Influence of Spray Drying on Encapsulation Efficiencies and Structure of Casein Micelles Loaded with Anthraquinones Extracted from Aloe vera Plant

Featured Application: Novel spray-dried casein micelles microcapsules were developed to extend the stability and bioavailability of anthraquinones extracted from Aloe vera. These microcapsules can be used commercially in food formulations (yoghurt, bakery products and health drinks) while developing functional foods and nutraceuticals to use as laxative, antibacterial, antiviral and anti-inflammatory. The encapsulation efficiency (EE%) and structural changes within the Anthraquinones-encapsulated casein micelles (CM) powders were evaluated in this study. For this purpose, the anthraquinone powder extracted from Aloevera, its freeze-dried powder (FDP) and whole leaf Aloe vera gel (WLAG) has been encapsulated in CM through ultrasonication prior to spray dying to produce nanocapsules: CM encapsulated anthraquinone powder (CMAQP), CM encapsulated freeze-dried powder (CMFDP) and CM encapsulated Whole leaf aloe vera gel (CMWLAG). Based on the pH of the solution before drying, CMAQP had the highest EE% following spray drying. However, due to air-interface-related dehydration stresses, SD resulted in a slight decrease in the EE% of anthraquinones (aloin, aloe-emodin, and rhein) in CMAQP. Meanwhile, a significant increase in EE% of CMFDP was observed compared to the aqueous state. According to SEM findings, the particle size of CMAQP was 2.39 µm and ξ-potential of ~−17mV. The CMFDP had a rough fractal surface with large particle sizes and potential of 3.49 µm and ~−11mV respectively. CM deformed, having the least EE% and lowest ξ-potential (−4.5 mV). Spray drying enhances melanoidin formation in CMWLAG, as evidenced by the highest chroma values. The results suggested that EE%, stability, and degree of Maillard reaction are closely linked to the type of anthraquinone encapsulated, the pH of the solution, and the nanostructure of casein micelles during spray drying.