Zohreh Alipour - School of School of Industrial and Systems Engineering, College of Engineering, University of Tehran, Tehran, Iran
Fariborz Jalai - School of School of Industrial and Systems Engineering, College of Engineering, University of Tehran, Tehran, Iran
Nima Zaerpour - College of Business Administration, California State University San Marcos, US
Ehsan Monabbati - Faculty of Mathematical Sciences, Alzahra University, Tehran, Iran

Recently, fresh food production management has received an increasing attention. In light of perishability, shelf life and freshness improvement are taken into account in such problems. We study the general lot-sizing and scheduling problem in a fresh food production with fixed shelf life under demand uncertainty. In particular, we focus on yogurt production as one the most critical cases in fresh food industry. We developed a deterministic multi-objective mixed-integer linear programming (MILP) model for a multi-product, multi-parallel line, multi-period problem. Furthermore, the first objective function is sum of different cost functions, such as sequence dependent change over cost and time, sequence independent set up cost and time, labor regular and over time cost, and etc. The secondary objective function is freshness function. Also, considering demand uncertainty, we apply scenario-based robust optimization framework using event tree for scenario generation. The weighted sum and -constraint method were applied to get optimal solutions.

General lot sizing and scheduling, freshness, yogurt production, scenario-based robust optimization