Two highly purified arabinoxylan preparations of different molecular w
eight (HMW, [eta] = 5.48 dl/g and LMW, [eta] = 3.69 dl/g) were used to
study the effect of these water-soluble polysaccharides on the bread-
making quality of two wheat flours: a Canada western red spring (CWRS)
composite sample and a Canada prairie spring (CPS), cv. HY 368. Both
preparations significantly increased the farinograph water absorption
and the dough development time for the two flours; the HMW arabinoxyla
ns exerted significantly (P < 0.01) greater effects than the LMW prepa
ration. The HMW arabinoxylans maximally improved the loaf volume of CW
RS and CPS breads at a level of 0.5% (w/w) supplementation. The LMW ar
abinoxylans maximally increased the loaf volume of CWRS and CPS breads
at 0.7 and 1.1% (w/w), respectively. Breads containing HMW arabinoxyl
ans retained significantly (P < 0.01) more water than the breads with
LMW polymers at 0.5-0.9% (w/w) supplementation levels. Because of thei
r higher moisture content the arabinoxylan-fortified breads exhibited
a greater rate of starch retrogradation as assessed by calorimetry. Ne
vertheless, these breads had softer breadcrumbs than the controls; bre
ads fortified (0.3-0.9% w/w) with HMW arabinoxylans were significantly
(P < 0.01) less firm than those with LMW polymers over the 7-day stor
age period.