Abstract

Antioxidant activity of foods is important both for shelf life of the product and also protection from oxidative damage in the human body. Select brands of milk, yoghurt, fresh cream cheese and kefir were screened for antioxidant activity using the DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging and iron chelating activity methods. Fermented dairy products containing types of berries (strawberry, blueberry, blackberry, raspberry) showed higher (p<0.05) antioxidant activity when compared to plain products or containing other fruits. For both methods, the highest antioxidant (p<0.05) activity was observed in fresh cream cheese group.
Key words: DPPH scavenging activity, iron chelating activity, dairy products.

INTRODUCTION

Free radicals and other reactive oxygen species (ROS) can damage all types of cellular macromolecules and can cause cell death and tissue damage (1, 2). The human body has several mechanisms of defence but a high proportion of the antioxidant systems of the human body are dependent on dietary constituents (3, 4).
Milk and dairy products, which are basic foods for human development, can be beneficial for the oxidative defence of consumers by several mechanisms. As oxidation processes in milk can result in strong off-flavours and in deterioration of the nutritional quality of milk, the oxidative stability of milk and dairy products has noteworthy importance. Milk itself and bioactive peptides which are released by hydrolysis of milk proteins during the fermentation process can show antioxidant activity. Antioxidant activity of milk and some dairy products were determined (5-11) but there is still a lack in knowledge for antioxidant capacity of dairy products such as probiotic yoghurt, dairy products containing different types of fruits and especially cheese varieties. Especially fruits contain various bioactive compounds such as vitami ...