This paper proposes a new food-evaluation technique based on biological information of the human body. Innovating a new food evaluation technique based on biological information can allow us to develop high-valued food products on the occasion of food design. We particularly focus on a small intestine and assume that the digestive activity varies depending on an individual constitution, health condition and compatibility between an individual and a food. This method can track digests in a small intestine and determine their status by using an ultrasound B-mode movie. We acquire peristaltic activity of a small intestine using frame subtraction method and determine their status using optical flow.This allows quantifying peristaltic activity of a small intestine based on tracking of digests in an abdominal B-mode movie.