Polyphenol oxidase activities in wheat (Triticum Aestivum L.) grain

Wheat (triticum spp.) is one of the most popular cereals used in the world. an important problem for the flour and flour related products is their darkening and discoloration which is believed to result from polyphenol oxidase (ppo) activities. pakistani wheat grain collection from narc gene bank and some other cultivars were investigated for their ppo activities for the first time. different ppo substrates were employed which included caffeic acid,catechol,tyrosine,ldopa and phenol. among these substrates,l-dopa at ph 6.5 produced the highest enzyme activity. among the genotypes tested,chalsi showed the highest (150 units/min/g) sum of activities ppo activity while the minimum activity was exhibited by wafaq-2001 (34units/min/g). all the genotypes and the substrates tested,differed in a highly significant manner in variance analysis; and our results are also supported by correlation analysis. these results showed presence of genotypes both very high and very low in ppo activities and also supported the hypothesis that more than one ppo activities may be present in wheat grains.