Protein resynthesis catalyzed by alpha-chymotrypsin was studied to modify the nutritive quality and physical properties of albumin. The increase in substrate concentration produced an increase in enzyme synthetic action. At low substrate concentration, several water activity depressing additives (salts or polyols) in the reaction media enhanced plastein synthesis. Polyols enhanced the synthetic reaction proportionally to an increase in their molecular size. The positive effect of alkali halides was related to an increase in cation size and decrease in anion size. All plastein products showed a clear increase in nutritional value with respect to the substrate.

Water affects safety, stability, quality and physical properties of food. The influence of water on physical properties of food is dependent on the state of water in food. The state, expressed as water activity, is briefly discussed in the paper. Further, the influence of water on such physical properties as rheological, thermal, mass transfer, electrical, optical and acoustic is presented in details.

A bibliographic search yielded a set of empirical equations that constitute an easy method for the calculation of some thermophysical properties of both liquid water and ice I, properties that are involved in the modeling of thermal processes in the high-pressure domain, as required in the design of new high-pressure food processes. These properties, closely interrelated in their physical derivation and experimental measurement, are specific volume, specific isobaric heat capacity, thermal expansion coefficient, and isothermal compressibility coefficient. Where no single equation was found, an alternative method for calculation is proposed. Keeping in mind the intended applications and considering the availability of both experimental data and empirical equations, the limits for the set of equations where set in -40 to 120 degrees C and 0 to 500 MPa for liquid water and -30 to 0 degrees C and 0 to 210 MPa for ice I. The equations and methods selected for each property are described and their results analyzed. Their good agreement with many existing experimental data is discussed. In addition, the routines implemented for the calculation of these properties after the described equations are made available in the public domain.