Eh. Mansour et Ah. Khalil, REDUCTION OF RAFFINOSE OLIGOSACCHARIDES IN CHICKPEA (CICER-ARIETINUM)FLOUR BY CRUDE EXTRACELLULAR FUNGAL ALPHA-GALACTOSIDASE, Journal of the Science of Food and Agriculture, 78(2), 1998, pp. 175-181
The efficiency of crude extracelluar alpha-galactosidases from Cladosp
orium cladosporides, Aspergillus oryzae and A niger in reducing the ra
ffinose and stachyose content in chickpea flours was studied and compa
red with other traditional treatments. The optimum pH for alpha-galact
osidase activity was found to be 4.5 for A oryzae and 5.0 for Cl clado
sporides and A niger, while the optimum temperature of enzyme activity
was 40 degrees C for Cl cladosporides and 50 degrees C for A oryzae a
nd A niger. The specific activities of alpha-galactosidase from Cl cla
dosporides, A oryzae and A niger were 3.35, 3.94 and 5.94 units mu g(-
1) protein, respectively. The enzyme activity was stable between pH 4.
0 and 7.0 for A oryzae and A niger and between pH 5.0 and 7.0 for Cl c
ladosporides. The enzymes were thermostable when incubated at temperat
ure ranges of 40-60''C for C1 cladosporides and 40-50 degrees C for A
oryzae and A niger. The optimum conditions for removing the raffinose
and stachyose were obtained by incubating chickpea flours with 30 mi o
f crude fungal alpha-galactosidase extract (290, 210 and 130 units ml(
-1) for C1 cladosporides, A oryzae and A niger, respectively) for 3 h
at the optimum conditions of each strain. Crude fungal alpha-galactosi
dases reduced the raffinose oligosaccharides content in chickpea flour
s by 100%, while germination reduced the raffinose content by 69% and
stachyose content by 75%. Other traditional techniques reduced the raf
finose content by 13-49% and stachyose content by 10-32%. (C) 1998 Soc
iety of Chemical Industry.