Submitted to: Annual Meeting of the Institute of Food Technologists
Publication Type: Abstract Only
Publication Acceptance Date: 7/28/2007
Publication Date: 7/28/2007
Citation: Singh, M., Byars, J.A. 2007. Rheology of starch-lipid composites yogurts [abstract]. Annual Meeting of the Institute of Food Technologists. Paper No. 054-01.
Technical Abstract: Yogurt is traditionally made by fermenting liquid milk. The ability of starches to thicken, gel, and hold water has been exploited in yogurt manufacture. The addition of starch increases the viscosity of yogurt, but some starches impart an undesirable taste and promote phase separation. Starch-lipid composites (SLCs) consist of a stable suspension of microscopic lipid droplets in a starch dispersion or gel, having the outward appearance of the cooked starch product but incorporating valuable properties of the included oil phase gel. SLCs used in food products have been shown to not impart undesirable flavor, rather on the contrary impart creamy flavor to dairy products. SLCs were used to replace milk solids in yogurt mixes at different levels. The effects of the starch-lipid composites on the yogurt fermentation and rheology were studied. The rate of fermentation was evaluated by the change of pH every two minutes during the fermentation of yogurt. The syneresis of yogurt was observed over three weeks of storage. Controlled stress rheometer was used to obtain small amplitude oscillatory shear flow measurements of the storage modulus G’, the loss modulus G”, and the loss tangent tan delta (= G”/G’) using a vane geometry. Yogurt mixes with milk solids partially replaced by starch-lipid composites (SLCs) fermented at a similar rate than as without milk solids replaced. Initial viscosity was higher for yogurt mixes with higher levels of SLCs. The higher initial viscosity did not affect the gel structure. The addition of SLCs above a level of 3% strengthened the gel and resulted in no syneresis for yogurt samples stored for three weeks at 4 deg C. This study will benefit the yogurt industry by offering alternative methods for yogurt production.