## 2 Review of State-of-Art of Commercial Sensors for Shelf-Life Prediction Used in Transportation  
A market study was carried out to review the technologies offered by different companies worldwide. It focuses on how the equipment controls the commodities during transportation, irrespective of kind of goods, industries, features controlled or transport.  
An analysis of the dataloggers used yielded the following results: the simplest passive communication one is based on time-temperature indicators (TTI) and just controls temperature [31], but it is not the most frequently used because RFID is the most extensive. The Faubel (Faubel & Co. Nachf. GmbH, Melsungen, Germany) company offers a system based on RFID and NFC, but it just controls temperature [32]. NFC communication is used by Marathon Products (Marathon Products, Inc., San Leandro, CA, USA) [33]. The disadvantage of these systems is the dependence on other devices for the manual or low-distance reading process, which avoids the possibility of network sensor reading and the real-time data transferring to proprietary servers for remote access. To avoid these inconveniences, some companies deploy gateway devices able to manage the measuring nodes, allowing for remote sensing and collecting data. This is the case of Secure System (Secure System GmbH, Munich, Germany), which focuses on security and personalized container access control, and recently also controls temperature and humidity [34]; Sensitech (Sensitech, Beverly, MA, USA), which uses a router that receives the information transferred by a RFID sensors network [15]; and OnAsset Intelligence (OnAsset Intelligence, Inc., Irving, TX, USA), which connects its sensor tags by Bluetooth Low Energy (BLE) [35] to a harvesting data-system. With this evolution, these companies offer a flexible tool that allows for wireless measurement at several points simultaneously. In the last few years, other companies have promoted the use of devices connected via LoRa as an improvement. However, although they allow for wireless communications between measurement points, they need routers or gateways to send the data to the Internet [36; 37; 38; 39]. ORBCOMM [40] (ORBCOMM Networks LLC, Rochelle Park, NJ, USA) and Aeris (Aeris Communications, Inc., San Jose, CA, USA) [41] implement their connected devices directly into the microprocessor installed into the refrigerator container to register the temperature readings to use their cloud connectivity.  
A synergy between the connection by BLE or LoRa and the communication using GSM is made by Roambee (Roambee Corporation, Santa Clara, CA, USA) [42], Swiftsensor (Swift Sensors, Inc., Austin, TX, USA) [43] or JRI (JRI, Fesches le Chatel, France) [44], whose systems send the registered data to a user interface. Laird Connectivity (Laird Connectivity, Akron, OH, USA) [45] has replaced BLE with NB and LTE. Meanwhile, HyperTech (Hyper-Tech Systems, Petach Tikva, Israel) [46] offers sensors based on Zigbee wireless devices, in the same way as hOTron (hOTron Gateway and application, Ashoka Nagar, Maharashtra) [47], which includes with in-built GNSS module to track the vehicle position. Other companies including SenseAware from FedEx (FedEx Corporate Services, Inc., Memphis, TN, USA) [48] or TagBox (TagBox Solutions Private Limited, Bengaluru, India) [49] prefer to work with wireless devices that use Wi-Fi and GSM technologies for communication facilities.  
As an evolution, some companies design devices that work simultaneously as a sensor and router collecting and send the data using just GSM [50; 51; 52; 53].