SCREENING LEGUME FORAGES FOR SOLUBLE PHENOLS, POLYPHENOL OXIDASE AND EXTRACT BROWNING

Red clover (Trifolium pratense) is a legume that will brown quickly up on harvesting. This browning of red clover has been correlated to a re duction in proteolysis and requires the presence of a polyphenol oxida se and soluble phenol substrates. A method was developed to screen for ages for soluble phenols, soluble polyphenol oxidase activity and extr act browning. Fourteen different legumes and 24 red clovers (22 plant introductions and two cultivars), field grown in replicated plots, wer e screened. Of the different legumes, only red clover had measurable s oluble polyphenol oxidase activity (7.70 abs g(-1) leaf) and underwent browning (0.245 abs g(-1) leaf). This extract browning and polyphenol oxidase activity were present in all red clovers tested and ranged fr om 0.153 to 0.458 and 6.00 to 9.00 abs g(-1) leaf, respectively. All o f the legumes, including all red clovers, gave a positive response for soluble phenols.