Chemical Changes during the Development and Ripening of the Fruit of Cucumis melo (Cv. Makdimon)

Abstract

Changes in the aroma volatiles, free amino acids, sugars, principal acids, and soluble minerals were studied during the development and ripening of the fruit of Cucumis melo L. Reticulatis group cv. Makdimon. Ethyl acetate was the most abundant volatile produced during the final growth stage, but ethanol was the major volatile found in immature fruit. Most of the free amino acids exhibited increases in concentration as the fruit underwent the ripening process. Sucrose, although absent in immature fruit, showed a dramatic increase during ripening to become the major carbohydrate constituent in the ripe fruit. The changes in total soluble solids during ripening showed close correlation with those found for pH, certain amino acids, and the elements sodium and potassium. Sucrose concentration has been shown to be an important fruit quality indicator, so these further correlations suggest that some of these parameters may be significant additional determinants of eating quality.

Flavour volatile production and regulation in fruit

“…Volatile compound concentration reached a maximum level at 43 d after anthesis, just before full slip (slip 0 separation) from the vine occurs with light pressure) (Wang et al 1996). Flavour volatile composition of the different melon types varies substantially, but appears to correlate with melon storage life.…”

“…Both fatty acid and amino acid biosynthesis are important to volatile formation in melons. The amino acids alanine, valine, leucine, and methionine increased during fruit ripening, in close association with volatile production and are believed to supply carbons for four groups of esters, ethyl acetate, 2-methylpropyl, 2-methylbutyl and thioether ester, respectively (Wyllie et al 1995;Wang et al 1996). When a comparison of amino acid content was made between the highly aromatic melon Makdimon and the low-aroma melon Alice, no significant difference in volatile concentration was found.…”

Functional Characterization of a Melon Alcohol Acyl-transferase Gene Family Involved in the Biosynthesis of Ester Volatiles. Identification of the Crucial Role of a Threonine Residue for Enzyme Activity*

“…Cell free extracts of 'Arava' were capable of acetylating a number of alcohols (1-butanol, 1-hexanol, 1-octanol, isoamyl alcohol, 1-octen-3-alcohol, benzyl alcohol, phenyl ethyl alcohol, and 3-methylthio-1-propanol), but it is probable that several AAT isoforms were present in the extract. On the other hand, Wang et al (1996) had shown that in another American cantaloupe genotype (Makdimon) the highest production of esters occurred during the latest stages of ripening.…”

Effect of Fruit Load on Partitioning of Dry Matter and Energy in Cantaloupe (Cucumis melo L.)

“…For each sample, determinations were replicated three times. Sulphur was not analysed as its concentration is very low in melon tissues (Wang, Wyllie and Leach, 1996). The mineral content was estimated by subtracting the fraction of organic material (carbonjhydrogenjoxygenjnitrogen) per unit dry mass from one.…”