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