Thermal inactivation kinetics and application of phospho- and galactolipid-degrading enzymes for evaluation of quality changes in frozen vegetables

摘要

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 degreesC and a z value of 8.21 degreesC, whereas phospholipase C from spinach showed P-80 of 1.72 x 10(2) s with a z value of 9.26 degreesC. 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 degreesC, respectively, whereas phospholipase C displayed D-85 of 3.12 x 10(2) s and a z value of 15.8 degreesC. 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. [References: 25]