葡萄柚果實的色澤

The Color of Grapefruits

葡萄柚有白、粉紅、紅色至深紅色的品種。現有的栽培品種大多是由白色品種'Duncan'經芽條陸續變異而來，屬周緣嵌合體。葡萄柚果實主要的色素成分是類胡蘿蔔素，表現粉紅色至深紅色的是茄紅素與β-胡蘿蔔素。白肉品種則無該兩成分或含量甚低。紅色系品種間顏色之深淺，主要受茄紅素含量的影響，隨著果實的發育，色澤逐漸加深，之後又漸褪色。葡萄柚果皮及果肉的顏色可受砧木、生育時期、氣候環境條件及植株年齡的影響。現有栽培管理作業中，影響葡萄柚果皮色澤最大者是套黑色紙袋。紅色系品種在果實發育初期套袋，果皮由綠色逐漸轉為橙黃，至採收時，套袋者果皮已轉為橙紅色。 Grapefruit can be grouped into white, pink, red and deep red varieties according to flesh color. Most of them arised directly or indirectly from the white variety 'Duncan' by periclinal chimera. Lycopene with a lesser extent of β-carotene are the major pigments in pink and red varieties, while those carotenoids are not found or very low in content in white ones. There is a significant correlation between red color index and lycopene content in flesh and juice of red varieties. The coloration of red grapefruits can be affected by the growing season, variety, rootstock/interstock, tree age, fruit size and climate. Covering red grapefruits with black paper bags in early growing stage altered the peel color from yellow to reddish at harvest.