title: Effect of temperature on soluble invertase activity, and glucose, fructose and sucrose status of onion bulbs (Allium cepa) in store.
abstract: The activity of soluble invertase, and the variation in glucose, fructose and sucrose contents in onion bulbs (Allium cepa) during long-term storage at 10 degrees C and 20 degrees C were investigated. Invertase activity increased progressively after 8 weeks to 0.084 and 0.092 nkat/g fresh weight (FW), then sharply to 0.29 and 0.35 nkat/g FW at 20 degrees C and 10 degrees C, respectively, and remained high during 5 weeks. Then, activity decreased abruptly to 0.039 and 0.041 nkat/g, and remained low during the last 8 weeks and close to that observed initially. Glucose increased to 17.73 and 14.62 mg/g FW after 4 weeks at 20 degrees C and 10 degrees C, respectively, then decreased sharply between week 5 and week 7 to 4.13 and 4.91 mg/g FW, respectively, and remained rather stable ranging from 9 and 10 mg/g FW at both temperatures. Fructose showed a similar pattern and was 14.8 and 21.68 mg/g FW at 20 degrees C and 10 degrees C, respectively. Between week 10 and week 24, fructose ranged from 5 and 6 mg/g FW, and from 6 and 7 mg/g FW at 20 degrees C and 10 degrees C, respectively. Sucrose increased to 19.63 and 14.43 mg/g FW at 20 degrees C and 10 degrees C, respectively, decreased during 3 weeks, and then increased randomly from 5.69 to 9.42 mg/g FW at 20 degrees C, but remained in a steady state at 10 degrees C ranging 5.03 +/- 0.78 mg/g FW. During the last 6 weeks, the sucrose content was higher at 20 degrees C than at 10 degrees C. The fructose-glucose ratio varied during the first 8 weeks but remained at a steady level during the last 16 weeks. The (glucose+fructose)/sucrose ratio increased randomly at 10 degrees C, whereas at 20 degrees C the ratio increased during 10 weeks then decreased progressively during the final 14 weeks.
authors.affiliation: Department of Food and Nutrtion Sciences, Rakuno Gakuen University, Ebetsu, Hokkaido, Japan. ben-nour@rakuno.ac.jp
authors.forename: Noureddine
authors.initials: N
authors.lastname: Benkeblia
authors.forename: Shuichi
authors.initials: S
authors.lastname: Onodera
authors.forename: Taiki
authors.initials: T
authors.lastname: Yoshihira
authors.forename: Shinichi
authors.initials: S
authors.lastname: Kosaka
authors.forename: Norio
authors.initials: N
authors.lastname: Shiomi
mesh_terms: D005504:Food Analysis / Q000379:methods; D005519:Food Preservation; D005632:Fructose / Q000032:analysis; D005947:Glucose / Q000032:analysis; D009753:Nutritive Value; D019697:Onions / Q000737:chemistry*; D013395:Sucrose / Q000032:analysis; D013696:Temperature; D043324:beta-Fructofuranosidase / Q000032:analysis*
chemical_list: D005632:Fructose; D013395:Sucrose; D043324:beta-Fructofuranosidase; D005947:Glucose