Ferrous sulfate microparticles as a food fortification strategy: Application in plant-based yogurt and bioaccessibility assessment

Abstract

This study evaluated the feasibility of using ferrous sulfate microparticles (FSM), produced through the combination of spray drying and spray chilling techniques, to fortify plant-based yogurt and increase dietary iron intake. The stability of FSM was assessed, and iron bioavailability was estimated using the standardized INFOGEST in vitro digestion method, followed by Caco-2 cell culture assays. FSM showed moisture content and water activity (Aw <0.3) comparable to control particles without iron (CP). Despite similar average particle sizes (D50), FSM exhibited lower luminescence and a more greenish-yellow hue than CP. The iron content in FSM and CP was 519 ± 23 mg/kg and 13.5 ± 0.8 mg/kg, respectively. FSM contained 309 mg of soluble iron/kg of particles, corresponding to 59.5 % bioaccessibility. After 180 days of storage, FSM showed slightly higher moisture, Aw, and color values compared to CP, but overall stability remained similar. Total and soluble iron contents did not significantly differ, confirming FSM’s suitability for yogurt fortification. When both plant-based and dairy yogurts were fortified with FSM and isolated ferrous sulfate salt, total iron content ranged from 9.83 to 19.77 mg/kg, with bioaccessible iron ranging from 1.40 to 13.2 mg/kg. Bioaccessibility percentages varied depending on the type of iron (isolated vs. encapsulated), matrix origin (plant-based vs. dairy), and plant-based formulation. Notably, strawberry-flavored plant-based yogurt fortified with FSM showed higher bioavailability than yogurt fortified with isolated salt, emphasizing FSM’s effectiveness in improving iron availability in plantbased yogurts.