Tomato (Lycopersicon esculentum L.) peel powder as a source of natural antioxidant and a colorant in stirred yoghurt

Tomato (Lycopersicon esculentum L.) peel powder as a source of natural antioxidant and a colorant in stirred yoghurt

Lycopene is the principle carotenoid responsible for red pigment in tomato. Lycopene is proven to indicate many health promoting properties due to its free radical quenching effects in human body. Tomato peel is a rich source of lycopene which can be used as a natural antioxidant and colorant in foods. Tomato peels were freeze dried, pulverized and sieved to prepare fine, light orange colored tomato peel powder. Tomato peel powder (TPP) was analyzed for radical scavenging activity (RSA), total phenolic content (TPC) and total carotenoid yield. Fourier transform infra-red spectroscopy (FTIR) and UV-visible (UV-VIS) spectrum analysis were carried out for TPP comparing with extracted and commercial lycopene. Two batches of stirred yoghurts were prepared by adding TPP at levels of 0%, 2%, 4%, 6%, and 8% (w/w), before fermentation and after fermentation and analyzed for RSA and color. RSA (%) and TPC of tomato peel powder were 50.05±0.66% and 0.38±0.01 mg of gallic acid equivalent per gram of sample (mg GAE g–1), respectively. Total carotenoid yield of the TPP was 7.14±0.01 mg g–1. FTIR and UV-VIS spectrum data confirmed the presence of lycopene in TPP. Significantly higher (p <0.05) overall acceptability was shown by the stirred yoghurt contained 2% TPP. RSA of the stirred yoghurt were significantly increased with the increasing level of TPP. Tomato peel powder (8%) added stirred yoghurt showed the highest color value for redness (18.83±0.37). Results revealed that TPP can be successfully incorporated into stirred yoghurt as a natural antioxidant and a colorant.