Browsing by Author "Allén, Marja"

The addition of new oat-based ingredients: beta-glucan, protein and oil was investigated in a beverage product to increase the protein and unsaturated fat content of vegetable drink produced from oatmeal or oat flour. Due the low natural water-solubility of proteins and large molar mass of beta-glucan, these biopolymers do not emulsify oil-in-water emulsion sufficiently and there is a need to add a primary emulsifier. Spruce galactoglucomannan (GGM) has both emulsification and stabilization capacity. The stabilizing effect of GGM has been previously studied on a model of oil-in-water emulsion system. In the present study, the stabilizing properties of GGM was studied in a beverage model where oat protein and beta-glucan were added in an oat oil emulsion system. Heat treatment is an essential part of manufacturing commercial beverages and therefore the effect of pasteurization on GGM-stabilized emulsion was also studied. The literary survey explores the ingredients used in commercial beverages and studies of beverage manufacturing. The literary survey also presents the properties of GGM and other ingredients used in experimental part and the factors affecting emulsion stability. The product model was prepared in a two-stage process in which the GGM emulsified oat oil-in-water emulsion (O) and protein (P) and beta-glucan suspensions (B) were prepared separately and mixed together into beverage product models, OP and OPB. The droplet size was measured from the oat oil emulsion (O). Morphology was examined with an optical microscope from both the emulsions and the product models. The effect of the time on the stability of the product models was determined by measuring the separation of phases. The factors affecting stability were determined also with rheological viscosity measurements and turbidity measurements. The oat oil emulsions’ (O) morphology was homogenous and the average droplet size was small. In product models OP and OPB the homogeneity of emulsions was lost and large undissolved particles or particle clusters were visualized. The oil droplets were seen between the particles and around the particle clusters as small droplets packed in to the spaces between and on the surface of the particle clusters. The viscosity was the highest in the composition OPB and the effect of the time on the viscosity was the most notable. The pasteurization increased the viscosity in the composition OPB compared with the unpasteurized samples. The pasteurization generally increased the stability. There was no oil layer at the top of the beverage models OP and OPB which indicates that the morphology of the oil droplets did not break down during the evaluated shelf-life. The color of produced beverage emulsion resembled that of café au lait. Water separated during storage was easily mixed back with the beverage product model after shaking.