Soursop pectinesterases: thermostability and effect on cloud stability of soursop juice

• Main Authors: Misman, Siti Arbaisah, Ali, Asbi, Abdul Hamid, Junainah, Bakar, Jamilah, Kennedy, J. F.
• Format: Article
• Language: English; English
• Published: Elsevier 1997
• Online Access: http://psasir.upm.edu.my/id/eprint/36028/1/Soursop%20pectinesterases%20thermostability%20and%20effect%20on%20cloud%20stability%20of%20soursop%20juice.pdf; http://psasir.upm.edu.my/id/eprint/36028/7/1-s2.0-S0144861797000507-main.pdf; http://psasir.upm.edu.my/id/eprint/36028/; http://www.sciencedirect.com/science/article/pii/S0144861797000507

The thermostability of two forms of purified pectinesterase from soursop fruit were studied. The heat stability data showed that PE I is more heat stable than PE II at pH 7.5. The D and Z values were evaluated in the range 45–75°C. The D values at 65°C were approximately 5.8 min and 3.3 min for PE I and PE II respectively. The changes in temperature required to increase the inactivation rate tenfold (Z value) were calculated at 8.5 and 8.6°C for PE I, PE II respectively. Both enzymes also tested positive for their ability to destabilise soursop juice cloud at 5 and 30°C. Cloud destabilisation by PE I occurred the fastest (large decrease in A 660 nm) in the natural juice at 30°C.