A whole seed assay for polyphenol oxidase in Canadian Prairie Spring wheats and its usefulness as a measure of noodle darkening
Kruger, J.E.; Hatcher, D.W.; Depauw, R.
Cereal Chemistry 71(4): 324-326
ISSN/ISBN: 0009-0352 Accession: 008086123
A quantitative assay has been developed for assessing the polyphenol oxidase (PPO) levels in grain without the requirement for seed grinding. Seeds were steeped for 16 hr in water and then catechol substrate was added. The resulting color of the liquid was measured after 30 min using a kinetic microplate reader. The method correlated well (r = 0.85) for both the standard oxygen-electrode method for PPO assay performed on ground grain suspensions and the rate of decrease in brightness (L-*) or increase in yellowness (b-*) of a raw Cantonese noodle sheet after storage for 4 or 24 hr. A substantial amount of the enzyme is present in steep water and can also be used to assay for the relative PPO activity in the seed. The method should be particularly useful to plant breeders for screening of PPO levels in Canadian Prairie Spring wheats.