Abstract
To discuss the effect of addition of isolated soybean protein (ISP) on physical properties of starch noodle (Harusame), the noodles were made from potato, mung bean or broad bean starch mixed with ISP using pressure extruder, at 80°C unless otherwise mentioned. The extruded starch were heated in boiling water for 3min, washed with water, and dried immediately, or, frozen, thawed, drained and dried. The noodles were cooked in boiling water for 3min, washed and their transparency, swelling power, solubility and texture by tensipresser were measured for comparison and they were also subjected to organoleptic test. The results obtained were as follows.
1. The noodle from potato starch added by 5% ISP is transparent, higher tensile strength and elongation elastic modulus, less adhesiveness, being non-sticky, and lower solubility than the noodle from potato starch only. According to organoleptic test ISP was effective to make more acceptable, ranking next to noodles made in China.
2. By raising extrusion temperature from 80°C to 120°C the cooked noodle from potato starch only was extremely hard and sticky, being difficult to separate each other, however, the addition of ISP made the noodle more elastic and chewy, and, even in the case of ordinary drying, the noodles were not sticky and easy to separate each other.
3. Effect of freezing of noodle before drying on physical properties of cooked noodles were examined and the effects were evident in potato starch showing higher value in compression and tension test, and not in mung bean starch and mixture of potato and sweet potato starch (1:1). However by adding ISP physical properties of noodles from these starches were improved, being better than frozen noodles from potato starch.
