Effect of added bovine casein and whey protein on the quality of camel and bovine milk yoghurts

The aim of this study is to evaluate the effect of fortification of camel milk (CM) and bovine milk (BM) with 1-4% of bovine casein (CN) and/or whey protein (WP) on the quality of yoghurts after 12 hours of fermentation. Response surface methodology was used to design the experiment. Yoghurts were evaluated for pH, acidity, hardness and rheology. The results revealed that addition of WP and CN significantly improved the hardness (p<0.000), and the rheological properties; storage modulus (G', p<0.005), and loss modulus (G", p<0.005), viscosity (p<0.005) and tan δ (G''/G', p<0.05) of CM yoghurts. Both types of yoghurts attained highest viscosity, G' and G" values at highest level of WP (4%) and intermediate level of CN (2.5%) while increased CN ratio showed negative effects on yoghurts rheology. It can be concluded that the amount of total proteins as well as altering CN-to-WP ratio are important for the formation of strong gel network and the production of good quality set yoghurts.