2007 Volume 8 Issue 4 Pages 177-190
A novel method to measure viscosity and static shear modulus of viscoelastic food fluids was developed. This method is based on the flow theory of fluid and shear deformation of elastic material in an annular channel. The method, the non-rotational concentric cylinder method, evaluated static viscoelasticity of sample in a cup easily by analyzing the force acting on a plunger immersed in the sample during the period of time of the cup movement for a very short distance at a constant speed to the axial direction. Dependence of apparent viscosity on shear rate is also evaluated by this method. A new emulsification method called the membrane emulsification method combined with preliminary emulsification was developed. The method prepares monodispersed and stable O/W or W/O emulsions easily at a high rate. Mean particle diameters prepared by this method were about two times larger than the mean pore size of the membrane used. The mean particle diameter decreased and mono-dispersibility increased with the increase of permeating flux (or pressure) of pre-emulsified emulsion. Stable and fine particle (ca. 3 μm) multi-phase emulsions such as W/O/W and O/W/O types could be prepared by using this method. The membrane phase inversion emulsification method was also developed by applying the membrane emulsification method combined with preliminary emulsification. This method prepared mono-dispersed and stable O/W or W/O emulsions with very high dispersed phase concentration up to about 80% or more. Characteristics of a newly developed superheated steam (SHS) treatment combined with far infrared heating (FIH) were investigated. Heat transfer rate under steady state condition could be estimated from empirical equations for convective and radiative heat transfer from the SHS and radiative heat transfer from the FIH heater and chamber wall. Very few degradation of edible oil was found in the SHS treatment because of almost no oxygen in the SHS. Carbonization rate of biomaterials treated in the SHS was expressed by the first order rate equation, and the rate increased with the increase of temperature and with the decrease of sample size. Combined treatment of the SHS and the FIH decreased carbonization energy significantly.
