title: Thermal inactivation kinetics and application of phospho- and galactolipid-degrading enzymes for evaluation of quality changes in frozen vegetables.
abstract: Lipid-acyl hydrolases (LAHases) play significant roles in lipid degradation during the storage of vegetables. In particular, spinach contains a large portion of galactolipids (59.5%) and phospholipids (22.4%) among its fat-soluble components, which are used as substrates for LAHases. Thermal inactivation of various LAHases, including phospholipases A, C, and D, phosphatase, and galactolipase, from spinach and carrot was investigated to optimize the blanching process prior to the frozen storage of vegetables. Thermostability of phospholipase C or galactolipase was greatest among the LAHases from both spinach and carrot. Galactolipase from spinach exhibited a D value of 3.39 x 10(2) s at 80 degrees C and a z value of 8.21 degrees C, whereas phospholipase C from spinach showed D(80) of 1.72 x 10(2) s with a z value of 9.26 degrees C. In the case of LAHases from carrot, the D(65) and z values of galactolipase were 6.66 x 10(2) s and 8.69 degrees C, respectively, whereas phospholipase C displayed D(85) of 3.12 x 10(2) s and a z value of 15.8 degrees C. Highly active and thermostable galactolipase and phospholipase C in spinach and carrot made it possible for them to be used as indicator enzymes for the determination of quality deterioration of the stored vegetables.
authors.affiliation: Department of Food Science and Technology and Research Center for New Bio-Materials in Agriculture, School of Agricultural Biotechnology, Seoul National University, Suwon 441-744, South Korea.
authors.forename: M J
authors.initials: MJ
authors.lastname: Kim
authors.forename: J M
authors.initials: JM
authors.lastname: Oh
authors.forename: S H
authors.initials: SH
authors.lastname: Cheon
authors.forename: T K
authors.initials: TK
authors.lastname: Cheong
authors.forename: S H
authors.initials: SH
authors.lastname: Lee
authors.forename: E O
authors.initials: EO
authors.lastname: Choi
authors.forename: H G
authors.initials: HG
authors.lastname: Lee
authors.forename: C S
authors.initials: CS
authors.lastname: Park
authors.forename: K H
authors.initials: KH
authors.lastname: Park
mesh_terms: D005511:Food Handling; D038983:Galactolipids; D006017:Glycolipids / Q000378:metabolism*; D006358:Hot Temperature; D006867:Hydrolases / Q000378:metabolism*; D007700:Kinetics; D010743:Phospholipids / Q000378:metabolism*; D013379:Substrate Specificity; D014675:Vegetables / Q000201:enzymology*
chemical_list: D038983:Galactolipids; D006017:Glycolipids; D010743:Phospholipids; D006867:Hydrolases