| Abstract [eng] |
The aim of this study was to determine the possibilities of encapsulation of sea buckthorn extracts with different properties into hardened, whey protein stabilized double emulsions and whey protein and konjac glucomannan aerogels. The following systems were investigated during the research: 1) multiple emulsions with loaded lyphophilic sea buckthorn extract in phase A and hydrophilic sea buckthorn extract in inner aqueous phase V₁, in which the ratio of extracts (30/20 and 20/20), second homogenization time (10, 20, 30, 40 min.), inner and external phases ratio (40:60), external aqueous phase stabilized with 15 % whey protein isolate; 2) Konjac glucomannan hydrogels prepared with different concentrations (0.1, 0.2, 0.3 and 0.4 M) of Na₂CO₃ solutions for deacetylation of KG molecules; 3) Konjac glucomannan (KGM) deacetylated with different concentrations (0.1, 0.2, 0.3, 0.4 M) of Na₂CO₃ solutions and 20 % whey protein isolate based aerogels with loaded sea buckthorn extracts. These parameters were evaluated in (heat-induced and not heat induced) multiple emulsions gels: rheological characteristics, kinetic of external aqueous phase, color, particle size and distribution, antioxidant activity, sensory properties; Konjac glucomannan hydrogels studies: swelling ratio, texture profile, rheological characteristics, influence of Na₂CO3 on hydrogel hardness and viscous elasticity properties; in the studies of konjac glucomannan and whey protein isolate-based aerogels: was porosity and morphological view was established, absorption of hydrophilic extract, antioxidant activity, encapsulation efficiency, color, texture profile. Double emulsions have been found to be suitable systems for encapsulating lipophilic and hydrophilic sea buckthorn extracts when whey protein isolate is used in the external aqueous phase (V₂), as whey proteins form an irreversible gel during heat treatment, thereby hardening and stabilizing the emulsion. Double emulsions, encapsulated with lipophilic and hydrophilic sea buckthorn extracts, have good antioxidant properties, which decrease steadily during storage at (20 ° C). The prolongation of the homogenization time results in a decrease in the particle size and viscosity of the uncoated emulsions, but no effect of the homogenization time on the properties of the crosslinked emulsions was observed. More pronounced differences were observed in the determination of color characteristics, where emulsions with a ratio of 30/20 lipophilic to hydrophilic sea buckthorn extract were obtained yellowish than emulsions with a ratio of 20/20 extracts. The properties of konjac glucomannan hydrogels depend on the concentration of sodium carbonate used for deacetylation. The sodium carbonate solutions used in the preparation of the hydrogels were dominated by an alkaline environment with pH ranging from 0.1 M (10.29 ± 0.04) to 0.4 M (10.65 ± 0.01). During storage from 0 to 240 hours, the water uptake ratio of the hydrogels increases. Hydrogels with a concentration of 0.1 M have better water absorption properties, which decrease steadily with increasing sodium carbonate concentration. The elastic properties of irreversible thermogels increase with increasing Na₂CO₃ concentration from 0.1 M (7163 ± 1.550 Pa) to 0.4 M (322433 ± 3.528 Pa), as well as texture profile indicators, including hardness, stickiness, chewability, recovery. The properties of aerogels depend on the type of biopolymer used in their preparation and the drying conditions. The pores in the konjac glucomannan aerogels are irregular in shape and the total pore volume depends on the concentration of sodium carbonate used in their preparation, which increases the total pore volume by 0.2 M (0.026 cc/g). 0.3 M (0.028 cc/g) and further increasing to 0.4 M decreases (0.019 cc/g). The pores in the aerogels of 20% whey protein isolate are spherical with a total pore volume of 0.135 cc / g. Konjac glucomannan and whey protein aerogels are suitable systems for encapsulating hydrophilic sea buckthorn extract due to their ability to absorb hydrophilic sea buckthorn extract. In konjac glucomannan aerogels the ratio of extract absorption during storage (0.5 - 15%), and in whey protein aerogels (0.3 - 2.5%). |
