Effect of sugar replacement with stevia on quality of vanilla flavoured cow milk set yoghurt

Abstract

Stevia extracted from the leaf of Stevia rebaudiana Bertoni plant is a natural alternative sweetener that has the potential to be used as a sugar replacer in sweetened dairy products. The current study aimed to investigate the effect of sugar replacement with stevia extract on the quality of vanilla flavoured cow milk set yoghurt. Cow milk was standardized to 3% fat and 12% milk solids non-fat. Commercially available pure stevia extract was used to replace the sugar (maintained at 8% in the control) at the rate of 0 (control), 25% (T1), 50% (T2), 75% (T3) and 100% (T4) in cow milk set yoghurt. Yoghurt mixtures were separately heat treated (85°C/30 mins), cooled to inoculation temperature (42°C), inoculated with commercial yoghurt culture containing Streptococcus thermophilus and Lactobacillus delbruekii subsp. bulgaricus (1:1 ratio) and incubated till the pH reaches nearly 4.6. Set yoghurt samples were tested for chemical composition, organoleptic attributes, physicochemical and physical properties using standard procedures. Total calorie content was calculated per 100 g of yoghurt. Milk fermentation characteristics, water holding capacity and instrumental colour of yoghurt were not affected (p>0.05) by the sugar replacement with stevia. Carbohydrate content showed a decrease while protein and ash showed an increasing trend with an increasing level of sugar replacement in yoghurt. A 100% sugar replacement with stevia resulted in a 16.83% reduction in the calorie content of yoghurt. Control, as well as 100% sugar replaced yoghurt, obtained higher sensory scores while in the other treatments a decreasing trend in the sensory score was observed with the increasing level of sugar replacement suggesting possible interaction of stevia compounds with sucrose. It can be concluded that the replacement of 100% sugar is possible with the commercially available stevia extract used in the current study for the production of vanilla flavoured set yoghurt.