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Abstract:The aim of this work was to characterise influence of whey proteins-pectin interaction on emulsification properties of whey. As the first, structural characteristics of pectin-protein complexes were evaluated for pure β-lactoglobulin by both dynamic light scattering method for measuring of the particle size distributions and Doppler laser electrophoresis for measuring the ζ-potential (surface electrical potential) of particles. In mixed pectin-β-lactoglobulin systems, it was observed that the addition of pectin prevent from the protein-protein interaction, which caused production of huge protein aggregates (2000-2500 nm) at pH values near β-lactoglobulin isoelectric point and at temperatures near its denaturation temperature. However, these protei-pectin complexes had large hydrodynamic diameters (monomodal size distribution at 350 and 1000 nm for high esterified and low esterified amidated pectin, resp.), which can slow down their diffusion to the oil-water interface in emulsions. The ζ-potential values indicated improvement of colloid stability by addition of pectin. The evaluation of the influence of the protein-pectin interaction on emulsification properties was performed by the determination of a surface weighted mean (D [3,2]) of oil droplets in o/w emulsions measured by the laser diffraction, further by microscope observations, the determination of emulsion free oil content and observations of creaming. The emulsifying properties were influenced by the pectin addition, more negatively by the high esterified than by the low esterified amidated pectin addition.

Lisová I., Horáčková Š., Kováčová R., Rada V., Plocková M. (2013): Emulsion encapsulation of Bifidobacterium animalis subsp. lactis Bb12 with the addition of lecithin. Czech J. Food Sci., 31: 270-274.The commercial probiotic strain Bifidobacterium animalis subsp. lactis Bb12 was encapsulated using emulsion encapsulation into milk protein matrix without and with the addition of 0.5% w/w lecithin into the oil. Different agitation speeds were used during the encapsulation process. The examination of microcapsules was carried out by optical microscope and fluorescence in situ hybridisation. The particle size distribution as volume based median d 0.5 was evaluated by the laser diffraction method. In the case of no lecithin addition, the agitation speed did not influence significantly the size of the microcapsules. The addition of 0.5% (w/w) of lecithin into the oil caused a decrease of d 0.5 value from 196 ± 37 µm to 79 ± 3 µm at an agitation speed of 500 rpm, and from 193 ± 24 µm to 39 ± 3 µm at 1200 rpm. It can improve the sensory properties of the products with the added microcapsules.

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