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Effect of high pressure treatment on ovotransferrin

Acero-Lopez, Alexandra, Ullah, Aman, Offengenden, Marina, Jung, Stephanie, Wu, Jianping
Food chemistry 2012 v.135 no.4 pp. 2245-2252
Fourier transform infrared spectroscopy, denaturation, differential scanning calorimetry, enthalpy, fluorescence, high pressure treatment, hydrophobicity, pH, sulfhydryl groups, temperature
High pressure processing of ovotransferrin was carried out to study the structural and physiochemical changes of ovotransferrin under various pressure levels. At pH 8 and pressures higher than 200MPa, a decrease in total sulfhydryl groups and an increase in surface hydrophobicity were observed along with a partial aggregation. A gradual shift of denaturation peak towards higher temperature was noticed up to 500MPa, leading to a total loss of the enthalpy of denaturation at pressures of 600 and 700MPa, where a significant decrease in intrinsic fluorescence was also observed. At pH 3, the ovotransferrin adopted a molten globule state, associated with a significant increase in surface hydrophobicity and reactive sulfhydryl content; structurally, no clear denaturation peaks in differential scanning calorimetry (DSC) were detected at any level of pressure treatment whereas a noticeable decrease in intrinsic fluorescence was evidenced up to 600MPa and then increased at 700MPa pressure treatment. Fourier transform infrared spectroscopy (FT-IR) revealed that the conformational structure were changed from helices, sheets, turns, and aggregated strand to mostly intermolecular β-sheets or aggregated strands at pH 8 at 200MPa but switched back to original structure at higher pressures.