title: The role of hydrolases in the loss of firmness and of the changes in sugar content during the post-harvest maturation of Carica papaya L. var solo 8.
abstract: Fruit ripening is associated with many hydrolase activities involved in the softening of the fruit during the maturation. This study investigates the relationship between the loss of firmness along with the changes of sugar content and the enzymatic activities in Carica papaya L.var solo 8 during post-harvest storage. Three maturation stages (green immature: the fruit is entirely green, green mature: the fruit shows 1/32 yellow skin and fully mature: the fruit shows 1/8 yellow skin) have been selected and stored at 15, 22 and 28 °C. The reduction of fruit firmness, total sugar contents, refractive index (% Brix) and enzymatic activities were measured. Low enzymatic activities (0.035 μmol/min/mg) were recorded in fruit harvested at the green immature stage with no significant (p ≥ 0.05) effect on the softening while fruit harvested at the green mature and fully mature stages showed enzymatic activities 7 times as high as those of the green immature stage. These high enzymatic activities were responsible for the loss of firmness of the fruit. Accordingly, papayas at the green mature and fully mature stages displayed higher maxima of sugar content (4.8 g/100 g at 28 °C at day 12, and 10.2 g/100 g at 22 °C at day 8, respectively) at higher temperatures. Meanwhile in green immature papayas, the maximum was only 4.3 g/100 g at 22 °C and day 12 of storage. The results show that the loss of firmness of the papaya was highly related to the hydrolytic enzyme activities and the sweet taste to the presence of simple sugars such as galactose liberated from the polysaccharide complexes.
authors.affiliation: Laboratory of Food Biochemistry and Tropical Products Technology, Department of Food Science and Technology, Abobo-Adjamé University, Abidjan, 02 B.P. 801, Côte d'Ivoire.
authors.forename: Benjamin N
authors.initials: BN
authors.lastname: Yao
authors.affiliation: Laboratory of Food Biochemistry and Tropical Products Technology, Department of Food Science and Technology, Abobo-Adjamé University, Abidjan, 02 B.P. 801, Côte d'Ivoire.
authors.forename: Kablan
authors.initials: K
authors.lastname: Tano
authors.affiliation: Laboratory of Biochemistry and Food Technology, Abobo-Adjamé University, Abidjan, 02 BP 801 Côte d'Ivoire.
authors.forename: Hubert K
authors.initials: HK
authors.lastname: Konan
authors.affiliation: Laboratory of Food Biochemistry and Tropical Products Technology, Department of Food Science and Technology, Abobo-Adjamé University, Abidjan, 02 B.P. 801, Côte d'Ivoire.
authors.forename: Gerard K
authors.initials: GK
authors.lastname: Bédié
authors.affiliation: Faculty of Sciences, University College of Saint-Boniface, 200 Avenue de la Cathédrale, Winnipeg, Manitoba Canada R2H 0H7.
authors.forename: Mathias K
authors.initials: MK
authors.lastname: Oulé
authors.affiliation: Laboratory of biotechnology and Food Microbiology, Department of Food Science and Technology, University of Abobo-Adjamé, 02 BP 801 Abidjan 02, Côte d'Ivoire.
authors.forename: Rose
authors.initials: R
authors.lastname: Koffi-Nevry
authors.affiliation: Department of Food Science and Nutrition and Horticulture Research Center, Laval University, Sainte-Foy, Quebec Canada G1K 7P4.
authors.forename: Joseph
authors.initials: J
authors.lastname: Arul
keywords: Firmness; Hydrolases; Maturation; Papaya; Post-harvest; Sugar content