I want to analyse the in vitro digestibility assay of starch. I have downloaded many papers explaining the procedures of in vitro digestibility assay but the protocols were different from paper to paper. Moreover I have also come across the term "free glucose" and "total glucose" in the digestibility assay protocol. Unfortunately, I failed to understand the concept of these two terms. Can anyone help me in solving these problems and in determining the digestibility assay of starch sample?