Influence of sweetener stevia on the quality of strawberry flavoured fresh yoghurt

Stevia is a natural, non energetic sweetener, 200-300 times sweeter than sucrose, and is obtained by leaves extraction of the Stevia rebaudiana. According to the low energy value of stevia to sweeten food products, it is a great possibility of its use in the dairy industry. This study examined the differences in the sweetness of the strawberry flavoured yoghurt with the addition of sucrose, stevia and equal portions of sucrose and stevia; each combination was used at three different concentrations (3, 4.5 and 6 % / 100 g yoghurt). Stevia was diluted in a concentration which, according to the literature, matches the sweetness profile of sucrose. Viscosity of the yoghurts was determined by the rheometer, and sensory profiling of the products was evaluated by a panel using the ranking test and weighted factors methods. The level of sweetness of all yoghurt samples (using sucrose, stevia and mixture of sucrose and stevia) was judged by a test panel, and products were rated in the terms of degree of sweetness as sucrose > sucrose + stevia > stevia. The recommended level by panelists of any type or combination of sweeteners for strawberry yoghurt was 4.5 g sweetner/100 g. The apparent viscosity was lower in sucrose yoghurts compared to products made with stevia or stevia + sucrose which was also reflected in the sensory scores.