Reiner Jedermann

Reducing food losses by intelligent food logistics

The need to feed an ever-increasing world population makes it obligatory to reduce the millions of tons of avoidable perishable waste along the food supply chain. A considerable share of these losses is caused by non-optimal cold chain processes and management. This Theme Issue focuses on technologies, models and applications to monitor changes in the product shelf life, defined as the time remaining until the quality of a food product drops below an acceptance limit, and to plan successive chain processes and logistics accordingly to uncover and prevent invisible or latent losses in product quality, especially following the first-expired-first-out strategy for optimized matching between the remaining shelf life and the expected transport duration. This introductory article summarizes the key findings of this Theme Issue, which brings together research study results from around the world to promote intelligent food logistics. The articles include three case studies on the cold chain for berries, bananas and meat and an overview of different post-harvest treatments. Further contributions focus on the required technical solutions, such as the wireless sensor and communication system for remote quality supervision, gas sensors to detect ethylene as an indicator of unwanted ripening and volatile components to indicate mould infections. The final section of this introduction discusses how improvements in food quality can be targeted by strategic changes in the food chain.

The “Intelligent Container”—A Cognitive Sensor Network for Transport Management

The “Intelligent Container” is a sensor network used for the management of logistic processes, especially for perishable goods such as fruit and vegetables. The system measures relevant parameters such as temperature and humidity. The concept of “cognitive systems” provides an adequate description of the complex supervision tasks and sensor data handling. The cognitive system can make use of several algorithms in order to estimate temperature related quality losses, detect malfunctioning sensors, and to control the sensor density and measurement intervals. Based on sensor data, knowledge about the goods, their history and the context, decentralized decision making is realized by decision support tools. The amount of communication between the container and the headquarters of the logistic company is reduced, while at the same time the quality of the process control is enhanced. The system is also capable of self-evaluation using plausibility checking of the sensor data.

Semi-passive RFID and beyond: steps towards automated quality tracing in the food chain

Precise temperature monitoring is the major precondition to supervise quality losses within the transport chain for fresh products. Different types of miniaturised data loggers with electrical and semi-passive RFID interface were compared and applied to record spatial temperature profiles for typical transport situations. The resulting effects of the found temperature variations were evaluated by mathematical shelf-life modelling. Wireless sensor networks with active communication offer permanent access to sensor condition but entail higher system costs. Different approaches for implementation of integrated quality assessment will be discussed using a concept for shelf-life calculation on RFID-level and the intelligent container as demonstrator for an automated transport supervision system.

The benefits of embedded intelligence: tasks and applications for ubiquitous computing in logistics

The concept of autonomous cooperating processes is an approach to solve complex logistical planning tasks by representing each object in the transport chain by a separate independent software unit. In general, these software units or agents are applied in a server network. Technologies from the field of the Internet of Things like wireless communication and RFID enable that software execution can be shifted to deeper system layers, even at the level of single freight items. This article examines the ancillary conditions and consequences of this shift. It focuses on whether the introduction of the intelligent parcel or vehicle is advantageous compared to server based planning. The second half of this article describes transport logistic examples for networks of autonomous objects with embedded intelligence.

Intelligent Containers and Sensor Networks Approaches to apply Autonomous Cooperation on Systems with limited Resources

RFIDs, sensor networks and low-power microcontrollers are increasingly applied in logistics. They are characterized by restrictions on calculation power, communication range and battery lifetime. In this article we consider how these new technologies can be utilized for autonomous cooperation and how these processes could be realized on systems with limited resources.

Communication techniques and challenges for wireless food quality monitoring

Remote measurement of product core temperature is an important prerequisite to improve the cool chain of food products and reduce losses. This paper examines and shows possible solutions to technical challenges that still hinder practical applications of wireless sensor networks in the field of food transport supervision. The high signal attenuation by water-containing products limits the communication range to less than 0.5 m for the commonly used 2.4 GHz radio chips. By theoretical analysis of the dependency of signal attenuation on the operating frequency, we show that the signal attenuation can be largely reduced by the use of 433 MHz or 866 MHz devices, but forwarding of messages over multiple hops inside a sensor network is mostly unavoidable to guarantee full coverage of a packed container. Communication protocols have to provide compatibility with widely accepted standards for integration into the global Internet, which has been achieved by programming an implementation of the constrained application protocol for wireless sensor nodes and integrating into IPv6-based networks. The sensors battery lifetime can be extended by optimizing communication protocols and by in-network pre-processing of the sensor data. The feasibility of remote freight supervision was demonstrated by our full-scale ‘Intelligent Container’ prototype.

Remote quality monitoring in the banana chain

Quality problems occurring during or after sea transportation of bananas in refrigerated containers are mainly caused by insufficient cooling and non-optimal atmospheric conditions, but also by the heat generated by respiration activity. Tools to measure and evaluate these effects can largely help to reduce losses along the banana supply chain. The presented green life model provides a tool to predict the effect of deviating temperature, relative humidity, and CO2 and O2 gas concentrations on the storage stability of bananas. A second thermal model allows evaluation of the cooling efficiency, the effect of changes in packaging and stowage and the amount of respiration heat from the measured temperature curves. Spontaneous ripening causes higher respiration heat and CO2 production rate. The resulting risk for creation of hot spots increases in positions in which the respiration heat exceeds the available cooling capacity. In case studies on the transport of bananas from Costa Rica to Europe, we validated the models and showed how they can be applied to generate automated warning messages for containers with reduced banana green life or with temperature problems and also for remote monitoring of the ripening process inside the container.

Testing network protocols and signal attenuation in packed food transports

Two sensor network protocols for the monitoring of packed food products were tested in different sea containers. The packet rate and the signal strength of all sensor-to-sensor links were recorded in the flash memory of the sensor nodes. The performance of the two protocols was compared and protocol improvements were tested by simulation based on this data. The high signal attenuation by water-containing products was identified as the major problem. One of the two tested protocols was newly developed with a focus on low energy consumption. A simplified link estimator, which required only a minimum number of control messages, detects the correct routing in most cases.

Logistic applications with wireless sensor networks

Wireless Sensor Networks have been deployed for environmental monitoring, home automation, and advanced metering application fields among others. Only few examples of monitoring cargo transports by Wireless Sensor Networks have been reported on. The authors have deployed mobile Wireless Sensor Networks in a cargo container on a trans-atlantic cargo vessel as well as on a lorry to monitor the transport conditions inside the container. This submission reports on the experiences gained from those particular deployments and the open research issues for mobile Wireless Sensor Networks for logistics.

The Minimum Number of Sensors --- Interpolation of Spatial Temperature Profiles in Chilled Transports

Wireless sensor networks are an important tool for the supervision of cool chains. Previous research with a high number of measurement points revealed spatial temperature deviations of more than 5 °C in chilled transport, but the number of sensors has to be reduced to an economically useful value for use in regular transport. This paper presents a method to estimate the minimum number of sensors and to compare different sensor positioning strategies. Different methods of interpolating the temperature data of intermediate positions were applied to the experimental data from a delivery truck. The average prediction error for intermediate points was estimated as a function of the number of sensors. The Kriging method, originally developed for the interpolation of geostatistical data, produced the best results.