Multi-objective optimization based on the utopian point method applied to a case study of osmotic dehydration of plums and its storage

Abstract

In this study, authors present the results of multi-objective optimization of parameters of osmotic dehydration of plum and its storage conditions. Multi-objective optimization is a method of multiple criteria decision making involving more than one objective function to be optimized simultaneously. The objective functions are conflicting and an infinite number of Pareto optimal solutions are possible. A solution is Pareto optimal if none of the objective functions can be improved in value without degrading some of the other objective values. All Pareto optimal solutions are considered equally good, the choice is subjective. To limit subjectivism the Utopian point method and Multidimensional Euclidean metrics was applied. The idea is to minimize the distance between the non-existing Utopian solution and Pareto-optimal solutions. This approach is offered in relation to the cost of osmotic solution, time of dehydration process, and duration of storage by considering the following factors: content of dry mass, reducing sugars, and extract, as well as the amount leak after thawing. Authors made the choice of minimizing cost with simultaneous maximization of quality of the product. Pareto-optimal solutions were obtained with the use of MATLAB program. Furthermore, the method of multidimensional Euclidean preferences was applied to find the set of best parameters for the production process. Two sets of results were obtained. First is the set of optimal process parameters is in relation to cost minimizing: concentration of an osmotic solution: 0.55%; time of osmotic draining:, 1 h 42 min; time of the cold storage: 6 months; and the method of thawing: microwave. Second set is focused on quality and process parameters are: the concentration of an osmotic solution: 0.65%; time of osmotic draining:3 h; time of the cold storage: 5 months and 21 days; method of thawing: microwave.