The Phase Space as a New Representation of the Dynamical Behaviour of Temperature and Enthalpy in a Reefer monitored with a Multidistributed Sensors Network

The study of temperature gradients in cold stores and containers is a critical issue in the food industry for the quality assurance of products during transport, as well as forminimizing losses. The objective of this work is to develop a new methodology of data analysis based on phase space graphs of temperature and enthalpy, collected by means of multidistributed, low cost and autonomous wireless sensors and loggers. A transoceanic refrigerated transport of lemons in a reefer container ship from Montevideo (Uruguay) to Cartagena (Spain) was monitored with a network of 39 semi-passive TurboTag RFID loggers and 13 i-button loggers. Transport included intermodal transit from transoceanic to short shipping vessels and a truck trip. Data analysis is carried out using qualitative phase diagrams computed on the basis of Takens?Ruelle reconstruction of attractors. Fruit stress is quantified in terms of the phase diagram area which characterizes the cyclic behaviour of temperature. Areas within the enthalpy phase diagram computed for the short sea shipping transport were 5 times higher than those computed for the long sea shipping, with coefficients of variation above 100% for both periods. This new methodology for data analysis highlights the significant heterogeneity of thermohygrometric conditions at different locations in the container

THE ADSORPTION INVITRO OF PURIFIED SALIVARY PROTEINS ON BOVINE DENTAL ENAMEL

The adsorption of proteins isolated from human submandibular saliva was studied on intact enamel surfaces and on enamel powder. All proteins adsorbed in a monolayer, in a single-step adsorption mechanism, suggesting that some of the molecules have a flexible (random coil) structure. The proteins did not release measurable amounts of ions from the adherent liquid layer during adsorption, in contrast to previous findings on the adsorption of several homopolypeptides (Juriaanse et al., J. Colloid Interface Sci.76, 212–220; 1980). Salivary phosphoproteins are more firmly bound to enamel surfaces than are non-phosphorylated proteins, which is due to an exchange reaction in which protein phosphate groups replace surface phosphates in the enamel mineral. In the model used for pellicle maturation, the enamelpellicle interface was slowly saturated with phosphoproteins which displaced non-phosphorylated proteins from the surface