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Changes in wall-bound phenolic acids, phenylalanine and tyrosine ammonia-lyases, and peroxidases in developing durum wheat grains (Triticum turgidum L. var. Durum)

Regnier, T., Macheix, J.J.
Journal of agricultural and food chemistry 1996 v.44 no.7 pp. 1727-1730
Triticum turgidum, cultivars, ripening, developmental stages, chemical composition, phenolic acids, tyrosine, ammonia-lyases, phenylalanine ammonia-lyase, peroxidase
Some aspects of phenolic metabolism have been followed during the development of durum wheat grain. Bound ferulic (FA) and p-coumaric (PCA) acids have been extracted after alkaline hydrolysis and quantified by high-performance liquid chromatography. They increased to reach a maximum during the hydrical step and then decreased rapidly during grain dehydratation. Changes in phenylalanine ammonia-lyase (PAL) (E.C. and L-tyrosine ammonia-lyase (TAL) (E.C. activities have been monitored all along the development of the grain. TAL activity was maximal 2 days before PAL, at the beginning of the hydrical step. The presence of a maximal peroxidasic activity at the end of the hydrical step should be linked to the decrease of alkaline-resistant bound forms of FA. These results may suggest a possible role of peroxidase in the progressive changes from ester-linked forms of phenolic acids to insoluble derivatives, resistant to alkaline hydrolysis.