title: Changes of Major Antioxidant Compounds and Radical Scavenging Activity of Palm Oil and Rice Bran Oil during Deep-Frying.
abstract: Changes in antioxidant properties and degradation of bioactives in palm oil (PO) and rice bran oil (RBO) during deep-frying were investigated. The alpha (α)-tocopherol, gamma (γ)-tocotrienol and γ-oryzanol contents of the deep-fried oils were monitored using high performance liquid chromatography, and antioxidant activity was determined using 2-diphenyl-1-picryl hydrazyl (DPPH) radical scavenging activity. Results revealed that the antioxidant activity of PO decreased significantly (p < 0.05), while that of RBO was preserved after deep-frying of fries. As expected, the concentration of α-tocopherol in PO and γ-tocotrienol in both PO and RBO decreased significantly (p < 0.05) with increased frying. Results also showed that γ-tocotrienol was found to be more susceptible to degradation compared to that of α-tocopherol in both PO and RBO. Interestingly, no significant degradation of α-tocopherol was observed in RBO. It is suggested that the presence of γ-oryzanol and γ-tocotrienol in RBO may have a protective effect on α-tocopherol during deep-frying.
authors.affiliation: Department of Food Science, Faculty of Food Science and Technology, Universiti Putra Malaysia, UPM Serdang, Selangor 43400, Malaysia. azizahah@upm.edu.my.
authors.forename: Azizah Abdul
authors.initials: AA
authors.lastname: Hamid
authors.affiliation: Department of Food Science, Faculty of Food Science and Technology, Universiti Putra Malaysia, UPM Serdang, Selangor 43400, Malaysia. mpakdek@uoguelph.ca.
authors.forename: Mohd Sabri Pak
authors.initials: MS
authors.lastname: Dek
authors.affiliation: Department of Food Technology, Faculty of Food Science and Technology, Universiti Putra Malaysia, UPM Serdang, Selangor 43400, Malaysia. tancp@upm.edu.my.
authors.forename: Chin Ping
authors.initials: CP
authors.lastname: Tan
authors.affiliation: Department of Food Science, Faculty of Food Science and Technology, Universiti Putra Malaysia, UPM Serdang, Selangor 43400, Malaysia. asraf_zainudin@yahoo.com.
authors.forename: Mohd Asraf Mohd
authors.initials: MA
authors.lastname: Zainudin
authors.affiliation: Department of Food Science, Faculty of Food Science and Technology, Universiti Putra Malaysia, UPM Serdang, Selangor 43400, Malaysia. evelyn_kwf@hotmail.com.
authors.forename: Evelyn Koh Wee
authors.initials: EK
authors.lastname: Fang
keywords: deep-frying; free radical scavenging; kinetic degradation; oil antioxidants; vegetable oils