Physiological and chemical studies of chilling injury in pepper fruits

Abstract

1. The present experiments show the identification and the changes of content of lignin, which is considered to be closely related to the hardness of plant tissue in pepper fruits. And the relation to the accumulation of phenolic substances in pepper seeds by low temperature storage reported in previous paper is discussed.2. The lignin in the peels and seeds of pepper fruits was isolated as lignin aldehydes by the method of alkaline nitrobenzene oxidation described by Stone and Blundell. The quantitative determination of the aldehydes was carried out using paper chromatography.3. The lignin aldehydes were detected by spraying on paper with 2% 2•4-dinitrophenylhydrazine in 2N HCl. Three spots were found as lignin aldehydes of peels and seeds. One spot was identified as vanillin by the determination of maximum absorption, Rf value, and color reaction of hydrazone while the other spots were unidentified substances.4. The vanillin content of pepper peels was fairly lower than that of seeds. At 6°C, the vanillin content of peels decreased by half of initial value 2 days after and then increased rapidly during subsequent storage period. The content in 20°C-stored fruits, on the contrary, increased gradually during 2 days of storage. The vanillin content in pepper seeds showed 685μg/g fresh weight before storage, and in the storage at 6°C it decreased rapidly to 417μg/g fresh weight after 2 days, and then increased to reach to a maximum of 807μg/g fresh weight after 7 days and the high level followed constantly during storage periods, while the content of that stored at 20°C increased gradually and reached a maximum after 7 days.