3.2. Insoluble and soluble dietary fibre content of boiled and canned
legumes
The measured IDF and calculated SDF values for boiled and
canned legumes are presented in Table 3. The results show that
IDF values in boiled legumes ranged from 2.65% for green beans to
8.89% for red kidney beans, and in canned legumes from 1.96%
green beans to 6.42% for yellow chickpeas.
The IDF represents at least 60% of TDF for all tested legumes
with the remaining representing the SDF fraction. ANOVA was
used to compare between IDF content in boiled versus canned
legumes. The values were significantly higher in boiled
legumes by 1.7 g/100 g compared to their canned equivalents
(p = 0.02). Similar findings were observed in a previous study
that found that IDF in boiled soaked beans was higher than
in canned beans with a difference of 1 g/100 g (Kutos et al.,
2003).
However, the proportion of IDF:SDF did not vary significantly
with cooking method (p = 0.3), indicating that both fractions
(soluble and insoluble) decrease by the same proportion during
canning and boiling. This is in contrast to a previous study that
found changes in fibre fractions of green beans after cooking and
autoclaving (Anderson and Clydesdale, 1980).