Inactivation kinetics of purified tomato polygalacturonase by thermal and high-pressure processing.
Tomato polygalacturonase (PG) was extracted from ripe tomatoes and purified by cation exchange and gel filtration chromatography. Cation exchange chromatography yielded two peaks with PG activity: the first peak was identified as PG2 (the heat labile form) and the second one as PG1 (the heat stable form). Both PG2 and PG1 presented a molar mass of 42 kDa when analyzed by SDS-PAGE and an isoelectric point >9.3. Thermal inactivation of purified tomato PG2, at pH 4.4, in the temperature range from 53 to 63 degrees C, followed first-order kinetics. Combined pressure-temperature inactivation of tomato PG2 was studied at 5-55 degrees C/100-600MPa. Under all pressure-temperature conditions, PG2 inactivation followed first-order kinetics. Purified tomato PG1, although more thermostable than PG2, showed a pressure stability very similar to that of PG2. These results indicate that high-pressure processing is an efficient alternative to inactivate tomato PG without the need for applying high temperatures.
Fachin
Diana
D
Laboratory of Food Technology, Department of Food and Microbial Technology, Faculty of Agricultural and Applied Biological Sciences, Katholieke Universiteit Leuven, Kasteelpark Arenberg 22, B-3001 Leuven, Belgium.
Smout
Chantal
C
Verlent
Isabel
I
Ly Nguyen
Binh
B
Van Loey
Ann M
AM
Hendrickx
Marc E
ME
D004789:Enzyme Activation; D004795:Enzyme Stability; D005511:Food Handling / Q000379:methods*; D006358:Hot Temperature; D007700:Kinetics; D018551:Solanum lycopersicum / Q000201:enzymology*; D011096:Polygalacturonase / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D011312:Pressure
D011096:Polygalacturonase