Hiroshi Koaze

Postharvest ripening and ethylene biosynthesis in purple passion fruit

Abstract A study was undertaken to investigate the pattern of changes in some chemical constituents, ethylene biosynthesis, and the effect of ethylene treatment during postharvest ripening in purple passion fruit (Passiflora edulis Sims.). During ripening, sucrose content decreased while fructose and glucose contents increased. Citric and malic acid contents slightly increased during the early stage of ripening and decreased thereafter. Amino acids did not change significantly, except for proline, which increased rapidly towards the late stage of ripening. While 1-aminocyclopropane-1-carboxylic acid (ACC) content and ACC synthase activity increased in parallel with ethylene production, ACC oxidase activity was already high when harvested at the turning stage and further increased during ripening. Application of 1000 ppm ethylene for 24 h did not induce earlier onset of ethylene production when applied on harvest day, but was effective when applied one day or five days after harvest. The results indicate that purple passion fruit produces ethylene with the same biosynthetic pathway as other tissues in higher plants; its ethylene biosynthesis is regulated mainly by ACC synthase activity, and the sensitivity to ethylene might have changed after harvest as the fruit ripened.

Analytical Discrimination of the Cold-Pressed Oils of Mandarins and their Hybrids

Abstract Volatile compositions of the cold-pressed peel oils of a Satsuma mandarin cultivar, from Japan, and four other cultivars of mandarin hybrids such as Temple, Orlando, Kara and Minneola obtained from Ethiopia and Kenya were analyzed by capillary GC and GC/MS, without prior separation. Satsuma mandarin and Temple were characterized by high concentrations of (E,E)-α-farnesene and linalool, respectively. The enantiomeric distribution of α-pinene, β-pinene, sabinene, limonene, linalool, citronellal and α-terpineol was studied by simple and reliable enantioselective GC methods involving either a chiral capillary column or an on-line coupling of non-chiral and chiral capillary columns. The (+)-enantiomers of most of the components in all of the analyzed oils were present in excess, except for linalool and citronellal in the oils of Satsuma mandarin and Temple, respectively. Cold-pressed oils of Satsuma mandarin were found to contain about 75% enantiomeric excess of (3R)-(-)-linalool instead of (3S)-(+)-linalool excess, as was found in the oils of other mandarin cultivars and hybrids.