Studies on mashing methods for beer brewing with sorghum

Summary Five mashing methods were tested on two varieties of sorghum malt. The highest amounts of reducing sugars were produced in second-stage decoction (13.6 mg/ml) and third-stage decoction (13.8 mg/ml). The downward infusion method yielded the lowest amount of reducing sugar (12.3 mg/ml). The two-stage decoction mashing yielded the lowest amount of protein (1.3 mg/ml). The three-stage decoction mashing showed that increasing the holding time for saccharification and dextrinization increased the reducing sugar (18.6 mg/ml). There was little increase in the protein. A change in conventional temperature resulted in a reduction in the reducing sugar produced. Increase in mash concentration showed a corresponding increase in reducing sugars. In terms of holding time, the upward infusion method showed an increase in reducing sugars with very little change for the downward infusion method. There was no significant change in the protein content of the worts.

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Resumen Se estudiaron cinco métodos de obtención de pulpa para la elaboración de cerveza a partir de dos variedades de malta de sorgo. La cocción en dos y tres fases produjo la mayor cantidad de azúcares reductores (13.1 mg/ml y 13.8 mg/ml, respectivamente.) La menor cantidad de estos (12.3 mg/ml) se obtuvo en el proceso de infusión descendente. La cocción en dos etapas generó la menor cantidad de proteínas. Estudios posteriores sobre la cocción en tres etapas mostraron que un incremento en el tiempo de hidratación, en el cual tiene lugar la saccarinización y dextrinación del almidón, incrementó notablemente la cantidad de azúcares reductores y de forma a penas apreciable la fracción proteica. Cambios en la temperatura convencional del proceso resultaron en una disminución de los azúcares reductores producidos. Al incrementar la concentración de pulpa se obtuvo un aumento paralelo en la producción de azúcares reductores. El estudio del efecto de la variación del tiempo de hidratación en los métodos de infusión mostró que los azúcares reductores aumentaban para el método de infusión ascendente y no experimentaban practicamente ningún cambio para la infusión descendente; asimismo no se observó ningún cambio significativo en la fracción proteica del mosto.

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Résumé Cinq méthodes de brassage ont été testées sur deux variétés de malt de sorghum. La plus grande quantité de sucres réducteurs a été produite dans le deuxième étage de la décoction (13.6 mg ml^–1) et dans le troisième étage de la décoction (13.8 mg ml^–1). Le méthode par infusion à flux descendant a produit la quantité la plus faible de sucres réducteurs (12.3 mg ml^–1). Le brassage par décoction en deux étages a produit la quantité la plus faible de protéines (1.3 mg ml^–1). Des études complémentaires sur le brassage par décoction en 3 étages ont révélé qu'une augmentation du temps de saccharification et de dextrinisation entraînait une augmentation des sucres réducteurs (18.6 mg ml^–1). Il n'y avait dans ce cas que peu d'augmentation de la teneur en protéines. Le changememt de la température conventionnelle a entraîné la diminution de la production de sucres réducteurs. Des études complémentaires sur la durée des infusions à flux ascendant et à flux descendant ont montré une augmentation des sucres réducteurs pour la méthode par infusion à flux ascendant et très peu de changement pour la méthode par infusion à flux descendant. Il n'y a pas eu de changements significatifs dans les protéines du moût.

     

Entomopathogenic symbiotic bacteria,Xenorhabdus and Photorhabdus of nematodes

Xenorhabdus and Photorhabdus species are entomopathogenic bacteria with a wide insect host range, that belong to the family Enterobacteriaceae. Xenorhabdus and Photorhabdus species symbiotically associate with nematodes of the families Steinernematidae and Heterorhabditidae respectively. The factor(s) determining the symbiotic interaction between nematodes and bacteria are yet to be identified. Xenorhabdus and Photorhabdus species exist in two main phenotypic forms, a phenomenon known as phase variation. The phase I (or primary form) varies from phase II (or secondary form) in certain physiological and morphological characteristics. There is no variation in the DNA integrity of phase I and phase II and this supports epigenetic regulatory mechanism in phase variation. Certain pathogenic determinants such as pili, lipopolysaccharides and toxins contribute to the pathogenicity of Xenorhabdus and Photorhabdus species, and both appear to be equally pathogenic to insects. The observed similarity in their virulence to insect hosts may reflect possible in vivo conversion of phase II to phase I, however the host cellular invasion and virulence is yet to be properly understood. The virulence of Xenorhabdus variants varies among insects apparently due to factors which include the feeding habits of the insects. The molecular mechanism and biological significance of phase variation are presently unknown.     

Physiological variants of Saccharomyces cerevisiae and Kloeckera apiculata from palm wine and cashew juice

Physiological variants of Saccharomyces cerevisiae and Kloeckera apiculata have been identified in oil palm wine and cashew juice from Nigeria. Genomic DNA from the four S. cerevisiae variants had a % G + C of 36–41% while that of K. apiculata was 32.2%. Fermentation of cashew juice produced wine of alcoholic contents of 10% with S. cerevisiae , 8% with K. apiculata and 9.3% with both yeasts simultaneously. and accepted 31 August 1989     

Sorghum: a cereal with lager beer brewing potential

The potential of sorghum as an alternative substrate for lager beer brewing was recognized over five decades ago. Factors which appear to influence brewing with sorghum include: the variety of sorghum, storage time, steep period, germination time, duration and levels of temperature-time sequence of the kilning cycle and temperature-time regimes during mashing. Malts from sorghum varieties that have high diastatic power, amylase and starch contents are desirable. Soluble and insoluble amylases in grain sorghum contribute towards the hydrolysis of grain constituents during mashing. Optimizing conditions for malting, mashing and fermentation are therefore necessary for the production of acceptable sorghum lager beer. This review aims to update research results on lager beer brewing with sorghum.     

Use of unmalted sorghum as a brewing adjunct

Hydrolysis of three varieties of unmalted sorghum by endogenous amylases produced sufficient maltose and glucose for subsequent brewing of beer. The optimal temperature and pH of the sorghum amylase activities varied between the three varleties. -Amylase was optimal when used at 60°C and pH 5 for two varieties but at 60°C and pH 6 for another. The optimal -amylase activity was between about 72°C and 75°C for all the sorghum varieties. The activities of the amylases differed considerably between the species.

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Résumé L'hydrolyse de trois variétés de sorghum non maltés par des amylases endogènes produit suffisamment de maltose et de glucose pour la fermentation ultérieure du moût. Les températures et pH optimum des activités amylolytiques du sorghum varient selon la variété. Pour deux variétés, l'activité -amylolytique est optimal lors de son utillsation à 60°C et à pH 5, tandis qu'elle est optimale à 60°C et à pH 6 pour la troistème. L'activité -amylolytique est optimal à environ 72 à 75°C pour toutes les variétés de sorghum. Les activités amylolytiques varient considérablement selon les espèces.

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This work was carried out at the Department of Microbiology, University of Nigeria, Nsukka, Nigeria.     

Production of burukutu with Saccharomyces cerevisiae variants

Summary Physiological variants of Saccharomyces cerevisiae have been identified from burukutu and Raphia palm wine. Genomic DNA from the three S. cerevisiae variants had 38–40% G+C. Mixed fermentation of burukutu wort with each of the S. cerevisiae variants and bacterial species (Lactobacillus brevis, L. plantarum and Lactococcus lactis) produced burukutu of 3.1–4.0% alcoholic content.     

Physiological variants of Saccharomyces cerevisiae and Kloeckera apiculata from palm wine and cashew juice

Physiological variants of Saccharomyces cerevisiae and Kloeckera apiculata have been identified in oil palm wine and cashew juice from Nigeria. Genomic DNA from the four S. cerevisiae variants had a % G + C of 36-41% while that of K. apiculata was 32.2%. Fermentation of cashew juice produced wine of alcoholic contents of 10% with S. cerevisiae, 8% with K. apiculata and 9.3% with both yeasts simultaneously.