The effect of spray-drying inlet conditions on iron encapsulation using hydrolysed glucomannan as a matrix

Abstract

Spray-drying is an encapsulation method that can be used to protect iron from oxidation. Hydrolysed glucomannan has shown potential as an encapsulant due to its ability to form a fine, dense network upon drying. The aim of this study was to evaluate the potential of hydrolysed glucomannan as a matrix for iron at inlet air temperatures of spray-drying of 110°C, 120°C, 130°C and 140°C. The physicochemical properties and performance of the iron encapsulation powder were determined. The results indicated that the inlet air temperature influences the properties and performance of the powder. An increase in the inlet air temperature from 110°C to 140°C led to a greater loading capacity and particle size distribution but had an insignificant impact on the moisture content, solubility and swelling. Higher drying air temperatures tended to produce a darker powder. The morphological analysis revealed that higher inlet drying air temperatures produced powders with rounder shapes, whereas lower temperatures produced irregular shapes that tended to form deep concavities on the powder surface. The samples from all inlet temperatures showed similar functional groups but in different intensities. The release of iron at pH 6.8 was higher for the lower inlet temperatures. Samples with the highest inlet temperature showed the highest performance in protecting iron from oxidation. Considering the performance, 130°C is recommended as the inlet air temperature for iron spray-drying encapsulation using hydrolysed glucomannan.