Effects of pulsed electric fields (PEF) on structural modification and surface hydrophobicity were assessed for whey protein isolate (WPI) of protein concentrations (3% and 5%) using fluorescence spectroscopy. The effects of a factorial combination of electric field intensities (12, 16, and 20 kV cm −1 ) and number of pulses (10, 20, and 30) on the intrinsic tryptophan fluorescence intensity, extrinsic fluorescence intensity, and surface hydrophobicity of WPI were evaluated. PEF treatments of WPI resulted in increases in the intrinsic tryptophan fluorescence intensity and led to 2-4-nm red shifts in emission wavelengths, indicating changes in the polarity of tryptophan residues microenvironment in whey proteins from a less polar to a more polar environment. The extrinsic fluorescence intensity of WPI increased with PEF treatments, but with 2-4-nm blue shifts, indicating partial denaturation of WPI fractions and exposure of more hydrophobic regions under these PEF treatments. Thus, under the conditions studied, PEF treatments of WPI yielded increases in surface hydrophobicity. The study confirmed that PEF treatments resulted in whey protein structure modifications. These results suggested that controlled PEF could be applied to process liquids food including WPI ingredients and modify their structure and function in order to get desired food products.

BACKGROUND: In this study the effects of pulsed electric field (PEF) pretreatment were evaluated during drying and rehydration of carrots. Carrots pretreated with an electric field intensity of 1 kV cm −1 (capacitance 0.5 µF, 20 pulses) or 1.5 kV cm

No abstract

No abstract