Effects Of Ultral-High Hydrostatic Treatment On Biomacromolecules

In recently years, as consumers pay more attention to the security and quality of food, the traditional method of heat treatment on food is gradually exposed its disadvantage, people started to look for the new technology to replace it. And ultral-high hydrostatic (UHH) technology as a new non-thermal food treatment technology increasingly causes for concern. It is of great significance to study the effects of the ultral-high hydrostatic treatment on the structure the characteristics of biological macromolecules in food; this area has become the leading edge of food ultral-high hydrostatic treatment technology research in the world.In this work, UHH technology has been carried out to investigate biomacromolecules such as protein and starch. Diverse analysis methods have been used to study the effects of UHH on the structure, physical and chemical properties of biomacromolecules. The following conclusions were drawn:(1) As ultral-high hydrostatic treatment and continued pressure would rupture the cell membrane Microbiology, biomacromolecules within the microorganisms were destroyed under the high pressure treatment. Inactivation rate was enhanced with increasing pressure, and microbial inactivation was up to about 99%, besides it increased slowly above 400 MPa. Besides inactivation rate was enhanced with increasing pressure holding time, and microbial inactivation was up to about 99%, besides increase slows above 20 min.(2) Total microorganisms were with the increase of the number of days; there was no significant increase in the number of microorganisms after 20 d above 400 MPa or 20 min.(3) This research suggested that an increase of pressure was associated with an improvement in the solubility and the emulsifying property of the protein under the pressure. Proteins were dissociated into subunits after high pressure processing. The conformations of these subunits had been changed. More sulphydryl groups as well as hydrophobic regions had been found after high hydrostatic treatment.(4) The secondry structure, tertiary structure, and quaternary structure of protein were changed under the pressure; but the primary structure of protein weren't changed under 500 MPa.(5) Ultral-high hydrostatic treatment maked more amylopectin become amylase with smaller molecular weight. The probability of water molecule combined with free hydroxyl was increased since the particles become smaller and larger specific surface area. Therefore, the solubility and transparency of the starch were improved, and the viscosity was decline. At the same time, the rheological property and structure of the starch were improved. Above 300 MPa ultral-high hydrostatic treatment was falled the gelatinization temperature of the starch.(6) The structures of the amorphous areas were changed at the pressure higher than 500 MPa. Then more water comed into the amorphous areas. In addition, the swelling action of the water resulted in the crystal region which connected with the amorphous areas are broken.The research provides us with a more in-depth knowledge on the changes, which occur during the process of ultral-high pressure treatment, not only in the physical and chemical properties of food's biomacromolecules, but also in the structures of them. Thus, this paper is of great value for reference in the UHP food industry.