WPI-Dextran and WPI-Galactomanan conjugates, their performance as emulsifiers in oil/water emulsions

PÉREZ, OSCAR E; MORENO, JAVIER; PILOSOF, ANA MR.; LÓPEZ FANDIÑO, ROSINA; VILLAMIEL, MAR

Porto, Portugal

Congreso; International Functional Foods Conference (2008),; 2008

Proyecto CYTED 105PI0274 y Universidad Católica Portuguesa

The formation and stability of emulsions is a key quality parameter in a wide range of applications in food science, since consumer perception of quality is strongly influenced by appearance. Thus, emulsion functionality results highly influenced by the surface and interfacial properties of the surface-active components, i.e. proteins, polysaccharides and surfactants, present in the system and their interactions. Even whey protein concentrates (WPC) and isolates (WPI) are important food ingredients because of their desirable functional properties, such as gelation, foaming and emulsification, it has been shown that polysaccharides were able to enhance the stability and functional properties of proteins. Previous reports have shown that polysaccharides are more effective for enhancing protein functionality than mono, di and oligosaccharides, i.e. the emulsifying properties of the conjugates increased in proportion of the length of the polysaccharide and the binding number. The objective of this research is to explore the behaviour of WPI-Dextran (WPI-Dex) and WPI-Galactomanan (WPI-Gal) conjugates as emulsifying compounds. Different performers were expected for these conjugates due to dextran posses a branched structure The conjugates were obtained by Maillard reaction (60ºC, aw=0.44, 60 h). Emulsions oil (20%)/water (80%) were prepared at 0.4 % wt final concentration of protein and submitted to HIUS (Vibra Cell Sonics, model VCX 750) at a frequency of 20kHz, 20% of amplitude during 20 minutes and at controlled temperature (35- 40 ºC). The size distributions of particles, measured by laser light scattering (Mastersizer 2000, Malvern Instruments), were immediately analyzed and followed for 30 days. Stability parameters of emulsions were obtained. The conjugates were able to generate mcicroemulsiones with very strong stability against oil separation. The differences between WPI and WPI-polysaccharides emulsions were found in the coalescence and flocculation indexes. In general, it can be concluded that WPI-Gal conjugates gave the best performance against coalescence. Single WPI generated emulsions with the lower flocculation index.