Microencapsulation of Moringa oleifera leaf extracts with vegetable protein as wall materials

Moringa oleifera, often referred to as 'miracle tree' contains high amount of bioactive nutrients and dietary antioxidants, which help in ameliorating oxidative stress and degenerating diseases. However, the bioactive compounds are highly susceptible to degradation, and this may decrease the antioxidants activity present in M. oleifera. To prevent these limitations, the utilisation of microencapsulation technique is of necessity. This study investigated the effect of two vegetable proteins: soy protein isolate and pea protein isolate as wall materials for M. oleifera leaf extracts encapsulation by spray drying technique. Three inlet air temperatures (140, 160, and 180 celcius) and two different formulations of core:wall material ratios (1:4 and 1:9, w/w) were studied. The total phenolic contents, antioxidant activity, microencapsulation yield, morphology, colour, tapped and bulk densities, particle size, and storage stability of M. oleifera microcapsules were analysed. Moringa microencapsulates with pea protein isolate had better powder quality than Moringa microencapsulates with soy protein isolate considering its significant higher particle size, bulk and tapped densities. Moringa microencapsulates with soy protein isolate proved to be a better carrier of bioactive compounds of both total phenolic content and 2,2-diphenyl-1-picrylhydrazyl activity at inlet air temperature in the range of 140-180 celcius. The total phenolic content and 2,2-diphenyl-1-picrylhydrazyl activity tend to be the most stable compound. The storage stability of bioactive compounds of both Moringa microencapsulates with pea protein isolate and Moringa microencapsulates with soy protein isolate was better preserved at 4 celcius compared to that of 25 celcius.