An innovative method for heating the core of starchy food by microwave irradiation.

摘要

A method using microwave heating at 2450 MHz to produce a new type of noodle that is pre-cooked (gelatinized) in the centre only, leaving the surface uncooked (ungelatinized), was investigated. Temp. distribution in the noodle during microwave heating varied with diam. When a noodle with a diam. of 15 mm was heated, the temp. at the centre of the noodle reached 60degC in 1 min, while the surface temp. was 40degC. As a result, only starch granules in the centre of the noodle were gelatinized. Starch granules in the noodle were confirmed to be gelatinized using polarizing microscopy. In contrast, heating a noodle with of 7 mm diam. produced a rapid increase in temp. with microwave irradiation, and the difference in temp. between the centre and the surface was small. Though it was attempted to gelatinize only the centre of the noodles of 7 mm diam. by microwave, the entire cross-section of the noodle was gelatinized. In order to gelatinize only the centre of the 7 mm diam. noodle, the difference in dielectric characteristics of the microwave between ice and water was utilized. Only the surface of the noodle was frozen (the centre remained unfrozen), the sample was heated by microwave, and polarizing microscopy was used to confirm that the starch granules in the noodle were gelatinized while the surface molecules were not.