Micronutrient Premix Granules: Characterization, Failure Analysis, and Application in Fortified Bouillon Cubes

Abstract

Micronutrient premix granules, originally designed to fortify iodized salt with iron, have proven effective in reducing the prevalence of iron deficiency. Building on the success of fortified salt, there is potential for premix granules to fortify other food vehicles, such as bouillon cubes. However, knowledge of premix granule properties and their operational range remains limited. Current premix granule formulations consist of an extruded core containing micronutrients and durum wheat semolina, encased in a colour-masked and hydrophobic coating. This thesis explores four aspects that could broaden the application ofmicronutrient premix granules: physical and cross-sectional characterization of the granules; the thermodynamic behaviour of the coating in the presence of another fat; granule attrition due to mechanical impact; and a bench-scale production of bouillon cubes fortified with premix granules. Cross-sectional analyses revealed micronutrient cores measuring 500- 900 μm in diameter, with hydrophobic coatings 25-40 μm thick. The fully hydrogenated soybean oil in the premix coating resists melting in processes operating below 65 ◦C. During processing, given sufficient contact time to reach equilibrium, the fully hydrogenated soybean oil coating interacts with other fats in the food product, such as palm stearin, forming a binary fat coating. This resulting palm stearin/fully hydrogenated soybean oil binary fat premix coating is easily deformable. Premix granules smaller than 600 μm in diameter demonstrate greater resistance against attrition from mechanical impact. The practical application of this work yielded encouraging results in producing fortified bouillon cubes at the bench scale. In conclusion, the addition of premix granules presents a promising approach for fortifying bouillon cubes with various micronutrients.