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Browsing by Subject "faasierottuminen"

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  • Tervilä, Miia (2022)
    The physical stability of plant-based beverages is often weak and is used to be improved by food additives. β-glucan and dextran are hydrocolloids that have been found to increase fluid viscosity and therefore may have the potential to replace E-coded hydrocolloids. The aim of this master's thesis was to investigate the effects of oat β-glucan and microbiologically produced dextran on the physical stability of a drinkable oat snack. In addition, the aim was to determine the importance of the molecular size and concentration of β-glucan for its stabilizing ability. The oat base without any added hydrocolloids served as a control. β-glucan and dextran were added to the oat base as extracts so that they replaced a certain volume of oat base water. To determine the concentration effect of β-glucan, an oat beverage containing a high molecular weight β-glucan extract extracted from oat bran was prepared in three different extract concentrations. To determine the effect of the molecular weight, an oat beverage containing an enzymatically hydrolyzed low molecular weight β-glucan extract was prepared. The effects of dextran were studied by preparing oat beverages containing exopolysaccharide extract (EPS) (dextran positive and negative sample). Samples were stored in a refrigerator for 14 days, during which time their stability was characterized by observing phase separation and measuring viscosity, particle size and turbidity. The stability of the beverage samples decreased because of sedimentation, leading to the visual phase separation at the top of the samples. The high molecular weight β-glucan extracted from the oat bran reduced sedimentation and phase separation, and stability and viscosity increased as the extract concentration increased from 5% to 7.5%, with almost invisible phase separation in the latter. Thereafter, increasing the extract concentration to 10% no longer reduced the phase separation, but resulted in a decrease in viscosity during storage. Low molecular weight β-glucan (extract content 10%) did not increase the stability of the oat base, and the viscosity of the sample decreased by about 60% during storage. The decrease in viscosity in these samples may be due to the aggregation of proteins and / or β-glucan due to the higher β-glucan content. The effects of dextran on the stability of the oat beverage remained unclear, as the dextran-positive and negative samples did not differ significantly in viscosity or phase separation, so further studies are needed. Based on this thesis, high molecular weight β-glucan appeared to be a potential substitute for food additives in oat-based beverage applications.