Dietary fibre content of dry and processed beans

Common beans (Phaseolus vulgaris L.) are a good source of protein, vitamins, minerals and especially dietary fibre. As beans are never eaten raw, the effects of soaking, cooking, soaking–cooking and canning on soluble, insoluble and total dietary fibre contents of beans are studied. Total dietary fibre content was determined by enzyme-gravimetric method. The fraction of insoluble dietary fibre was corrected for the content of resistant starch, determined as part of the total starch in insoluble fibre. The results indicate that thermal processing decreased the insoluble fibre content, and consequently the total dietary fibre content of beans. Soaking and cooking of beans significantly (P⩽0.05) increased the resistant starch content. The data on dietary fibre content of processed food are much more relevant than those of raw food. Thus food composition tables should contain as much data on processed food as possible.