| Wheat starch was isolated in >90% recovery from wheat flour by protease digestion in the absence of alpha-amylase. The inner and outer zones of cooked commercial salt noodles (1 x 3 mm) were separated manually, and their moisture levels determined to be 65 and 85%, respectively. The average noodle moisture was 75%. Five wheat starches were isolated from two Australian and three USA wheat flours; their swelling powers at 92.5°C (1.67% solids) varied from 15.2 to 22.6 g/g. Those wheat starches at concentrations of 10%, 25% and 35% in water were heated to 62--65°C with gentle stirring to form a thick paste. A paste was transferred to the pre-warmed concentric cylinder cell of a dynamic rheometer, and the mixture was heated in the rheometer from 65 to 95°C at 2°C/min, cooled from 95 to 25°C at 1°C/min, then held at 25°C for 12 hr. At low concentration (10%), the high swelling starches, typical of those in good-quality, Japanese, salt noodle flours such as from the Australian wheat Eradu, gave gels (low tan delta) at 25°C with a storage modulus (G') higher than the low swelling starches. However, at high concentration (25% and 35%) the reverse was true. Adding one part of hydroxypropylated wheat starch and one part potato starch to 8 parts of a low-swelling hard-winter wheat flour (14.3% protein, d.b.) gave a gel with almost the same G' and tan delta values as Eradu flour (10.9% protein, d.b.), and also Ike flour (14.3% protein, d.b.). Ike is a USA hard red wheat that contains high swelling starch. Triangular taste tests on cooked noodles indicated that a low swelling hard wheat flour, which is the most common type, could be used to produce high quality salt noodles having a texture equal to noodles from a high swelling wheat flour if the hard wheat flour was blended with 20% of a 1:1 (w/w) mixture of potato starch and a high swelling modified wheat or potato starch. |
