Mass cooking facilities, such as school lunch centers and central kitchens, must prepare hundreds to thousands of meals within a limited time. Recently, these workplaces have faced a severe labor shortage.

As a result, it has become difficult to maintain efficient and hygienic operations with a limited number of staffs. To solve this problem, it is essential to create a cooking schedule that optimizes worker allocation, task order, and time distribution.

In mass cooking facilities, sanitation control based on HACCP is mandatory. HACCP-based control requires the prevention of food contamination. It also requires the management of work areas in accordance with hygiene standards. Manual preparation of a schedule that satisfies these hygiene requirements requires expertise and time.

The aim of this study is to propose an optimization model that automatically creates cooking schedules satisfying hygiene requirements and achieve efficient operations. The model considers task precedence, staff working hours, and minimization of sanitation risks caused by worker movement.

The scheduling problem is modeled as a combinatorial optimization problem. The objective function of the problem is the weighted sum of makespan and task start times. An exact optimal solution of the problem is obtained using a mathematical optimization solver. Numerical experiments are conducted using real data provided by a contract food service cooperation in Japan. The results show the proposed method shortens schedule creation time in comparison with manual creation. An expert of schedule creation in the company evaluated the schedules created by the proposed method as comparable to those created manually.

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Mr. Yuki Ozaki