Abstract
[Purpose]
Resistance starch (RS) is known as indigestive starch and improving gut microbiota. But there is little knowledge of a change in RS in food by cooking and during preservation. So various starch, just after the heating of a food and back RS heated with a microwave again after room temperature leaving for 1 hour were measured.
[Methods]
A bunch of dry spaghetti (100g) was heated for 7 minutes by boiling hot water of 1L. Other carbohydrate rich foods were cooked as follows: dry noodle (90g), boiled noodles (180g) and raw Chinese noodles (141g) respectively. The cooked foods were left in the room temperature for 1 hour. Rice(200g) was added 1.5 times of water and cooked by a electric rice cooker. After leaving the room temperature for 1 hour, it was heated with a microwave. And then it was poured of boiling water and did room temperature leaving for 10 minutes. Cooked rice was preserved in a freezer for 24 hours. The freezing rice was heated by a microwave. And then it was leaving for 4 hours in room temperature after re-heating. Sample preparation was followed as Kamei1) , and RS was measured by AOAC method.
[Results]
RS was increased 2.0 times in spaghetti by 1 hour room temperature leaving. Dry noodle, boiled noodles and raw Chinese noodles were increased 1.5, 1.1, 2.2 times respectively. RS increased 2.9 times in cooked rice after 1 hour leaving at room temperature. Microwave re-heat and pouring boiled water were not decreased RS (93%, 95% to 1 hour room temperature leaving). RS was increased 2.1 after 24 hours freezer preservation. RS was increased after microwave re-heart (117%), and RS was still increased 4 hours room temperature after microwave re-heat (139%). Those results indicate RS is formed cooling, and RS is not gelatinization microwave re-heat or adding boiled water.
1) Kamei et al, Miyagi University of Education, Bulletin (2016) 50, 165-170.
