FUNCTIONAL PROPERTIES OF SOY PROTEIN ISOLATE-HYDROXYPROPYLMETHYLCELLULOSES (HPMC) INTERACTIONS AFFECTED BY DYNAMIC HIGH-PRESSURE TREATMENT

MARTÍNEZ, KARINA D.; GANESAN, VYKUNDESHWARI; PILOSOF, ANA M.R.; HARTE, FEDERICO M.

Anaheim, California, Estados Unidos

Congreso; Institute of Food Technologist 2009 (IFT) Annual Meeting + Food Expo; 2009

Institute of Food Technologist

High pressure homogenization (HPH) affects the three-dimensional conformation of food proteins and thus their functionality. Most foods contain protein and polysaccharides and their interactions may affect the stability and rheology of the system. The objective of this study was to determine the effect of HPH on the functional properties of soy protein-polysaccharides mixed systems using a commercial soy protein isolate and hydroxypropylmethyl-cellulose (HPMC; surface active polysaccharide) to make dispersions at pH 7. soy protein isolate (SPI; 90% protein) was dispersed with water (2% w/v) together with  HPMC (0.3% w/v) from two different molecular weights (E15 and E4M). The samples were subjected to HPH from 0 to 300 MPa, in 100 MPa intervals. After HPH, viscosity, particle size distribution, foaming and interfacial properties were determined. SPI viscosity was reduced significantly at 100 MPa from 9.4*10-3 to 2*10-3 Pa.s. Changes in viscosity of high molecular weight HPMC (E4M) (from 0,01342 to 3,53E-03 Pa.s) revealed structural modifications that were not apparent for the low molecular weight HPMC (E15) (from 1,71E-3 to 1,71E-3 Pa.s). The mixed systems showed different initial behaviour depending on the HPMC added, however, at 100 MPa HPH pressure all samples exhibit reduced viscosity (SP-E15: 0.0026 Pa.s; SP-E4M: 0.004960 Pa.s)  that continue decreasing as HPH pressure increased. Foam overrun was increased for SPI alone from 85% to 100%, whereas the mixed systems did not show differences as determined by HPH. Surface pressure increased with HPH in all samples with an average of 23.230 to 26.930 mN/m. Monomodal particle size distribution was observed in all cases. SPI increased the size at 100 MPa from 0.131 mm to 8.816 mm and decreased with the pressure at 0.150 mm. However, the mixed system, showed a higher initial particle size  of 20.087mm that decreased with increasing HPH pressures at 0.172 mm. Due to the lack of HPH effect on mixed protein-polysaccharide systems, it is relevant to identify the potential of this technique to create new functional macromolecules derived from hydrophobic and/or electrostatic interactions between these molecules.