Active Transponder Technology in the Post-harvest Chain for Fruits and Vegetables F resh fruits and vegetables are limited in shelf life after harvest even under optimal storage conditions. Higher temperatures accelerate the loss of important ingredients. Lower air humidity and strong air current lead to undesired wilting. High air humidity in connection with high temperature support microbial growth and thus cause faster deterioration of the product. Main interest of the actors along the

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... rvest chain from the producer to the consumer is therefore to know, at which stage (producer, transport, wholesale, transport, retail) important losses arise, so that effective counter measures can be taken. The demand for comprehensive traceability along the value-added chain is growing, especially within the particular sensitive segment of food production. Temperature-time information for quality control To examine relevant process cycles small technological units have been available for a short time, which can be fixed on the packaging. Active transponders, which have ap-prox. the dimensions of a credit card, measure temperatures in selectable intervals and store the obtained data. Similarly to price scanner systems additional information about the product (e.g. origin, harvest date etc..) can be saved on the transponder card by certain write/read units. Active transponders operate like complete, simply arranged data loggers with analogue input for temperature measurement. Additionally, radio wave technology (RFID, Radio frequency identification) allows non-contact transmission, i.e. writing and reading, and storage of user and produce specific data on a data memory. While the required energy for data transmission is generated from radio waves of the write/read unit via antennas, the energy for internal processes on the sensor card (in-cluding temperature measurement) is provided by a transponder integrated paper battery. The economic lifetime of the battery is determined by the specific measuring requi-Capacity features and operation criteria of active transponders for the process control of fruits and vegetables are discussed here. Such systems measure the thermal stress on the harvested products and are simultaneously a medium for transmitting the information along the post-harvest chain. Correspondingly diverse possibilities for quality safeguarding of high-value fruit and vegetables arise. Basically detailed consumer information, as well as data on traceability can be provided.