Evaluation of antioxidant activity of some plant extracts and their application to ground beef patties

The freeze-dried extracts from potato peels, fenugreek seeds and ginger rhizomes appeared to possess antioxidant activity against a beta-carotene-linoleic acid emulsion. Ginger rhizome extract exhibited the highest antioxidant activity and had an activity comparable to commercial antioxidants, sustane 20 and sustane HW-4. The antioxidant activity of freeze-dried extracts from ginger rhizomes and fenugreek seeds was maximum at pH 7.0, while for potato peel extract, it was maximum at pH ranging from 5.0 to 6.0. Potato peel and fenugreek seed extracts were more heat-stable than ginger rhizomes extract. The antioxidant activity was not affected by storage in dark conditions at similar to 5, similar to 25 and 37 degrees C over a period of 21 days, while a significant reduction was observed for extracts kept in light conditions at room temperature (similar to 25 degrees C). Additions of freeze-dried extracts from ginger rhizomes and fenugreek seeds to beef patties were more effective than potato peel extract in controlling lipid oxidation and color changes during cold storage. (C) 2000 Elsevier Science Ltd. All rights reserved.