Evaluation of physico-chemical properties and antioxidant activity of stirred yoghurt fortified with pomegranate and cactus pear juices

Abstract EN

This study was carried out to estimate the effect of adding pomegranate (Punica granatum L) and cactus pear (Opuntia ficus indica) juices as natural ingredients on physico-chemical characteristics, antioxidant activity, microbiological examination and sensory evaluation of stirred yoghurt.

Stirred yoghurt was prepared by using cow^, s milk 3% fat, and pomegranate and cactus pear juices were added at the rate of 5% , 10% and 15% W/W.

All treatments were inoculated with 2% of yoghurt starter and stored at 5°C up to the end of storage period (15 days) after complete a sulation.

Physico-chemical properties of yoghurt samples such as total solids, protein, fat, pH, syneresis, viscosity was carried out.

Also, microbiological examination and sensory evaluation were determined of all the treatments when fresh, and then after 5, 10 and 15 days of cold storage at 5°C.

The results showed that significant differences were found between the control and stirred yoghurt fortified with juices in the total solids, protein content, pH and titratable acidity up to the end of storage period(15 days).

Addition of pomegranate and cactus pear juices led to significant increase in phenolic compounds and antioxidant activity of yoghurt treatments compared with the control sample.

In all samples, it was observed that the titratable acidity increased over the storage period.

Low values for viscosity and high values for syneresis were belonged to yoghurt containing 15% pomegranate and cactus pear juices.

Sensory evaluation results showed that there were significant differences among the yoghurt samples.

Stirred yoghurt (control) and stirred yoghurt containing 5% cactus pear or pomegranate juices gained significantly highest flavour and texture scores compared to stirred yoghurt treated with 10% or 15% juices.

The results of current study demonstrated that the addition of juices from pomegranate and cactus pear to stirred yoghurt milk, significantly improved the quality of yoghurt and will increase its healthy benefits.