In this paper, we focus on the labour-intensive human cooking process and analyze cooking recipes using systems engineering techniques. The purpose of this is paper to help analyze the impact of specifying cooking recipes from the perspective of work instructions on the reproducibility and development of food. Specifically, we use as an example the recipe for “Fuhafuha Tofu,” which appears in number 21 of the cookbook “Tofu Hyakuchin” published in the Edo period between 1603 and 1868 in Japan. We focus on the ambiguity of the description method in this cooking recipe. First, we extract expressions that are described as explicit textual information in the cooking recipe. Next, we analyze the information containing the ambiguity described in the cooking recipe and the information that is not directly described. These are assumed to be information containing ambiguities that can be inferred from the context even without being instructed when the operator performs the cooking task. We will take the specifications of modern cooking recipes and compare and analyze how they are written from the perspective of work instructions.