Effects of legume processing on calcium, iron and zinc contents and dialysabilities

Legumes are a good source of calcium, iron and zinc, but are also a source of phytates and dietary fibre components that can negatively affect the bio availability of these minerals. To estimate the latter, an in vitro dialysi s method can be applied that gives the dialysability of a mineral as an est imate of its availability for absorption. Calcium, iron and zinc contents a nd dialysabilities in three legumes (beans, chickpeas and lentils) and the effects of cooking treatments and industrial processing on these parameters were studied. Beans had the highest calcium content (1.54 g kg(-1) dry mat ter (DM)) and chickpeas the lowest iron content (46.9 mg kg(-1) DM), whilst the zinc contents were similar in all three raw legumes (33.7-36.9 mg kg(- 1) DM). Traditional and microwave cooking reduced the mineral contents by 9 .7-36.4% for calcium, 14.2-31% for iron and 11.1-28.9% for zinc. The dialys abilities of calcium with respect to the values for the raw products were a lso reduced by these cooking techniques. Industrially processed legumes had higher dialysabilities of calcium, iron and zinc than traditionally or mic rowave cooked legumes. (C) 2001 Society of Chemical Industry.