Gerald Muschiolik

Effect of structural changes on foaming properties of soy proteins

Abstract An approach has been used to improve the functional properties of soy proteins using mechanolysis (vibrating mill). The results indicate a close relationship between structural changes dependent on the duration of milling and the foaming properties of the investigated sample. It was observed that the solubility, amount of free amino groups, surface hydrophobicity and lipid content decreased with the extent of modification. RP-HPLC results show that in the early stages of mechanolysis, the protein molecule becomes hydrophobic. In the latter stages changes in functional properties such as foaming and water binding capacity could be observed possibly due to release of hydrophilic components. SDS—PAGE and GPC results show that changes in molecular weight due to mechanolysis can be classified depending on length of modification time in three transitional phases (dissociation, aggregation and degradation). The results of particle analysis confirms that a decrease in particle size correlates with an improvement of the foaming properties.

Foaming properties of modified faba bean protein isolates

Abstract The foaming properties of native and modified faba bean ( Vicia faba ) protein isolates were investigated. Foam stability was studied using both a micro-conductimetric/sparging and a whipping method. Samples were defatted by either supercritical carbon dioxide or isopropanol extraction, both of which produced an increase in the foam stability. Increases in foam stability were also observed for acetylated and mechanolyzed (ball milled) samples. The latter produced the more marked effect. Samples with differing degrees of mechanolyzation were examined, the most highly mechanolyzed samples displaying the greatest foam stability. Studies using circular dichroism spectroscopy showed a correlation between the observed change in functional properties and the secondary structure of the faba bean protein. The robustness of foams formed from several of the treated samples was investigated by assessment of the stability of the foams against destabilization by competitive adsorption of the lipid analogue lysophosphatidylcholine. Again the mechanolyzed sample possessed the best foaming properties in the presence of this competitive surfactant.

Functionality of Different Protein Products in Meat Emulsions with Reduced NaCI Content

Meat emulsions (ME) were prepared using different sodium chloride content and with different whey and plant protein products (soya, faba bean). Rehydrated protein products (PP) were added to ME. The influence of protein functionality parameters (solubility, emulsification, gelation, water absorption) on ME properties (consistency of raw and cooked emulsion, cook loss) was calculated by rank correlation and regression analysis for a range of solubilities of the protein products (PP). Rank correlation shows only a low dependence. Regression analysis gives more information on interactions if performed for highly or moderately soluble PP. Tests of other applications demonstrate that the kind of preparation of ME is of importance for improving the techno-functionality. ME with reduced NaCl content shows better fat binding (emulsification) if liquid meat fat is emulsified with PP solution and then mixed with meat. For improving the water and fat binding of ME with reduced NaCl content it is important to take into consideration the functionality mechanisms of added proteins (surface activity, gelation, swelling) in order to select a suitable application technology (preparing pre-emulsion, adding protein powder or solutions to ME).