Microencapsulation Properties of Gum Arabic and Several Food Proteins:  Spray-Dried Orange Oil Emulsion Particles

The encapsulation properties of several commercial food proteins and gum arabic (GA) were evaluated by conventional analytical procedures and dynamic headspace analysis (DHA). The microstructural properties of spray-dried microencapsulated orange oil emulsion particles were investigated by scanning electron microscopy (SEM) and confocal scanning laser microscopy (CSLM). Soy protein isolate (SPI) was most effective and whey protein isolate (WPI) least effective for retaining orange oil during spray-drying of the liquid orange oil emulsions. Spray-dried SC-microencapsulated particles exhibited the largest sizes, and the sizes of the other microencapsulated orange oil particles were in decreasing order of WPI > SPI > GA. SEM and CSLM results revealed that spray-dried GA-microencapsulated orange oil particles had undergone more shrinkage during drying than the protein-microencapsulated products. A modified DHA technique was developed to determine the rate of release of volatiles from the spray-dried, microencapsulated orange oil emulsion particles. DHA results revealed that GA-microencapsulated particles had the highest volatile release rate and SPI-microencapsulated particles the lowest release rate as determined by DHA. WPI- and SPI-microencapsulated orange oil products were more stable against oxidation than SC- and GA-microencapsulated orange oil products. It was concluded that GA and SC were least effective as orange oil microencapsulants on the basis of DHA results and WPI and GA were least effective as orange oil microencapsulants on the basis of total oil retention and surface oil results. Keywords: Encapsulation; flavor release; protein; microstructure; dynamic headspace analysis