## 4 Discussion and Main Conclusions  
In the first part of this study, an overview of the traceability systems for fresh produce supply chains was presented. This field is particularly challenging, since fresh produce  
Figure 4: Schematic of IoT implementation using LoRa network. has short shelf lives and is vulnerable to environmental conditions. For the purpose of securing food safety, traceability has become a consumer driven demand in modern agriculture. In essence, traceability enables consumers to track back the fresh products to the whole supply chain providing useful information concerning the transportation, handling, processing and the packaging reaching up to the producer level. Taking into account the recent developments of sensing technologies and IoT systems, an opportunity is given to trace the fresh produce further, reaching the field level, providing information in relation to the growing conditions and practices and much more. Moreover, traceability provides the possibility to companies for sales tracking and discount planning, as well as tracing batch input materials and recalling across the supply chain, thus, improving their competitiveness. However, owing to the complexity of fresh produce traceability, a large volume of reliable data has to be collected, while information management, interoperability and data sharing constitute key challenges to be addressed. Towards that direction, IoT systems have been incorporated in traceability systems ranging from sensors for gathering important information to RFID, QR codes, WSN and cloud technologies. Despite the increasing interest in traceability systems worldwide and the advance in IoT technologies, the available traceability systems on market are relatively scarce. Besides, they usually cover a limited part of the supply chain and do not rely on open interoperability standards. In contrast, the AgroTRACE system, proposed in this study, offers a solution for fresh produce traceability based on a modular approach that uses open and transparent standards enabling interoperability. The innovative approach relies on the integration of three elements, namely the event capturing and IoT application platform, the transaction support and information management system, and the data mapping system. Moreover, traceability capabilities go beyond the farm-to-shelf route and cover the farm-to-shelf-to-farm route as well as waste management. For the realization of the smooth operation of AgroTRACE traceability system, a plethora of Information and Communications Technologies (ICT) are used: e.g., visual reading through smart devices (RFID and beacon technologies), MQTT and XMPP protocols for supporting real-time communication even at remote locations, a LoRaWAN network for inter-device communication, and GS1 interface standards (GDSN, EDI, GTIN, GLN, SSCC and EPCIS) for interoperability and data sharing. In a nutshell, traceability has become a perquisite of improving food quality and safety, recall efficiency, information transparency, security and trust in transactions. However, many challenges need to be overcome. In this context, the proposed AgroTRACE traceability system, by following a novel system architecture and utilizing the most recent technological advances, can contribute to more efficient operation of the entire fresh produce supply chain. Overall, by focusing on the interoperability and offering user-friendly and open access IoT services, AgroTRACE aims to bridge the gap in fresh produce traceability and bring added value to the products. Conceptualization, A.C.T., L.B. and D.K. ; methodology, A.C.T., L.B. and D.K. ; validation, A.C.T., L.B. and D.K. ; formal analysis, A.C.T. and L.B. ; resources, D.B. ; data curation, A.C.T., L.B., D.K. and N.T. ; writing--original draft preparation, A.C.T. and L.B. ; writing--review and editing, A.C.T., L.B. and D.K. ; visualization, L.B. ; supervision, A.C.T. and D.K. ; project administration, D.K. ; funding acquisition, D.B. and N.T. All authors have read and agreed to the published version of the manuscript.