Method for quantifying alginate and determining release from a food vehicle in gastrointestinal digesta

• Modified PAS assay is suitable for quantifying alginate in synthetic digestion solutions.
• The synthetic model gut is a suitable model for replicating in vivo digestion.
• Modified PAS assay suitable for determining release rate alginate from bread vehicle.
• 80–90% of alginate release in small intestine.

To assess the efficacy of alginate as a modifier of enzyme activity, a suitable method to quantify its release must be developed. This paper develops and assesses the ability of the Periodic Acid Schiffs (PAS) assay to quantify alginate, and its release from bread during digestion in a model gut. Control and alginate enriched (4% w/w wet dough) bread were used. A model gut replicating the mouth, stomach and small intestines was used. Standard curves were created for alginate in deionised H2O and model gut solutions using a modified PAS to remove interference. The PAS assay quantified alginate with excellent linearity (R2 = 0.99), and optical density range (0.02–0.5). There was a significant difference in alginate release at 180 min compared to 0 and 60 min. The data indicate the modified PAS assay is a simple method for quantifying alginate release and release rate from alginate enriched products.