Effect of pulsed light treatment on structural and functional properties of whey protein isolate

• Protein structures and functional properties modifications were fluence dependent.
• Pulsed light treatments caused a partial unfolding of WPI.
• Pulsed light irradiation slightly changed protein secondary structure.
• Pulsed light irradiation induced a variation of the protein primary structure.
• Pulsed light treatment improved solubility and functional properties of protein.

This work aimed at investigating the effects of Pulsed Light (PL) processing at different fluences (from 4 to 16 J/cm2) on the structure and functional properties of Whey Protein Isolate (WPI) solution. The determination of the free and total sulfhydryl (SH) groups was used to detect the variation of WPI tertiary and quaternary structure. Additionally, PL-induced changes in secondary structure were determined by FT-IR spectroscopy and the differential scanning calorimetry (DSC), and primary structure by carbonyl content.The experimental data demonstrated that PL treatments increased the concentration of total and free sulfhydryl groups and protein carbonyls. A decrease of the denaturation temperature and enthalpy ratio with increasing the intensity of PL treatments was observed in DSC measurements. Small but significant changes in the secondary structure of PL treated WPI solution were also taking place and detected. The extent of whey protein structure modifications was fluence dependent. The results of this investigation demonstrated the potential of PL treatments to induce dissociation and partial unfolding of WPI, thus improving some of their functional properties, such as solubility and foaming ability.

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