulting sorghum diastatic malts were compared with barley malt and characterized in terms of α-amylase, β-amylase, and amyloglucosidase activities and employed to produce sweet worts following the double mashing procedure. Yields or wort extracts, fermentable carbohydrates, and free amino nitrogen (FAN) characterizations were assessed. The addition of 1% (w/w) A. oryzae to sorghum kernels before malting did not affect germination capacity (97.3%), whereas inoculation with 2% (w/w) resulted in about 5% less germination. At the end of the five-day malting procedure, the malts had similar dry matter losses. The α-amylase activity of malts was positively affected by the addition of A. oryzae, whereas the β-amylase was unaffected. Amyloglucosidase activity of malts was positively or negatively affected, respectively, by the addition of 1 or 2% koji. Worts produced from the sorghum malt inoculated with 1% koji generated 27% more fermentable carbohydrates and 24% more FAN after the double mashing procedure. More importantly, 1% koji inoculation malt only generated 8.8% less fermentable sugars compared with the barley malt. The major difference between the barley wort and the different sorghum worts was in maltose concentration, which clearly favored the barley wort. The sorghum malt inoculated with 2% koji did not further increase yield of fermentable sugars. This research clearly indicates that the inoculation of 1% koji during the malting of sorghum is advantageous in terms of diastatic activity and generation of fermentable carbohydrate in worts produced following the double mashing procedure. The regular sorghum and the sorghum malt + 1% koji produced 12°P worts with 40 and 21% less fermentable sugars compared with the barley control wort. Therefore, the supplementation of the sorghum malt with koji has potential to increase extracts and fermentable sugars in gluten-free worts.

Technological and Engineering Trends for Production of Gluten-Free Beers

Beer is the main alcoholic beverage consumed worldwide. It is essentially composed of malt, adjuncts or grist, hops, water and metabolites produced by yeast. Produced regularly with barley, it is unsuitable for patients with celiac disease due to the presence of storage proteins known as hordeins. A recent boom in the production of gluten-free beers has been attributed to the awareness of celiac disease and the significant boost in the gluten-free market size. Several strategies have been recognized as suitable gluten-free brewing procedures: by using non-gluten grains, non-grain sources such as sugars, syrups and honey and enzymatic and microbial treatments of barley worts to reduce to non-significant levels (<20 ppm/L), the peptides or epitopes which trigger celiac disease. Since the traditional brewing process uses barley, the use of other grains, such as rice, maize, sorghum, buckwheat or different types of millets, involves differences in both malting and mashing procedures especially in terms of process times and temperatures. Sorghum has been especially recognized for its potential to substitute barley since it is widely used in many countries of Africa to create traditional opaque beers, but compared to barley malt lacks of sufficient diastatic power due to the lower synthesis of both α- and β-amylases, and additionally, the starch requires higher temperatures for gelatinization. Likewise, rice, maize, millets and buckwheat are being used as source of both malt and grist with similar problems as sorghum. Potential future approaches involve the genetic engineering of barley in order to remove the peptides of the storage proteins that cause the allergic reaction on celiac patients and the employment of recombinant yeasts or other fermenting microorganisms that express prolyl endoproteinases which hydrolyze celiac immunoreactive epitopes into non-harmful peptides.

Evaluation of the potentials of millet, sorghum and barley with similar nitrogen contents malted at their optimum germination temperatures for use in brewing

Studies on the malting physiology of barley have led to similar studies on millet and sorghum. This study compares the outcomes of the malting physiology of millet, sorghum and barley. Results show that optimal development of diastatic power, soluble nitrogen, hot water extract and the wide range of amino acids of these three cereals is related to optimal malting conditions and appropriate mashing procedures. Transfer of the nitrogen/extract/soluble nitrogen/diastatic concepts of barley malt do not apply to millet and sorghum. However, all the cereals studied produced the range of amino acids required by yeast for fermentation. Sorghum malt released the highest amounts of group 1 amino acids, usually taken up faster by yeast. It also produced and released the highest amounts of amino acids, classified as group 2, which are assimilated more slowly than group 1 amino acids. It also produced and released more of the amino acids that are slowest to be assimilated during fermentation, as well as very high levels of proline. Optic barley malt produced and released the least amount of proline. The fate of proline during yeast fermentation is not clear, but it is believed that proline is not utilized during fermentation. Copyright © 2013 The Institute of Brewing & Distilling

Determination of the influence of starch sources and mashing procedures on the range of the molecular weight distribution of beer using field-flow fractionation

To produce experimental beers, different mash mixtures (barley malt, barley malt + 30% pre-cooked maize, barley malt + 30% nonmalted spelt) and distinct mashing procedures (infusion and decoction) with variations of the rest time and initial temperatures were evaluated. The range of molecular weight distribution (MWD) of the resulting beers was determined using asymmetrical flow field flow fractionation coupled to multiangle laser light scattering and refractive index. There were no differences on the range of MWD among the beers, according to infusion or decoction, using similar raw materials and initial temperatures (45 and 55°C). However the range of MWD was higher (p < 0.005) when using infusion at an initial temperature of 63°C, regardless of the raw material. The use of maize did not alter structural properties of the beer, while mash containing nonmalting spelt caused an elevation on the MWD (p < 0.001) and a lower (p < 0.05) apparent degree of fermentation. Therefore the range of the MWD of the beers was influenced by the quality of the raw material and the initial mashing temperature, whereas apparent degree of fermentation values were affected only by the type of starch source. Thus the determination of the MWD is an important tool for monitoring the production of beer. Copyright © 2013 The Institute of Brewing & Distilling

Effect of teff (Eragrostis tef) variety and storage on malt quality attributes

Varieties of a cereal may have a considerable influence on malting qualities owing to variations in the physicochemical properties of the grains. This research was aimed at assessing the influence of five teff varieties on malt quality attributes. The teff samples were malted using previously optimized malting conditions and mashed with the congress mashing procedure. In this research, the Kuncho teff variety was malted in a one year period after harvesting, whereas the other four varieties were malted after three years of storage. Alpha- and β-amylase, and limit dextrinase activity, were in the ranges 14–68, 10–440 and 375–1072 U/kg, respectively. Extracts ranged from 54% for Dessie to 74% for Ivory teff. Free amino nitrogen, protein content, soluble nitrogen, Kolbach index, viscosity and wort colour were in the ranges 160–364 mg/L, 8.6–13.6%, 532–1048 mg/100 g, 24–50%, 1.441–1.629 mPa s and 5.9–9.0 EBC units, respectively. High-performance liquid chromatographic analysis for individual fermentable sugars revealed that the highest value in all varieties was recorded for glucose followed by maltose. The concentration of glucose ranged from 9.49 g/L in Brown teff, to 19.42 g/L in Ivory teff, whereas maltose ranged from 2.95 g/L in Dessie teff to 16.1 g/L in Kuncho teff. All of the malt quality attributes considered in this study were markedly influenced (p < 0.05) by the type of teff cultivar. It was concluded that the use of different teff varieties yielded malts with significantly different malt quality attributes. Copyright © 2013 The Institute of Brewing & Distilling

Malting Extremely Small Quantities of Barley

Micromalting procedures for malt quality analysis typically use 150–500 g of barley and can produce malt with characteristics representative of malts produced on a commercial scale. Modifications to routine micromalting protocols, in which small quantities of grain contained within inexpensive mesh containers are surrounded by a larger quantity of grain in standard malting containers, allow representative malts to be generated from 2 g of barley. This reduced scale enables multiplexing of samples within a malting container, thereby increasing the potential malting throughput of existing micromalting equipment. The combination of this extremely small-scale malting procedure with previously described reduced-quantity mashing and malt analysis procedures effectively expands the capacity for preliminary screening of malt quality characteristics, benefiting malting barley germplasm development programs by both increasing malting quality analysis sample throughput and reducing analysis turnaround time. In addition, the ability to generate and analyze representative malts on this very small scale would be useful in research studies where grain quantities are limited, such as might occur in specially developed genetic populations for basic research studies on the genetic and biochemical underpinnings of malting quality.

Optimisation of the Mashing Procedure for 100% Malted Proso Millet (Panicum miliaceum L.) as a Raw Material for Gluten-free Beverages and Beers

Proso millet is a gluten-free cereal and is therefore considered a suitable raw material for the manufacturing of foods and beverages for people suffering from celiac disease. The objective of this study was to develop an optimal mashing procedure for 100% proso millet malt with a specific emphasis on high amylolytic activity. Therefore, the influence of temperature and pH on the amylolytic enzyme activity during mashing was investigated. Size exclusion chromatography was used to extract different amylolytic enzyme fractions from proso millet malt. These enzymes were added into a pH-adjusted, cold water extract of proso millet malt and an isothermal mashing procedure was applied. The temperatures and pH optima for amylolytic enzyme activities were determined. The α-amylase enzyme showed highest activity at a temperature of 60°C and at pH 5.0, whereas the β-amylase activity was optimum at 40°C and pH 5.3. The limit dextrinase enzyme reached maximum activity at 50°C and pH 5.3. In the subsequent mashing regimen, the mash was separated and 40% was held for 10 min at 68°C to achieve gelatinisation. The next step in the mashing procedure was the mixture of the part mashes. The combined mash was then subjected to an infusion mashing regimen, taking the temperature optima of the various amylolytic enzymes into account. It was possible to obtain full saccharification of the wort with this mashing regimen. The analytical data obtained with the optimised proso millet mash were comparable to barley wort, which served as a control.

Small-scale mashing procedure for predicting ethanol yield of sorghum grain

A small-scale mashing (SSM) procedure requiring only 300 mg of samples was investigated as a possible method of predicting ethanol yield of sorghum grain. The initial SSM procedure, which was conducted similarly to the mashing step in a traditional fermentation test, hydrolyzed just 38.5–47.2% of total sorghum starch to glucose. The initial procedure was simplified to contain only one liquefaction step, which did not influence subsequent saccharification. Thereafter, parameters such as temperature, pH, enzyme dosage, and saccharification time were optimized. Results showed that 91.2–97.5% of the total starch in 18 sorghum hybrids had been hydrolyzed to glucose using the following conditions: liquefaction at 86 °C for 90 min, 20 μL of α-amylase per 30 g of sample; pH adjustment by adding 50 μL of 2 M acetate buffer at pH 4.2 to each microtube; saccharification at 68 °C for 90 min, 200 μL of amyloglucosidase per 30 g of sample. There were strong linear correlations between completely hydrolyzed starch (CHS) from SSM and ethanol yields from both traditional ( R 2 = 0.86) and simultaneous saccharification and fermentation (SSF, R 2 = 0.93) procedures. CHS was a better indicator for predicting ethanol yield in fermentation than total starch.

Optimisation of a Mashing Program for 100% Malted Buckwheat

The objective of this study was to develop a temperature programmed mashing profile for 100% buckwheat malt. Both standard brewing methods and a rheological tool (Rapid Visco Analyser) were used to characterise worts and mashes. An optimal grist: liquor ratio of 1:4 was observed. At this ratio, buckwheat malt showed a gelatinisation temperature of 67°C and barley malt 62°C. A one hour stand at 65°C exhibited higher FAN levels, fermentable extracts and lower viscosity values than stands at 67°C or 69°C, and was therefore used in further mashing trials. An extra mashing step of 30 min, at any of the tested temperatures, increased extract values a minimum of 4%, decreased viscosities a minimum of 0.20 mPas, and increased fermentable extracts 12%. Best results were obtained when a mashing-in temperature was used in the range of 35°C to 45°C. These mashing-in temperatures were used to design an optimal mashing procedure: 15 min at 35°C; 15 min at 45°C; 40 min at 65°C; 30 min at 72°C; 10 min at 78°C. This program showed higher extract values and fermentable extract values (72.7% and 49.9%) than obtained by congress mashing (65.3% and 40.0%), thus successfully optimising the mashing program.