80-1 |
Effects of high pressure-low temperature processing on dairy proteins and on ice crystal formation |
B. TAUSCHER, Federal Research Centre for Nutrition, Haid-und-Neu-Strasse 9, D-76131 Karlsruhe, Germany High-pressure treatment is a new preservation method without application of high temperatures, avoiding undesirable alterations caused by thermal treatment of foods such as vitamin and flavour loss, reduced bioavailabilily of essential amino acids, modification of taste and colour, etc. Food processing involves a variety of changes on the molecular level including chemical reactions of food components as a result of the action of physical variables such as pressure, temperature, shear forces, or highly reactive species like oxygen or radicals. Pressure influences reaction kinetics as well as equilibrium thermodynamics: under the influence of pressure, preferentially such reactions take place or those reaction rates are increased, which are linked to a reduction of the volume of the overall system or the activation volume of the particular reaction, respectively . In case of a volume increase reactions are inhibited by pressure and the equilibrium is shifted to the educts. In this review, the effects of pressure on the molecular level on main food components are outlined, including lipids, proteins, enzymes, carbohydrates, polysaccharides, vitamins and other ingredients in meat, fruit, vegetables, cereals, milk and milk products and in model systems. Examples of high pressure sensitive food >relevant reactions, among others lipid oxidation, Diels-Alder-, Maillard-, peptide cyclisation-reactions, enzyme inactivation and phase transition of macromolecules, are given.
Session 80, Ultra high pressure: Molecular changes in foods
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