Within the framework of the European project EcoBioCap (ECOefficient BIOdegradable Composite Advanced Packaging), aiming at conceiving the next generation of food packagings, we introduce an argumentation-based tool for management of conflicting viewpoints between preferences expressed by the involved parties (food and packaging industries, health and waste management authorities, consumers, etc.). In this paper we recall briefly the principles underlying the reasoning process, and we detail the main functionalities and the architecture of the argumentation tool covering the overall reasoning steps starting from formal representation of text arguments and ending by extraction of justified preferences. Finally, we detail its operational functioning through a real life case study to determine the justifiable choices between recyclable, compostable and biodegradable packaging materials based on stakeholders’ arguments.