(P06-052-23) Solubility of Common Iron Fortificants With and Without Coextrusion and/or Citric Acid/Trisodium Citrate in the INFOGEST In Vitro Digestion Model

Objectives: To assess the iron solubility of extruded rice flour fortified with iron, citric acid (CA), and trisodium citrate (TSC) in the INFOGEST in vitro digestion model.

Methods: Two food processing strategies were investigated. Iron, CA, and TSC were coextruded with rice flour or mixed with extruded rice flour. Two additional factors were investigated: 1) iron additive - regular ferric pyrophosphate (FePP, [20 µm]), micronized FePP (µFePP, [2.4 µm]) or ferric orthophosphate (FePO4); 2) high 1:0.3:5.5, low 1:0.1:2.1 or zero molar ratio of iron:CA:TSC. Thirteen rice flour samples went through in vitro gastrointestinal digestion and iron solubilities (%) = (soluble iron content/total iron content) x 100 were determined. Results were analyzed with one-way ANOVA and LSD test in SAS Studio v 3.8 (significance at p< 0.05).

Results: Coextruded FePO₄ samples were significantly increased compared to mixed FePO₄ samples, while mixed FePP samples were significantly increased compared to coextruded FePP samples. Among coextruded samples, high ratio FePP and FePO₄ samples were significantly increased compared to low ratio FePP and FePO₄ samples, respectively. High and low ratio FePO₄ samples were significantly increased compared to high and low ratio FePP samples, respectively. Among mixed samples, high ratio samples were significantly increased compared to zero samples, but only the low ratio FePP sample was significantly increased compared to the zero FePP sample. The high ratio FePP sample was significantly increased compared to the low ratio FePP sample, the high ratio FePO₄ sample, and the high ratio µFePP sample. There were no significant differences between high ratio and low ratio FePO₄ and µFePP samples.

Conclusions: Extruded rice flour fortified with high molar ratio of CA and TSC had higher iron solubility and high ratio FePO₄ coextruded rice flour had the highest iron solubility, while the iron solubility of μFePP trended lower than regular FePP. For rice flour fortified with FePO₄, coextrusion was better than mixing, while for rice flour fortified with FePP, mixing was better than coextrusion.

Funding Sources: USDA Multistate W4002 and Kansas State Agriculture Experiment Station