Spray Encapsulation of Iron in Chitosan Biopolymer for Tea Fortification

Abstract

Aim. Tea was studied as a carrier for iron in a fortification strategy to reduce iron deficiency. Iron forms insoluble coloured complexes with tea polyphenols which lower consumer acceptability. Complexation of iron by polyphenols and quinones derived from tea inhibits iron absorption in the first segment of the small intestine. Spray-dried chitosan-iron microcapsules were prepared to prevent iron-polyphenol interaction before the beverage is consumed. A competing chelating agent (EDTA) or antioxidant (sodium ascorbate) was added to prevent interactions and help improve iron bioavailability. Methods. The effect of concentration of chitosan (0.2–1.5%w/w), iron loading (10–60% w/w FeSO4), addition of secondary coatings on particle morphology, surface iron exposure and release, and bioaccessibility were evaluated. Tea-containing chitosan microcapsules and chelating agents to enable iron absorption were evaluated for sensory acceptability. Results. The iron release profile at pH 1 and pH 7 exhibited reverse enteric behaviour of non-cross-linked chitosan microcapsules. Increasing the iron content leads to more iron exposure on the surface due to a high core to coat ratio. Cross-linked chitosan effectively encapsulated iron, and its release in tea was inhibited, as indicated by lower delta E values in comparison with untreated tea and positive sensory testing scores. The use of maltodextrin as secondary coating slightly improved the spray process and produced larger particles, with less exposed iron on the surface. However, it did not improve the colour performance in milk tea. Conclusions. Tea fortified with encapsulated iron and a chelating agent providing 40% of the daily iron requirement of an adult, prepared in a traditional South Asian manner, i.e., with milk and water, resulted in tea with acceptable colour and taste. However, further research is required to develop an encapsulation formulation for stable iron encapsulation in hot tea and exploration of equivalent plant-based chitosan sources to address concerns of consumers with dietary restrictions.