Cereal Chem. 73 (4):452-456 |
Analytical Techniques and Instrumentation
New Viscograph for Rheological Analysis of a Small Quantity of Wheat Flour.
Kazutaka Uno (1,2), Toru Imai (3), Nobuo Ogata (4), and Kaoru Kohyama (3). (1) Kyowa Hakko Kogyo Co., Ltd., Tsukuba Laboratory, Miyukigaoka2, Tsukuba-shi, Ibaraki-pref., 305, Japan. (2) Corresponding author. Fax: 81-296-56-4288. (3) National Food Research Institute Kannondai2-1-2, Tsukuba-shi, Ibaraki pref., 305, Japan. (4) Kyowa Hakko Kogyo Co., Ltd., Food & Liquor Laboratory, Ami 4041, Ami-cho, Inashiki-gun, Ibaraki pref., 305, Japan. Accepted April 22, 1996. Copyright 1996 by the American Association of Cereal Chemists, Inc.
A cone-plate viscometer was developed to analyze viscosity changes during heating of a small quantity of wheat flour suspension. The instrument consists of a cone, a plate, a temperature-control heater, and a water trap to prevent water evaporation from a sample. With this apparatus it is possible to record a viscogram using only approximately 100 mg of wheat flour. Although the flour concentration was low, the temperature at which the viscosity began to rise in this cone-plate viscometer was closer to the gelatinization temperature determined by differential scanning calorimetry than that determined with other viscographs. It suggests that the new apparatus was more sensitive to initial swelling of gelatinized starch. The maximum viscosity in viscograms of wheat starch measured by the new instrument decreased with the alpha-amylase activity. Depending on the heating rate, viscogram parameters obtained with this instrument were well correlated with those obtained with other viscometers.