Chemical Compositions and Resistant Starch Content in Starchy Foods

Resistant Starch (RS) is one of nature’s most interesting bioactive compounds. There is a wide variety of starchy food plants in Thailand that are good sources of RS, but they have not been well studied. As such, this study was carried out to investigate the potential food source of RS. Twenty-two promising food plants were selected. The samples included (1) cereals comprised of five long grain rice of O. sativa L. and sweet corn, (2) six species of root and tuber crops, (3) green banana fruits (Musa sapientum L.) composed of ABB group, AAB group and AAA group at the first stage of ripening and (4) legume seeds included cowpea seeds (3 different cultivars), red bean, red kidney bean and mung bean. All food plants were determined for chemical compositions, resistant starch, non-resistant starch, total starch and amylose content. The study found that the starchy foods varied in their chemical compositions. The major composition of all foods was carbohydrate ranging between 58.19 (in black speck cow pea) and 87.21% (in cassava root), whilst the fat, ash and fiber were observed only in small quantities. The protein content was highest in legume seeds (20.78 to 27.22%). For the study on starch compositions, green bananas contained highest amount of resistant starch ranging between 35.14 and 45.87%, indicating that more than a half of total starch in banana RS content varying from 35.14 to 45.87%, whereas the RS content of legumes ranging from 2.33 to 10.63% and 1.16 to 4.85% in cereal grains. Most of the starchy food plants contained moderate to high level of amylose (11.45-34.85%), except the waxy rice (2.72%).