This study focused on a microwavable bunburger consisting of a precooked burger in a bread bun. The objective was to assess whether burger formulation changes would affect selected thermal and dielectric properties of the precooked burgers in addition to affecting bunburger temperatures during microwaving. Control burgers and those with elevated fat, water, rusk and salt levels were prepared. Proximal analysis of the raw and precooked burgers revealed a reduction in the fat and moisture content differences following deepfrying. However, burger formulation influenced (P<0.05) the measured thermal and dielectric properties of the precooked burgers in addition to affecting temperatures (P<0.05) from the burger edge and the top and bottom buns. Temperatures from the burger center were not affected (P< 0.05). Adjusting composition does offer the manufacturer a method to alter temperature during microwave heating through the magnitude of the temperature changes observed in this work were small.

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It is demonstrated that there can be only one driving potential for the movement of water through wood and this will be a function of wood state. On the assumption that the driving potential is the partial pressure of water vapour, a theoretical expression is derived for the diffusion coefficient. Such expression is fitted to diffusion coefficients for Scots pine and a remarkably good fit is obtained. Symbolsa reciprocal mean radius of curvature of a capillary meniscus; also taken to be the radius of the corresponding exposed liquid surface, m b spacing between flow paths in the cell wall, m D diffusion coefficient for water in wood with vapour pressure as the driving potential, kg/ms Pa D~ diffusion coefficient for water vapour through air, kg/ms Pa D O diffusion coefficient for water in wood with the driving potential 0 D o diffusion coefficient for water in wood with the driving potential q~ D O diffusion coeficient for water in wood with vapour pressure as the driving potential, which is associated with leakage paths through the wood, kg/ms Pa Df diffusion coefficient for water in wood with vapour pressure as the driving potential, corresponding to fibre saturation and with no leakage paths, kg/ms Pa D~ diffusion coefficient for water in wood with vapour pressure as the driving potential, which is associated with the constriction of the vapour flow as it approaches the cell wall, kg/ms Pa D~ diffusion coefficient for water in wood with moisture content as the driving potential, kg/ms ~, diffusivity for water vapour in air, m2/s F flux of water, kg/m 2 s p partial pressure of water vapour, Pa R specific gas constant for water, J/kg K r fractional relative humidity T temperature, K x length coordinate in direction of flow, m 7 the dimensionless ratio Df/D c evaluated at r= 1/e 0 arbitrary driving potential for movement of water in wood 2 cell spacing in the direction of water flux, m 0 density of liquid water, kg/m 3 cr coefficient of surface tension, N/m ~b arbitrary driving potential for movement of water in wood co fractional moisture content 402

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