Kinetic modeling of four folates in a model solution at different temperatures and pH to mimic their behavior in foods during processing

Abstract

This study aims to generate new kinetic data on 4 folate forms, namely folic acid (FA), 5-methyl-tetrahydrofolate (5MTHF), 10-formylfolic acid (10FFA) and tetrahydrofolate (THF) in the same conditions: model media at three temperatures (60°C, 80°C, and 100°C) and three pH values (3, 5, and 7). For the four forms, degradation could be described using a first-order model. At 100°C and pH 3, rates were 2.8 × 10−2, 1.6 × 10−2, 1.8 × 10−3, and 4 × 10−5 min−1 for 5MTHF, THF, 10FFA and FA respectively. Therefore, the reactivity could be modulated by a factor of 2, 10, and up to 200-fold for folic acid. pH increase had a positive effect on retention for THF and FA and has the lowest impact on 5MTHF degradation. Product formation from 5MTHF and 10 FFA were studied by multiresponse modeling. Both vitamers generated intermediary products that accumulated differently as a function of pH. These results give comprehension and kinetic insights into folate degradation during food processing from the formulation (pH lever) to the process (temperature lever). Practical Applications This article brings new insights into vitamins B9 degradation during cooking. Folate is a group of vitamins, sharing a similar molecular structure while having different bioactivity. The lack of folate in diet can lead to severe health disorder. Their human metabolization and thermic degradation can be influenced by different factors, including their own structure. Therefore, it is of high importance to understand how each form is degraded and to determine the best formulation and process conditions to preserve them. Our work, in model mediums, allowed to identify four folate forms reactivity and degradation (including degradation pathway) in order to give more guidance, and offers an operational tool for manufacturer to determine the potential retention of folates as a function of pH, temperature and vitamer composition.