Cereal Chem. 73 (1):88-95 |
Reduced Browning in Raw Oriental Noodles by Heat and Moisture Treatment of Wheat (1).
Keswara Rao Vadlamani (2) and Paul A. Seib (2). (1) Contribution 95-522-J from the Kansas Agricultural Experiment Station, Manhattan, KS 66502. (2) Graduate research assistant and professor, respectively, Department of Grain Science and Industry, Kansas State University, Manhattan, KS 66506. Accepted October 31, 1995. Copyright 1996 by the American Association of Cereal Chemists, Inc.
Flours milled from heat- and moisture-treated hard white wheat (KS-196) contained reduced levels of polyphenol oxidase (PPO), but not peroxidase (PO). With a 12-min heating period, the PPO activity decreased with increasing moisture content (MC) from 13 to 15%, whereas with 4- and 8-min heating periods, the PPO activity was insensitive to moisture level. When the tempering period was increased from 1 to 4 hr at 19% MC, PPO activity in the heat-treated wheat was unaffected. Three other wheat cultivars, tempered to 15% MC for 1 hr and then heat-treated for 8 min at 100°C, yielded flours with approximately 50% reduction in PPO activity. Heating the KS-196 wheat for 12 min at 100°C reduced PPO activity in flour by as much as 76%, but destroyed the elasticity of gluten as determined by mixograms. White noodles and yellow alkaline noodles, made from heat-treated (15% MC, 8 min, 100°C) KS-196 wheat, had improved brightness in the raw state and showed little change in cooking quality and cooked texture, except for reduced firmness. When KS-196 wheat was pearled to remove 28% of its weight, and the pearled kernels were heat- and moisture-treated at 15% MC for 8 min at 100°C, the straight-grade flour contained 75% less PPO activity than the untreated wheat flour. White noodles made from pearled, heat- and moisture-treated wheat were brighter than those made from pearled untreated wheat. A white noodle dough, made from heat- and moisture-treated wheat with aminoguanidine bicarbonate added, had the brightest dough (L* = 75) after 24 hr at 25°C.