Rosenfeld, Zachariah Joseph. Sepher Yoseph Tikvah [on the permissibility of using machine-made Matzoth on Passover]. With an appendix regarding Rosenfeld’s inquiries to the Department of Zoology at Washington University and the Smithsonian Institution

The introduction of machine-made matzoth in the middle of the 19th century sparked an extended halachic debate as to whether the machine process caused fermentation. Did milling by heavy machinery cause wheat to exude a moisture which might bring about fermantation and, specifically, could small pieces of dough adhering to the machinery have the same effect