Characteristics of Starch in Argentinean Malting Barley
MBAA TQ vol. 44, no. 3, 2007, pp.
170-175 |
VIEW ARTICLE Olivia V. L�pez (1), Mar�a A. L�zzari (2), and Mar�a
S. Rodr�guez (1). 1. Department of Chemistry, Universidad Nacional del
Sur, Avda Alem 1253, 8000 Bah�a Blanca, Argentina. 2. LAHBIS,
Department of Agronomy, Universidad Nacional del Sur, San Andr�s 700,
8000 Bah�a Blanca, Argentina.
Abstract
Sixteen samples of malting barley grown in the Buenos Aires
Province of Argentina were selected for this study. Starch was isolated
and purified using a modified version of the Morrison method. The starch
concentration in the samples ranged from 53.2 to 63.3%. The starch samples
were characterized physicochemically, and the following results were
obtained: 1) the concentration of lipids, phosphorus, and nitrogen was too
low; 2) the values for apparent amylose ranged from 19.0 to 23.9%, whereas
the values for total amylose ranged from 23.6 to 31.2; 3) the starch had a
bimodal granule size distribution�type A (big and lenticular) and type B
(small and irregular or spherical); 4) the gelatinization temperature
ranged from 62.18 to 64.68�C; 5) amylopectin was responsible for the
crystallinity of starch granules; and 6) the granules were birefringent.
The last property disappeared when starch was heated above its
gelatinization temperature.
Keywords: malting barley, physicochemical characteristics,
quantization, starch
S�ntesis
Se estudiaron diecis�is muestras de cebada de malteo cultivado en
la provincia de Buenos Aires en Argentina, separ�ndolas de su almid�n y
purific�ndolas usando una versi�n modificada del m�todo de Morrison. Las
concentraciones de almid�n variaron de 53.2% a 63.3%. Las muestras de
almid�n se caracterizaban f�sico-quimicamente con los sigui�entes
resultados: 1) las concentraciones de l�pidos, f�sforo y nitr�geno fueron
demasiadas bajas; 2) la concentraci�n de amilosa aparente vari� de 19.0% a
23.9%, mientras que la amilosa total vari� de 23.6% a 31.2%; 3) el almid�n
tuvo una distribuci�n de tama�o de granulo bimodal�tipo A (grande y
lenticular) y tipo B (peque�o e irregular o esferico); 4) la temperatura
de gelatinizaci�n vari� de 62.18�C a 64.68�C; 5) la amilopectina fue la
responsable por la critalinidad de los gr�nulos de almid�n; y 6) los
gr�nulos eran birefringentes. Esta �ltima propiedad desapareci� al
calentar el almid�n por encima de su temperatura de gelatinizaci�n.
Palabras claves: almid�n, caracter�sticas f�sico-qu�micos, cebada de
malteo, cuantizaci�n
