Quality and Physiochemical Properties of Banana Paste under Vacuum Dehydration

This research aimed to develop a prototype of an evaporative dehydrator and demonstrate the effect of quick evaporative dehydration on the physiochemical properties of banana paste. The study was divided into 2 parts. The first part was focused on the development of the evaporative dehydrator prototype. After several modifications, the prototype of an evaporative dehydrator was successfully constructed to enable the variation of banana paste sample prior to evaporation using two types of evaporative stresses (i.e., atmospheric and vacuum conditions). The second part was to study the effect of evaporative dehydration on the physiochemical properties of banana paste comparing vacuum and atmospheric conditions. The temperature setting for the heating section was varied at 30, 40, 60, 80, 100 and 120 degree Celsius and the physiochemical alteration of the banana paste sample was monitored. The peroxidase enzyme was found to be active in all treatments. The evaporative cooling in the vacuum treatment caused the temperature of the final product to be lower than that of the atmospheric treatment. The moisture content also seemed to be lower and the water activity was less. Although the acidity remained stable and was not differentiable between the two treatments; the different evaporative conditions had a profound effect on other physiochemical properties, especially the external appearance of the final product. The visual appearance was determined by the Hunter indices (L, a, and b) and delta E (overall color change). As the operating temperature increased, the delta E in both treatments increased. The sample in the vacuum treatment became darker (lower L-value) and more intense in yellow color (higher b-value). This was hypothesized to be the result of product condensation due to moisture loss. The a-value decreased as the operating temperature increased and there was no significant difference between the two treatments. The viscosity of the final product had a unique profile regarding the operating temperature variation. It appeared to be more viscous than the fresh sample at low temperature. For the higher temperature setting, the viscosity decreased as the temperature increased. Enzymatic and non-enzymatic chemical reactions might be responsible for the alteration of the flow characteristics of dehydrated sample rather than the sole effect of moisture reduction.