Antioxidant Activity of Phenolic Compounds in Bulk Camellia Oil and Corresponding Oil in Water (O/W) Emulsions

Yong Zhu,Paul D Prenzler,Hai-Yan Zhong,Qi-Zhi Long,Bo Zhou

doi:10.19026/ajfst.5.3089

Abstract

The antioxidant activities of gallic acid, propyl gallate, (+)-catechin and quercetin in bulk camellia oil and corresponding emulsions were investigated using hydroperoxides and nonanal as indicators of oxidation. In bulk oil, these phenolic compounds showed antioxidant activities with the order of gallic acid>quercetin>propyl gallate> (+)- catechin when measured using hydroperoxides and gallic acid>quercetin>(+)-catechin>propyl gallate using nonanal. In emulsions, propyl gallate and (+)-catechin showed antioxidant activities for the entire duration of the experiment, while quercetin and gallic acid displayed antioxidant activities for 10 days, and then pro-oxidant activities thereafter. Results suggested that in bulk oil, the antioxidant activity was regulated by phenol polarity and hydrogen atom donating ability too. In emulsions, the antioxidant activity of phenolic compounds seems to be related to their affinity toward the emulsifing agent rather than their polarity.

Highlights

Camellia oil (Camellia oleifera) is one of the four major tree-bearing oils with health benefits, since it has abundant antioxidants, such as tocopherols, polyphenols etc
The interfacial particle size of droplet and type of emulsifier (cationic, anionic, and Emulsification was carried out using a sonicator (Model W-10, Inc., and New York). 2.4 μmol of gallic acid, propyl gallate, (+)-catechin and quercetin was added into 40 mL emulsion, respectively
Neutral) may affect the oxidative stability of emulsions. These additional factors are being considered in response to studies showing nonlinear relationships between polarity and antioxidant activities in emulsions (Laguerre et al, 2010; Shahidi and Zhong, 2011) and some phenolic compounds acting as pro-oxidants in emulsions (Huang and Frankel, 1997; Mattia et al, 2009)

Summary

Introduction

Camellia oil (Camellia oleifera) is one of the four major tree-bearing oils (palm, olive and coconut oils) with health benefits, since it has abundant antioxidants, such as tocopherols, polyphenols etc. 2.4 μmol of gallic acid, propyl gallate, (+)-catechin and quercetin was added into 40 mL emulsion, respectively. These additional factors are being considered in response to studies showing nonlinear relationships between polarity and antioxidant activities in emulsions (Laguerre et al, 2010; Shahidi and Zhong, 2011) and some phenolic compounds acting as pro-oxidants in emulsions (Huang and Frankel, 1997; Mattia et al, 2009).

Results

Conclusion