The experimental results show different type of oven surface give different values of L*. This indicates that the type
of oven surface give significant effect on the bread colour development during baking process. Thus, suggesting that the
contribution of radiation heat transfer distribution in the oven is important. From the heat transfer theory, it is well known
that radiation heat transfer is dependence on the colour of the enclosure surface. In this case, black and shiny surface were used and therefore give the different results. Black surface has high emissivity which can generate more heat whereby it could also absorbed higher rate of heat that falls on its surface. While small portion of heat is absorbed by the bread surface. This is different with shiny surface which has low emissivity causing the heat to be reflected by the surface and consequently, more heat is gained by the bread surface. As a result, the rate of temperature increase on the bread surface for shiny surface is faster compared to the black surface oven. However, in terms of colour development, it was observed that colour profiles from bread baked in both oven give similar values of lightness (L*) for the first 10 to 15 min and suddenly decreased to the lower values of L* in black surface oven as shown in Figure 6 to 8. Lower values of L* indicate darker browning of bread surface. This reveal that, high surface temperature is not necessarily give more browning to the bread surface and vice versa.