Flour Particle Size, Starch Damage, and Alkali Reagent: Impact on Uniaxial Stress Relaxation Parameters of Yellow Alkaline Noodles

Three patent flours, each possessing three different levels of starch damage were prepared from a single hard white spring wheat. Each flour was sieved to yield three flours with different particle size distributions (85-110, 110-132, 132-183 μm). Raw alkaline noodles were prepared from the nine flours using either 1% w/w kansui (sodium and potassium carbonates in 9:1 ratio) or 1% w/w sodium hydroxide. Uniaxial stress relaxation parameters percent stress relaxation (SR%), initial rate of relaxation (k1) and the extent of relaxation (k2) were measured on the raw noodles immediately after production (t = 0 min) and at 60 min. Raw noodles after resting for 60 min were optimally cooked and stress relaxation parameters were measured. Raw noodles at t = 0 min exhibited SR%, k1, and k2 that were significantly (P < 0.0001) influenced by both the degree of starch damage and the type of alkaline reagent used. Flour particle size only influenced SR% and k1 (P < 0.025) but had no impact on k2. In raw noodles aged for 60 min, both SR% and k2 were significantly influenced by alkaline reagent, particle size, and starch damage (P < 0.01) while k1 was only affected by the degree of starch damage (P < 0.0001). Cooked noodle SR parameters were all significantly (P < 0.0001) influenced by alkaline reagent, particle size, and the degree of starch damage. Cooked noodles prepared from starch with low damaged flours within any given particle size range, regardless of the type of alkali employed, yielded the most rheologically elastic-like (firmer) noodles. Two potential mechanisms by which the degree of starch damage influences noodle elastic like texture are discussed.