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Enzymic Modification of Millet Varieties (Sossat and Pennisetum maiwa) with Similar Nitrogen Contents During Malting

MBAA TQ vol. 44, no. 2, 2007, pp. 98-103  |  VIEW ARTICLE

L. O. Eneje (1), F. J. C. Odibo (2), R. C. Agu (3), G. H. Palmer (4), and A. H. Ugwu (5). 1. Department of Applied Microbiology and Brewing, Enugu State University of Science and Technology, Enugu, Nigeria. 2. Department of Applied Microbiology and Brewing, Nnamdi Azikiwe University, Awka, Nigeria. 3. The Scotch Whisky Research Institute, Research Park Avenue, Riccarton, Edinburgh, Scotland. 4. ICBD, Heriot-Watt University, Riccarton, Edinburgh, Scotland. 5. Department of Industrial Mathematics, Enugu State University of Science and Technology, Enugu, Nigeria.

Abstract
Millet varieties (Pennisetum maiwa and Sossat) with similar nitrogen contents were malted for 6 days, and enzymic modification of their endosperm materials was evaluated. The pattern of proteolysis during the malting process appeared to be different for the two millets studied, but the trend in the production of some products of proteolysis was similar. P. maiwa had faster initial proteolytic activity than Sossat, but Sossat achieved a higher level of proteolysis than P. maiwa as germination progressed. The higher proteolysis that occurred in Sossat did not influence the development of diastatic enzyme activity, but rather was associated with Sossat malt producing more soluble nitrogen hydrolysis products, such as free amino nitrogen (FAN), than did P. maiwa malt, and releasing more cold water soluble nitrogen (CWSN) than did P. maiwa. However, both millet varieties produced cold water extract (CWE) and total soluble nitrogen (TSN) at similar levels. Although Sossat produced greater amounts of FAN products in both ninhydrin and 2,4,6-trinitrogen benzene sulphonic acid (TNBS) assays than did P. maiwa, P. maiwa malt released more peptide nitrogen (PN) into the wort than did Sossat malt. It would appear from this study that the main difference between these two millet varieties with similar nitrogen contents was in peptide release, which influenced the fermentation pattern of the worts of P. maiwa and Sossat. The wort made from P. maiwa, which released more peptides in its wort, also had faster fermentation than the wort made from Sossat malt and produced a slightly higher amount of alcohol.

Keywords: diastatic power, fermentation, malting, mashing, millet, proteolysis, sorghum

 

S�ntesis
Variedades de mijo, tambi�n conocido como �trigo candeal� (Pennisetum maiwa y Sossat) con contenidos de nitr�geno similares, fueron malteados durante seis d�as para evaluar la modificaci�n enzim�tica de su endosperma. El patr�n de la prote�lisis durante el proceso de malteo fue diferente para las dos variedades estudiadas, pero la tendencia de la formaci�n de algunos productos de la prote�lisis s� fue similar. P. maiwa inici� la actividad proteol�tica m�s r�pidamente que Sossat, pero Sossat alcanz� un mayor nivel de prote�lisis que P. maiwa a lo largo de la germinaci�n. La mayor actividad proteol�tica en Sossat no afect� el desarrollo de la actividad diast�sica, m�s bien se relacion� con un mayor contenido de nitr�geno soluble en la malta de Sossat, tal como alfa amino nitr�geno libre (FAN), como tambi�n form� m�s nitr�geno soluble en agua fr�a (CWSN) que la malta de P. maiwa. Sin embargo, ambas variedades alcanzaron niveles similares de extracto en agua fr�a (CWE) y de nitr�geno soluble total. A pesar que Sossat produjo mayor cantidad de productos FAN (tanto en an�lisis mediante ninhidrina y de �cido 2,4,6-trinitr�geno benceno sulf�nico) que la P. maiwa, la malta de P. maiwa produjo m�s nitr�geno pept�dico en el mosto. Pareciera que la diferencia principal entre estas dos variedades de mijo (con niveles similares de nitr�geno) estuvo en la producci�n pept�dica en el mosto, lo que afect� los perfiles de fermentaci�n de ambos mostos. El mosto hecho con P. maiwa (con mayor contenido pept�dico) tuvo una fermentaci�n m�s r�pida que la de la malta de Sossat, y tambi�n produjo mayor cantidad de alcohol.

Palabras claves: fermentaci�n, maceraci�n, malteo, mijo, poder diast�sico, prote�lisis, sorgo

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