Thermal stability of encapsulated rice bran phytonutrients
Bioactive compound stability can be affected by temperature. Thermal degradation of encapsulated rice bran phytonutrients was studied at two different temperatures (70°C and 80°C) for all type of capsule (1:10 to 1:40 core:coating material ratio). Rice bran phytonutrients content were calculated for every 10 min of heating to investigate the degradation rate. The values were then compared to initial value, giving in % of total rice bran phytonutrients content left in the solution. Figure 5 (a) shows percent of rice bran phytonutrients content from initial value after heating at 70°C while Figure 5 (b) shows percent of rice bran phytonutrients content after heating at 80°C. Both of the heating temperature shows degradation of rice bran phytonutrients for all capsule types but it is shown that rice bran phytonutrients degrade faster at 80°C.
From this study, we also found that the degradation of rice bran phytonutrients is different for all types of capsule. All capsule types show certain amount of rice bran phytonutrients at 70°C and 80°C after 60 min heating core:coating material capsule with the ratio of 1:10 contained lowest total phenolics (8.6% and 4.1%, respectively) where that of the capsule with the ratio of 1:30 contained the highest total phenolics (37.9% and 27.8%, respectively) at 60 min heating.