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Determination of Damaged Starch and Diastatic Activity in Wheat Flour Using a Flow-Injection Analysis Biosensor Method

¹Technical Research Laboratories, Nisshin Flour Milling Co., Ltd., 5-3-1 Tsurugaoka, Oimachi, Iruma-gun, Saitama 356, Japan. ²Cereal Research Laboratory, Nisshin Flour Milling Co., Ltd., 5-3-1 Tsurugaoka, Oimachi, Iruma-gun, Saitama 356, Japan. ³Japan Advanced Institute of Science and Technology in Ishikawa, 15 Asahidai, Tatsukuchi-machi, Nomi-gun, Ishikawa 923-12, Japan. ⁴Faculty of Information Science, Hiroshima City University, 151-5 Ozuka, Numata-cho, Asaminami-ku, Hiroshima 731-13, Japan. ⁵Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153, Japan. ⁶Corresponding author. E-mail: karube@bio.rcast.u-tokyo.ac.jp

The determination of damaged starch and diastatic activity in flour was studied using a flow-injection analysis (FIA) biosensor system. The system consisted of an oxygen electrode and an immobilized enzyme column containing purified glucoamylase and glucose oxidase immobilized on activated aminopropyl glass beads. The biosensor system has an optimum pH between 6.5 and 7.5 and an optimum temperature of 35°C for glucose measurement. The response of the FIA biosensor was linear up to 1.000 g/L of glucose with a lower detection limit of 0.025 g/L. Each assay took about 20 min, and the system showed good reproducibility (r = 0.998, n = 8). When applied to the measurement of damaged starch and diastatic activity in wheat flour, the results obtained agreed with those obtained using the conventional methods of measurement. This biosensor system is a rapid practical alternative for the measurement of damaged starch and diastatic activity in wheat flour.