title: Changes in sugars, acids, and volatiles during ripening of koubo [Cereus peruvianus (L.) Miller] fruits.
abstract: The columnar cactus Cereus peruvianus (L.) Miller, Cactaceae (koubo), is grown commercially in Israel. The unripe fruits are green, and the color changes to violet and then to red when the fruit is fully ripe. The content of soluble sugars was found to increase 5-fold during ripening. Glucose and fructose were the main sugars accumulated in the fruit pulp, and each increased from 0.5 to 5.5 g/100 g fresh weight during ripening. The polysaccharides content decreased during ripening from 1.4 to 0.4 g/100 g fresh weight. The titratable acidity decreased and the pH increased during ripening. The major organic acid found in the fruit was malic acid, which decreased from 0.75 g/100 g fresh weight at the mature green stage to 0.355 g/100 g fresh weight in ripe fruits. Citric, succinic, and oxalic acids were found in concentrations lower than 0.07 g/100 g fresh weight. Prominent accumulation of aroma volatiles occurred toward the end of the ripening process. The main volatile found in the ripe fruit was linalool, reaching concentrations of 1.5-3.5 microg/g fresh weight.
authors.affiliation: Department of Life Sciences and Institutes for Applied Research, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105, Israel.
authors.forename: Racheli
authors.initials: R
authors.lastname: Ninio
authors.forename: Efraim
authors.initials: E
authors.lastname: Lewinsohn
authors.forename: Yosef
authors.initials: Y
authors.lastname: Mizrahi
authors.forename: Yaron
authors.initials: Y
authors.lastname: Sitrit
mesh_terms: D000143:Acids / Q000032:analysis*; D029421:Cactaceae / Q000737:chemistry / Q000254:growth & development*; D002241:Carbohydrates / Q000032:analysis*; D003116:Color; D005638:Fruit / Q000737:chemistry* / Q000254:growth & development*; D006863:Hydrogen-Ion Concentration; D009812:Odorants / Q000032:analysis*; D011134:Polysaccharides / Q000032:analysis; D012995:Solubility; D014835:Volatilization
chemical_list: D000143:Acids; D002241:Carbohydrates; D011134:Polysaccharides