67B-8 |
|
T. M. RABABAH, N. S. Hettiarachchy, and R. Horax. Dept. of Food Science, Univ. of Arkansas, 2650 N. Young Ave., Fayetteville, AR 72701 Due to toxicological concern of synthetic antioxidants, there is an increasing demand in natural antioxidants and plant extracts to inhibit lipid oxidation and off-flavor development in lipid-based food products. Plant extracts have the potential as natural antioxidants due to their phenolic constituents. The objectives include: 1) Preparation and evaluation of selected plant extracts for total phenolics (TP) and antioxidant activities (AA), 2) Evaluation of selected hydrolyzed extracts for AA, and 3) Evaluation of promising extracts for synergistic activity. The TP and AA of green tea (GT), black tea, fenugreek, grape seed (GS), gotu kola, rosemary, ginger, and ginko extracts were determined by Folin-Ciocalteu method, and conjugated diene measurement of methyl linoleate (MeLo) model system, respectively. AA of GT/ GS extracts/ combinations were determined using an oxidative stability instrument (OSI) on chicken fat system. Vitamin E and TBHQ were included for comparison. Hydrolyzed GT/ GS extracts/ combinations were evaluated for synergistic antioxidant activity. The TP content of the plant extracts ranged from 24.8 - 92.5 mg of chlorogenic acid equivalent /g dry material. The AA of the plant extracts determined by conjugated diene measurement of MeLo ranged from 3.4-86.3%. The non-hydrolyzed and hydrolyzed GT extracts had similar AA, ranging from 41.0-88.8% and 45.9 - 88.2%, respectively. AA of combined non-hydrolyzed extracts were higher than those of hydrolyzed extracts (41-91.7% and 34.3-88.2%, respectively). AA determined by OSI followed a similar trend to conjugated diene measurement, and ranged from 4.6 -10.2 h, but higher than that of control (2.3 h) (Induction time). TP contents differed among plant extracts. The type of phenolics contributed to AA. MeLo and OSI systems can be effectively used to determine AA in model and food systems. GT and GS extracts can be used to retard lipid oxidation in a variety of food products.
Session 67B, Food Chemistry: Antioxidants and bioactive agents
|