# Monitoring Perishable Commodities Using Cellular IoT:
## 1 Introduction  
According to the Food and Agriculture Organization (FAO), roughly one-third of food produced for human consumption is wasted annually, which corresponds to about 1.3 billion tons of food waste per year, while there are up to 783 million people around the world facing hunger [1; 2; 3]. Target 12.3 of the Sustainable Development Goals (SDGs) aims to halve food waste per capita worldwide, both at retail and consumption levels, with one of the important factors to consider being to reduce food losses along production and supply chains [4]. These losses can occur during the storage, transportation and processing of the commodities. Perishable products, such as fruits and vegetables, need to be transported from the agricultural production and harvest to the wholesaler or retailer, where the product is stored until it is consumed [3]. In general, this transportation lasts several days until it reaches the destination [5], especially if the products are to be exported. In order to keep the quality of the transported perishable products as high as possible, suitable environmental conditions are essential [6; 7; 8]. Important factors to bear in mind aretemperature, relative humidity, luminosity, gas concentrations such as oxygen (O\({}_{2}\)), carbon dioxide (CO\({}_{2}\)) or ethylene (C\({}_{2}\)H\({}_{4}\)) and vibrations, which affect the quality degradation of the products. Therefore, they need to be measured and controlled to achieve optimal preservation conditions during the postharvest supply chain [9; 10; 11; 12; 13; 14]. Temperature is the most significant factor in order to extend the shelf life of products, so it is important to keep it within certain boundaries during the postharvest stages [9; 15]. Transporting or storing perishable products in environments outside of these temperature limits encourages the growth of microorganisms that spoil food [16]. Related to this, according to several mathematical models that have been developed, the data on the evolution of the temperature to which the products are exposed allow for estimations of their quality losses, as well as predicting their shelf life when their quality falls below high-quality standards and is no longer microbiologically safe [17; 18; 19; 20]. For monitoring the most relevant environmental parameters in food quality losses during transportation and storage, new technologies have been employed, which allow the use of dataloggers to record these parameters [21; 22; 23; 24; 25; 26]. On the one hand, this recording can be done passively, saving data locally and without allowing real-time communication, using technologies such as RFID or USB communication. On the other hand, it can also be done using Internet of Things (IoT) technology, which allows devices to use wireless communication, such as Bluetooth or Zigbee, to transmit data to the Internet in real time, allowing the construction of wireless sensor networks (WSN) [27; 28; 29; 30; 31]. Legislation regulates the use of temperature recorders and thermometers for the transport, storage, distribution and control of products at controlled temperatures [32]. Hence, thermographs and passive devices with USB are used on most occasions. However, these passive devices do not allow the operator to know in advance (before the merchandise arrives at retail) what the transport or storage conditions have been, which prevents the operator from making adequate logistical decisions to minimize losses in the event of bad conditions. Real-time knowledge of the conditions of perishable products allows, on the one hand, to elaborate and train shelf-life models using fixed climatic cameras as a digital twin using real-time data and, on the other hand, to use the information estimated by the models to make decisions on the destination of the products by diverting them to markets with higher turnover in case of shelf-life decrease. The most relevant devices to focus on are IoT devices.