Shelf life of fresh fruits and vegetables is greatly influenced by environmental conditions. Increasing temperature usually results in accelerated loss of quality and shelf-life reduction, which is not physically visible until too late in the supply chain to adjust logistics to match shelf life. A blackberry study showed that temperatures inside pallets varied significantly and 57% of the berries arriving at the packinghouse did not have enough remaining shelf life for the longest supply routes. Yet, the advanced shelf-life loss was not physically visible. Some of those pallets would be sent on longer supply routes than necessary, creating avoidable waste. Other studies showed that variable pre-cooling at the centre of pallets resulted in physically invisible uneven shelf life. We have shown that using simple temperature measurements much waste can be avoided using ‘first expiring first out’. Results from our studies showed that shelf-life prediction should not be based on a single quality factor as, depending on the temperature history, the quality attribute that limits shelf life may vary. Finally, methods to use air temperature to predict product temperature for highest shelf-life prediction accuracy in the absence of individual sensors for each monitored product have been developed. Our results show a significant reduction of up to 98% in the root-mean-square-error difference between the product temperature and air temperature when advanced estimation methods are used.

No abstract

AcknowledgementsAt the beginning of this document I would like to gratefully acknowledge the help and collaboration received for those persons and organizations that have made possible the development of my PhD Thesis, and specially:A mi tutor, el profesor Luis Ruiz García, por creer en mi trabajo, no dejar que me tuerza, y recordarme que todo tiene solución.A la Universidad Politécnica de Madrid, pues estoy muy agradecido por todos los conocimientos que he adquirido estudiando y trabajando en ella. Y al Departamento de Ingeniería Agroforestal, porque he aprendido lecciones de valor incalculable de las personas que lo componen.A todos y cada uno de los miembros del grupo de investigación LPF Tagralia, donde comencé mi carrera en la cadena del frío. Fueron unos pasos muy importantes que hicieron que me decidiese por este camino profesional. A las profesoras Pilar Barreiro, Margarita Ruiz Altisent y Belén Diezma, las tres directoras del grupo desde que obtuve mi primera beca, siempre confiaron en mi trabajo. PhD Thesis Ricardo Badía Melis AcknowledgementsAl Centro Nacional de Investigaciones Metalúrgicas (CENIM-CSIC), por el apoyo recibido, especialmente a José Ignacio Robla Villalba y a Javier García Hierro.To Jean Pierre Emond, from the Department of Agricultural and BiologicalEngineering in the University of Florida, for being a tutor in life, the professional that I would like to become, he inspired many of the work here.To Cecilia Nunes, from the Department of Cell Biology, Microbiology and Molecular Biology in the University of South Florida, for being my AmericanPortuguese mom, for helping me so much when I was away from home.To Ismail Uysal from the Electrical Engineering Department at University of South Florida, because we always understood each other very well, he also relied a lot in my work, and that made me trust in what I was doing.To Ultan Mc Carthy, thanks for the immense and essential work of revision of English, it has really saved me more than once. Thanks for the hundreds of liters of coffee from Starbucks and sandwiches from Subway.A Pedro Hoyos, por valorarme, y por su enorme esfuerzo para conseguir material imprescindible para la tesis. Él contactó con los agricultores de Villa del Prado (Madrid) los cuales nos dieron los frutos (pepinos) para los experimentos; también con la cooperativa GLUS-I de Cuéllar (Segovia) los cuales nos dieron las raíces (zanahorias), y finalmente al Centro deInvestigación Agraria de Marchamalo (Guadalajara), que nos proporcionó las hojas (acelgas). A todos ellos, les agradezco su inestimable ayuda.A Virginia Díaz, José Luis Pellón González, y al Laboratorio deTermotecnia en la ETSIAAB. Su ayuda fue indispensable para realizar los experimentos en sus cámaras frigoríficas.To Ryan and Jen, part of my family in the US, now I understand better the American culture… I think so. PhD Thesis Ricardo Badía Melis AcknowledgementsTo my people in Florida because they made me feel at home at all times, both the Spaniards and the Americans. I learned to work in a foreign countr...