Statement of the Prolamin Working Group on the Determination of Gluten in Fermented Foods Containing Partially Hydrolyzed Gluten - Scherf, Katharina Anne; Catassi, Carlo; Chirdo, Fernando G.; Ciclitira, Paul J.; Feighery, Conleth Francis; Gianfrani, Carmen; Koning, Frits; Lundin, Knut E. A.; Masci, Stefania; Schuppan, Detlef; Smulders, Marinus J. M.; Tranquet, Olivier; et al. (Frontiers in Nutrition, 2021)