KMID : 1007519990080060361
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Food Science and Biotechnology 1999 Volume.8 No. 6 p.361 ~ p.366
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Relationship of Wheat Polyphenol Oxidase Activity of Color of Asian Raw Noodles
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Kim, Sung Hoon
Kim, Mi Jung/LEE, Won Jong/Shelton, David R.
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Abstract
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Polyphenol oxidase (PPO) has been implicated in darkening reactions that limit the acceptability of wheat-based end products, such as Asian noodles. A simple, rapid procedure was developed for determining activity of PPO in wheats without for seed grinding. This method may assist wheat breeders in making decisions about advancing experimental lines. Seeds (0.4 g) were crushed with a plier, and a freshly prepared L-DOPA solution was added. The mixture was incubated for 5 min at 37¡É and filtered through a syringe filter (25 mm cellulose acetate, pore size 0.2 micrometer). Absorbance of the reaction solution was measured at 475 nm. The method correlated well (r = 0.86, p<0.0001) with PPO assay performed on ground grain suspensions. Twenty five samples consisting of four hard red winter wheat and one hard white wheat were harvested in 1998 at five locations in Wyoming. PPO activity in wheat samples was affected by both variety and growing location. The activity was significantly influenced by the interaction of variety and location effects. PPO activity correlated well with the rate of decrease in brightness (L^*) of 25 raw Asian noodle sheets at 4 hr of storage (r = 0.75, p<0.0001) and increase in yellowness (b^*) after 24 hr of storage at 21¡É (r = 0.69, p<0.0001).
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