Food waste is both an industrial and residential source of pollution, and there has been a great need for food waste reduction. As a preliminary step in this study, waste reduction is quantitatively modeled. This study presents two models based on kinetics: a simple kinetic model and a mass transport-shrinking model. In the simple kinetic model, the smaller is the reaction rate constant ratio k1 , the lower the rate of conversion from the raw material to intermediate products. Accordingly, the total elapsed reaction time becomes shorter. In the mass transport-shrinking model, the smaller is the microbial decomposition resistance versus the liquid mass transfer resistance, the greater is the reduction rate of the radius of spherical waste particles. Results showed that the computed reduction of waste mass in the second model agreed reasonably with that obtained from a few experimantal trials of biodegradation, in which the microbial effect appeared to dominate. All calculations were performed using MATLAB 2020 on PC.