## 1 Introduction  
It is estimated that 40-50% of the global fruit and vegetable production is lost or wasted along the supply chain, which is approximately half of the total amount of food waste [1, 2]. This leads not only to wastage of resources and corresponding avoidable greenhouse gas emissions, but also creates huge economic losses [1, 2]. Therefore, reducing the amount of food wasted and lost along the supply chain is of major importance regarding sustainability and economical aspects [1]. There is no single reason for the high losses in the fresh fruit and vegetable sector, but several characteristics make these products particularly prone to wastage. They are highly perishable with shelf life and postharvest quality being strongly influenced by the environmental conditions during storage and transportation [3]. Furthermore, the seasonality of many fruits and vegetables can lead to discrepancies between the availability and the market situation, causing product losses [4]. An additional aspect is the increasing consumer demand for the highest product quality [3]. Together with rising quality standards enforced by retail, this results in high losses of less aesthetically perfect products, especially when marketing alternatives are lacking [1, 4]. Both the postharvest quality retention and the shelf life of fresh fruit and vegetables are influenced by a range of ambient parameters such as temperature, relative humidity (RH), gas atmosphere and shock or vibration [5; 6]. Monitoring and controlling these parameters during storage and distribution contributes to optimized product qualities and reduction of losses in the respective supply chains [5]. Combining the product's temperature history with shelf life models allows predictive shelf life calculations and improved logistic decisions [7; 8]. A common way for ambient parameter tracking is using respective sensor technology. Various solutions have been developed in recent years [6]. With the progress of the IoT, monitoring systems with wireless real-time data exchange between numerous system components become possible [9; 10]. This is a huge advantage over most conventional systems such as dataloggers, graphical temperature recorders, time-temperature integrators and smart labels, which require physical interaction with the device for data extraction [11]. [PERSON] et al. [12] proposed an IoT-based monitoring system, including layers for sensing (sensing layer), transmitting and processing (network layer) and management of data (application layer). The corresponding technologies are emerging and partly already commercially available. However, despite the rapid technological development and the potential for reducing food loss and waste, the implementation of IoT-based monitoring systems is still facing unsolved challenges. Ambient parameter tracking using IoT technologies has been investigated in various studies [13; 14; 15], but the corresponding detailed concepts on data processing and cross-chain implementation are missing. Fruit and vegetables are a complex product group with various freshness and quality characteristics. Depending on the product and its spoilage kinetics, different ambient parameters are important and useful to measure. This leads to a broad range of monitoring requirements for fruit and vegetables on the one hand. On the other hand, a variety of IoT-based technologies is available, but there are currently no generic guidelines that help actors to decide which technology fits best for their specific supply chains. The central objective of this review is to give an overview of IoT-enabled sensor and communication technology for monitoring ambient parameters in relation to the specific quality and spoilage characteristics of fresh fruit and vegetables. Current technological solutions were reviewed for their potential regarding useful applications in supply chains of fresh plant-based produce.