The reason for the preferential use of finger millet (Eleusine coracana) in eastern African brewing

Finger millet (Eleusine coracana) is a cereal that is widely used as an ingredient for alcoholic beverages in Eastern Africa. However, the reason for its preferred use in brewing over other types of cereal is still unknown. In this study, we aim to clarify the reason for selective use of finger millet in Eastern African brewing, through a field survey and laboratory experiments. The field survey was conducted in a rural village of Tanzania, named Bupigu. In the village, finger millet was used to prepare four types of foods: ugali (stiff porridge), uji (thin porridge), togwa (saccharified beverage) and pombe (alcoholic beverage). Among them, pombe brewing was the principal method of utilization. In addition, the survey showed that the villagers recognize that finger millet is responsible for the strong taste of pombe. Furthermore, the laboratory experiment showed that the α‐amylase activity of finger millet is higher than that of other cereals cultivated in Eastern Africa, suggesting that finger millet is a preferable ingredient for enhancing the efficiency of ethanol production. In conclusion, this study demonstrated that the high amylase activity, which led to high ethanol concentrations in the alcoholic beverages, is a preferable characteristic of the finger millet.     

Production of indigenous alcoholic beverages in a rural village of Cameroon

In this study, the indigenous alcoholic beverages in a rural village of Cameroon were investigated. The technique for producing alcoholic beverages in the village was observed, and the concentrations of ethanol, glucose and lactic acid and the pH values during the course of production were measured using portable devices at the field site. Eight different kinds of alcoholic beverage (palm wine, palm spirits, raffia wine, cassava spirits, maize turbid beer, maize spirits, plantain wine and plantain spirits) were produced and consumed in the village. Of these beverages, palm wine, made from palm sap, was the most important alcoholic beverage in a villager's daily life. In addition, starch‐based alcoholic beverages were distilled rather than drunk directly. As germinated maize, which has a relatively low amylase activity, was used as an amylase source in production, starch‐based alcoholic beverages might need to be distilled to enhance the ethanol concentration. During the course of production, the pH was reduced using local techniques, which proved to be effective in preventing bacterial contamination. Copyright © 2014 The Institute of Brewing & Distilling     

The Occurrence of Beer Spoilage Lactic Acid Bacteria in Craft Beer Production

Beer is one of the world's most ancient and widely consumed fermented alcoholic beverages produced with water, malted cereal grains (generally barley and wheat), hops, and yeast. Beer is considered an unfavorable substrate of growth for many microorganisms, however, there are a limited number of bacteria and yeasts, which are capable of growth and may spoil beer especially if it is not pasteurized or sterile‐filtered as craft beer. The aim of this research study was to track beer spoilage lactic acid bacteria (LAB) inside a brewery and during the craft beer production process. To that end, indoor air and work surface samples, collected in the brewery under study, together with commercial active dry yeasts, exhausted yeasts, yeast pellet (obtained after mature beer centrifugation), and spoiled beers were analyzed through culture‐dependent methods and PCR‐DGGE in order to identify the contaminant LAB species and the source of contamination. Lactobacillus brevis was detected in a spoiled beer and in a commercial active dry yeast. Other LAB species and bacteria ascribed to Staphylococcus sp., Enterobaceriaceae, and Acetobacter sp. were found in the brewery. In conclusion, the PCR‐DGGE technique coupled with the culture‐dependent method was found to be a useful tool for identifying the beer spoilage bacteria and the source of contamination. The analyses carried out on raw materials, by‐products, final products, and the brewery were useful for implementing a sanitization plan to be adopted in the production plant.     

The pasting behaviour of lactic‐fermented and dried uji (an East African sour porridge)

The effects of sun‐, cabinet‐, and drum‐drying on the behaviour of submerged culture lactic‐fermented pure cassava, maize and finger millet and composites of maize–finger millet and cassava–finger millet were investigated in a Brabender amylograph. The cereal flours and maize–finger millet composite had higher onset and peak gelatinization temperatures but lower peak viscosities than cassava or cassava–finger millet composites. Fermentation alone or in combination with drying increased the viscosity of the flours, except for the fermented and drum‐dried cassava–finger millet composite flour. This increased viscosity of uji on fermentation and drying makes it more difficult to cook. Fermented and drum‐dried flours recorded high initial viscosities, at 30 °C, when the amylograph was switched on. Copyright © 2003 Society of Chemical Industry     

Rich nutrition from the poorest – Cereal fermentations in Africa and Asia

Cereal fermentations in Africa and Asia involve mainly the processing of maize, rice, sorghum and the millets. Lactic acid bacteria (Lactobacillus, Pediococcus), Enterobacter spp., yeasts (Candida, Debaryomyces, Endomycopsis, Hansenula, Pichia, Saccharomyces and Trichosporon spp.) and filamentous fungi (Amylomyces, Aspergillus, Mucor, and Rhizopus spp.) contribute to desirable modifications of taste, flavour, acidity, digestibility, and texture in non-alcoholic beverages (e.g., uji, and ben-saalga), porridges (e.g., mawè) and cooked gels (e.g., kenkey, idli, and mifen). In addition, alcoholic beverages (beers such as tchoukoutou and jnard; and spirits e.g. jiu) are obtained using malt, or using amylolytic mixed microbial starter cultures as generators of fermentable substrates. Wet processing, marketing of multi-purpose intermediate products, co-fermentation for texture and nutrition, and mixed culture fermentations as practiced in indigenous fermentation processes are of interest for industrial innovation and for better control of natural mixed culture fermentation systems. On the other hand, the nutritional properties of traditional cereal fermented products can be enhanced by increasing their nutrient and energy density, as well as by increasing their mineral status by combining mineral fortification and dephytinization.     

Comparison of rheological and colorimetric measurements to determine α-amylase activity for malt used for the beverage Bozo

In the current study, rheological and colorimetric methods were compared for determination of α-amylase activity of grain malt, used for Kyrgyz traditional fermented beverage Bozo. The highest α-amylase activity determined by colorimetric method was found in barley malt (32.83 A), followed by wheat (32.09 A), and was lowest in millet malt (10.82 A) and maize malt (10.76 A). Rheological parameters of millet porridge without and with malt were studied. The liquefaction effect of millet porridge after addition of malt was determined with rotational and oscillatory measurements. Results from statistical analysis (partial least squares regression) revealed that oscillatory rheological parameters (yield stress τ, deformation γ, and storage modulus G′) could be an effective indicator to predict the α-amylase activity of the investigated malt with R² = 0.9572. Consequently, rheological oscillatory measurements were recommended as an alternative tool to determine α-amylase activity of grain malt.     

Effect of drying lactic fermented uji (an East African sour porridge) on some carboxylic acids

Maize, finger millet, cassava, maize–finger millet and cassava–finger millet flours were fermented and sun‐, cabinet‐, or drum‐dried. Total titratable acidity (TTA), fixed acidity (FA), pH and carboxylic acids were determined. The TTA of the non‐fermented flours ranged from 0.22%(w/w) lactic acid in cassava to 0.36%(w/w) lactic acid in the maize–finger millet composite. After fermentation the TTA ranged from 3.26%(w/w) lactic acid in cassava–finger millet to 4.54% in maize‐finger millet while FA ranged from 2.86% in cassava–finger millet to 4.26% in cassava and maize–finger millet. Fermentation decreased the pH from about 5.5 to 3.7–4.1. Drying did not change the pH but TTA decreased by 20–60%. Acetic acid levels in the fermented slurries varied from 0.80 to 0.95 µg per 5 µg while those of hexanoic acid varied from 0.9 to 1.8 µg per 5 µg. Propionic acid was absent in the fermented slurries. Acetic and formic acids were completely lost when the fermented slurries were dried. On average hexanoic acid losses on drying varied from 33% in maize to 91% in cassava fermented slurries. These losses were not significantly influenced by the drying system. In sensory evaluation panellists could not detect flavour loss as a result of drying. © 2000 Society of Chemical Industry     

A review of traditional fermented foods and beverages of Zimbabwe

Several traditional fermented foods and beverages are produced at household level in Zimbabwe. These include fermented maize porridges (mutwiwa and ilambazi lokubilisa) fermented milk products (mukaka wakakoralamasi and hodzeko) non-alcoholic cereal-based beverages (mahewu, tobwa and mangisi) alcoholic beverages from sorghum or millet malt (doroluthwala and chikokivana) distilled spirits (kachasu) and fermented fruit mashes (makumbi). There are many regional variations to the preparation of each fermented product. Research into the processing technologies of these foods is still in its infancy. It is, therefore, important that the microbiology and biochemistry of these products, as well as their technologies be studied and documented in order to preserve them for future generations. This article reviews the available information regarding traditional fermented foods in Zimbabwe and makes recommendations for potential research areas.     

Is it possible to create an innovative craft durum wheat beer with sourdough yeasts? A case study

Craft beer is often produced as a non‐filtered, unpasteurized and bottle re‐fermented beer, whose production is aimed at maintaining original sensory characteristics. The intention of most micro‐breweries is to meet these requirements in producing a high‐quality beer. In Italy, as well as in Sardinia, the number of micro‐breweries is increasing. In an attempt to make this product more original, new strains of Saccharomyces cerevisiae were selected. Sourdough yeasts were used as an alternative source of starters for beer production. In this particular work, two wheat beers were compared, one brewed with an autochthonous yeast isolated from sourdough and the other brewed with a commercial yeast normally used in Italian micro‐breweries. The wheat beer fermented with the autochthonous yeast had the highest ethanol content, the lowest pH and the highest content of esters and alcohols. From a sensory point of view the two beers showed significant differences in the triangle test, but were not significantly different in the paired test with preference. Copyright © 2015 The Institute of Brewing & Distilling     

Effect of urea and by-products on the in-vitro fermentation of untreated and urea treated finger millet (Eleusine coracana) straw

The in-vitro fermentation characteristics of untreated and 50 g litre^?1 urea-treated finger millet (Eleusine coracana) straw with four supplements (urea, rice bran, cottonseed and groundnut cakes) at three different ratios of straw: supplement were investigated. Gas production was greater from treated than untreated straw; groundnut cake was the most rapidly fermented supplement followed by cottonseed cake and rice bran. Urea incubated alone inhibited gas production. Untreated and treated straws were incubated with 22, 30 and 37 g rumen degradable nitrogen from the supplements per kg organic matter digested. Significant (P < 0.05) positive interactive effects on gas production were observed with untreated straw at all three levels of groundnut cake supplementation after 12, 52 and 166 h incubation. Similar interactions were observed for cottonseed cake supplementation of untreated straw and groundnut cake supplementation of treated straw, although statistical significance was not achieved for all supplementation levels at the three times for which data were analysed. No consistent significant interactive effects in gas production were observed between cottonseed cake and treated straw. Rice bran inhibited gas production after 12 h but, subsequently, had little effect on either type of straw. Urea inhibited the gas production from both straws at all three ratios of supplementation. Urea also significantly reduced dry matter disappearance of treated straw at two of three levels of urea supplementation. Interactive effects on gas production were most pronounced in the early stages fermentation and appeared to be related to the high content of highly fermentable material particularly in groundnut cake but also in cottonseed cake.     

Production of high energy density fermented uji using a commercial alpha-amylase or by single-screw extrusion

The effects of alpha-amylase and extrusion on the viscosity and energy density of uji, a spontaneously fermented thin porridge from different combinations of maize, finger millet, sorghum and cassava, were investigated. Fermentation alone was not able to reduce the viscosity of uji, but addition of 0.1-2.1 ml/100 ml alpha-amylase to the fermented slurry or extrusion of the fermented and dried flour at 150-180°C and a screw speed of 200 rpm reduced the viscosity of 20 g/100 ml uji from 6000-7000 to 1000-2000 cP, measured at 40°C and a shear rate of 50 s⁻¹. The amount of flour required to make uji could thus be increased by a factor of 2.0-2.5 and consequently it was possible to produce uji with acceptable energy densities (0.6-0.8 kcal/g) for child feeding.     

Bioprospecting for brewers: Exploiting natural diversity for naturally diverse beers

The burgeoning interest in archaic, traditional, and novel beer styles has coincided with a growing appreciation of the role of yeasts in determining beer character as well as a better understanding of the ecology and biogeography of yeasts. Multiple studies in recent years have highlighted the potential of wild Saccharomyces and non-Saccharomyces yeasts for production of beers with novel flavour profiles and other desirable properties. Yeasts isolated from spontaneously fermented beers as well as from other food systems (wine, bread, and kombucha) have shown promise for brewing application, and there is evidence that such cross-system transfers have occurred naturally in the past. We review here the available literature pertaining to the use of nonconventional yeasts in brewing, with a focus on the origins of these yeasts, including methods of isolation. Practical aspects of utilizing nondomesticated yeasts are discussed, and modern methods to facilitate discovery of yeasts with brewing potential are highlighted.     

非酿酒酵母产生的β-葡萄糖苷酶在发酵酒中的应用研究进展

β-葡萄糖苷酶对糖苷键的水解作用已被广泛应用于酿酒、茶增香、保健品开发等领域.发酵环境中非酿酒酵母产生的β-葡萄糖苷酶活力高于酿酒酵母,可在酿酒酵母酶活力不足时进行补充.本文对发酵过程中不同的影响因素如酵母合成和释放β-葡萄糖苷酶的能力、发酵环境中的温度、酸碱度和可发酵糖浓度等对β-葡萄糖苷酶活力的影响进行了综述,并对...     

Brewing with Rice Malt — A Gluten‐free Alternative

The preparation of beer‐like beverages with rice malt as the only raw material is reported. Several tests were performed on a laboratory scale and in a 25 L‐capacity pilot plant. Both the decoction and the infusion procedure were tested; malt and water were mixed in a ratio 1:3.5 for both methods and the mash was brewed without adding exogenous enzymes. The obtained worts were fermented using bottom fermenting yeasts, while “beers” were re‐fermented utilizing top fermenting yeasts and adding either sterile wort or sugar. A maximum ethanol of 4.5% vol. was obtained after the primary fermentation from an initial wort with an original gravity of 11.8°Plato. All parameters of the beer were found to be acceptable using a standard beer analysis. Owing to a suitable hop addition, an aroma very similar to that of a normal beer was obtained.     

Biosynthesis of higher alcohol flavour compounds by the yeast Saccharomyces cerevisiae: impact of oxygen availability and responses to glucose pulse in minimal growth medium with leucine as sole nitrogen source

Higher alcohol formation by yeast is of great interest in the field of fermented beverages. Among them, medium‐chain alcohols impact greatly the final flavour profile of alcoholic beverages, even at low concentrations. It is widely accepted that amino acid metabolism in yeasts directly influences higher alcohol formation, especially the catabolism of aromatic and branched‐chain amino acids. However, it is not clear how the availability of oxygen and glucose metabolism influence the final higher alcohol levels in fermented beverages. Here, using an industrial Brazilian cachaça strain of Saccharomyces cerevisiae, we investigated the effect of oxygen limitation and glucose pulse on the accumulation of higher alcohol compounds in batch cultures, with glucose (20 g/l) and leucine (9.8 g/l) as the carbon and nitrogen sources, respectively. Fermentative metabolites and CO₂/O₂ balance were analysed in order to correlate the results with physiological data. Our results show that the accumulation of isoamyl alcohol by yeast is independent of oxygen availability in the medium, depending mainly on leucine, α‐keto‐acids and/or NADH pools. High‐availability leucine experiments showed a novel and unexpected accumulation of isobutanol, active amyl alcohol and 2‐phenylethanol, which could be attributed to de novo biosynthesis of valine, isoleucine and phenylalanine and subsequent outflow of these pathways. In carbon‐exhausted conditions, our results also describe, for the first time, the metabolization of isoamyl alcohol, isobutanol, active amyl alcohol but not of 2‐phenylethanol, by yeast strains in stationary phase, suggesting a role for these higher alcohols as carbon source for cell maintenance and/or redox homeostasis during this physiological phase. Copyright © 2014 John Wiley & Sons, Ltd.     

A study of beer bitterness loss during the various stages of the Romanian beer production process

Beer is one of the oldest known alcoholic beverages produced by a yeast fermentation of a cereal extract that was germinated in water beforehand. The bitter taste of beer comes from the group of substances introduced during wort boiling, which are the extracted components of hops. The aim of this study was to determine some characteristics of beer (original extract, alcohol content, colour, pH, total acidity, carbon dioxide and bitterness values) during the three stages of the beer production process in a typical Romanian brewery. Measurements were carried out on 60 samples of beers, 10 measurements for each step of the process examining wort, unfiltered fermented beer and bottled beer (final product) from two different types of beer (light and dark). Statistical process control of the beer was performed. Losses in the bitterness units during the production process were between 24.7 and 41.54%, reported in terms of final product. Copyright © 2013 The Institute of Brewing & Distilling     

Mycotoxins in South African traditionally brewed beers

Traditionally brewed alcoholic beverages are regularly consumed by most ethnic black South Africans. Maize and barley, both of which are used for producing locally brewed alcoholic beer, are frequently contaminated by mycotoxin-producing moulds. The study was undertaken to investigate whether these toxins are present in raw grains and the traditional beers imbibed by the local black African population. It was established that the raw ingredients (sorghum, sorghum malt grains, maize grits), commercially produced traditional beers (Utshwala and Utshwala special) and home-brewed beers (Umqombotha, Isiqatha, Imfulamfula) were contaminated by bacteria and fungi (both yeasts and moulds). The contaminating moulds were isolated and identified. The contaminated samples were analysed for aflatoxins B 1 , B 2 , G 1 and G 2 , zearalenone, citrinin, deoxynivalenol, and ochratoxin A using a multi-mycotoxin thin-layer chromatography screening method and the toxins were quantified by high-performance liquid chromatography. Grain samples were infected by Aspergillus flavus , A. alliaceus , A. clavatus , Penicillium spp., Rhizopus spp. and Mucor spp. Sorghum malt grain samples contained the toxin zearalenone. No mycotoxin-producing fungi were present in the fermented beers but two of six commercial beer samples contained aflatoxins (200 and 400 μgl -1 ) and 45% (13 of 29) of the home-brewed beers had zearalenone (range 2.6-426 μg l -1 ) and/or ochratoxin A (3-2340 μg l -1 ).     

Investigation of ethyl carbamate levels in some fermented foods and alcoholic beverages

An analytical procedure has been developed for the determination of trace amounts of ethyl carbamate in fermented foodstuffs and alcoholic beverages. Concentrations were generally below the 1-5 micrograms/kg detection limit in bread, cheese, yoghurt, beer, gin and vodka. Higher concentrations were found in the other alcoholic beverages examined, which included whisky, fruit brandy, liqueur, wine, sherry and port.     

Effect of Germination and Fermentation on in vitro Starch and Protein Digestibility of Pearl Millet

Germination of pearl millet grain for 24 hr significantly improved its in vitro starch and protein digestibility. Fermentation of pearl millet sprouts by mixed culture combinations of yeasts and bacteria (Saccharomyces diastaticus and Lactobacillus brevis; Saccharomyces diastaticus and Lactobacillus fermentum; Saccharomyces cerevisiae and Lactobacillus brevis; and Saccharomyces cerevisiae and Lactobacillus fermentum) resulted in a significant increase in protein and starch digestibility. The pearl millet sprouts fermented with mixed culture containing S. diastaticus and L. brevis had the highest in vitro starch digestibility, while the sprouts fermented with the culture containing 5. cerevisiae and L. fermentum had the highest in vitro protein digestibility.