Photobleaching, light-induced discolouration in red peppers
2006
Jung, J.W. | Lee, S.K.
Red peppers dried in sunlight experience surface bleaching, centred near the calyx, on the face exposed to the light. In this study, bleaching mechanisms were studied under simulated irradiation conditions by placing pericarp discs in 2-(N-morpholino) ethane sulfonic acid (MES) and sucrose solution. The moisture content near the calyx of the pepper decreased more slowly than that on the apex side. In addition, pericarp discs incubated without MES/sucrose solution retained more carotenoids than those incubated with solution after 27 h of light treatment. Carotenoids in pericarp discs exposed to the light decreased rapidly over the incubation time, whereas in the dark they decreased slowly and remained higher in content. Changes in malondialdehyde (MDA) level and electrolyte leakage were not observed for pericarp incubation in the dark. A sharp increase in the level of MDA and a change in electrolyte leakage from discs exposed to the light occurred when carotenoids were exhausted. Carotenoid degradation was markedly suppressed by the addition of ascorbic acid. These results demonstrate that carotenoids in red pepper pericarp played a role in protecting cells and were subsequently degraded under intense light conditions.
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