CONTRIBUTION OF THE CHEMICAL-STRUCTURE OF WHEAT-STARCH TO JAPANESE NOODLE QUALITY

Wheat starch has been completely digested with bacterial a-amylase, an d the pattern of oligosaccharides obtained from this digestion varies with starches from different wheat varieties. Wheat varieties of good Japanese noodle-making quality (based on sensory testing) give relativ ely small amounts of oligosaccharides with a degree of polymerisation (DP) of 5 or greater, while varieties of poor noodle-making quality gi ve much greater amounts of these larger oligosaccharides. There is a s ignificant negative correlation between the amount of DP5 oligosacchar ide and noodle eating quality. The correlation between the amount of t his oligosaccharide and starch paste viscosity was much smaller. The s ize of the HPLC peak corresponding to this oligosaccharide may be used as a rapid method of screening for noodle-making quality. Because oli gosaccharides of greater than DP4 should have at least one branch poin t, the results suggest that the structure of the amylopectin in starch of good noodle-making wheats has relatively few branch points close t ogether. Amylose also appeared to be important for noodle quality. The optimum amylose content seemed to be about 22% for good quality noodl es, with starch of higher or lower amylose content coming from flour o f lower noodle-making quality. Factors other than amylose content must contribute to noodle quality, as some flours of relatively poor noodl e quality also contained close to the optimum amount of amylose.