| Abstract [eng] |
Double W1/O/W2 emulsions have a huge potential as carriers for bioactive materials. Such emulsions with encapsulated β-galactosidase (lactase) could be used in dairy products and protect lactose intolerant consumers from unpleasant sensations caused by lactase deficiency. Therefore the aim of this study was to prepare stable double W1/O/W2 emulsions with encapsulated lactase in the inner aqueous phase W1 and a double layer of biopolymers in the outer aqueous phase W2 and to evaluate the release of lactase form the double emulsion during in vitro digestion. The first objective was to evaluate the interactions between whey proteins (WP) and pectin. This interaction was evaluated by mixing 1% WP solutions (WPS) of different pH (from pH 2 to pH 7) and pectin solutions of different concentrations (from 0.1 % to 1%) and comparing the clarity and turbidity of the mixtures and by measuring the ζ-potential of selected solutions. Visually the best interactions were in the mixtures prepared with pH 2, pH 6 and pH 7 WPS and where the ratio of WP and pectin was 10:4; 10:6 and 10:8 respectively. The ζ-potential of these solutions showed that electrostatic attractions can only happen in the mixtures with pH 2 WPS. In the next phase double W1/O/W2 emulsions with a double layer, comprising of WP and pectin, were prepared. They differed in the ratio of WP and pectin in the W2 phase (10:4; 10:6 and 10:8), and the pH of the used WPS (pH 2, pH 6 and pH 7). These emulsions were evaluated by the following parameters: gravitational stability, viscosity and particle size. In the emulsions, prepared with pH 6 and pH 7 WPS, the pectin acted as a gelling agent but did not improve their stability. Emulsions prepared with pH 2 WPS had the best gravitational stability, lowest and constant viscosity, smallest and most even particles because of the electrostatic complex between the WP and pectin. Therefore, lactase was encapsulated into them. Their digestibility and lactase release from them was determined during simulated in vitro digestion by determining the amount of free fatty acids and the decrease of lactose in the digested mixture. It was determined that over 98 % of lactase was encapsulated into the W1 phase. During the in vitro digestion over 35 % of fats were hydrolyzed, however the lactase was not released, probably because of the complex formed between the lactase and the hydrophobic emulsifier PGPR used for the production of these emulsions. Therefore, these emulsions are not suitable to be used for the encapsulation of enzymes. |
