title: Effect of heat on phycoerythrin fluorescence: Influence of thermal exposure on the fluorescence emission of R-phycoerythrin.
abstract: The goal of this work was to measure and model the effect of thermal exposure on the fluorescence emission of R-phycoerythrin (R-PE). The long-term objective of our work is to assess the feasibility of encapsulating R-PE for use as the critical component of a time-temperature integrator (TTI) for ascertaining the degree of inactivation of food pathogens such as Salmonella. In this article we present a study to measure and model the thermally induced fluorescence emission decay of R-PE in several isothermal experiments. We used the isothermal data to determine the kinetic parameters, based on a general n(th) order reaction, and evaluated the utility of the resulting model by using it to predict R-PE fluorescence emission decay for several nonisothermal experiments based on published USDA safe harbor guidelines for cooked beef products. The transient experiments were conducted over the same temperature range used in the isothermal study. Very good agreement was obtained between theory and experiment at temperatures of 62.8 degrees C and above, although the model slightly underpredicted the extent of fluorescence emission decay at 60 degrees C. Our results indicate that R-PE fluorescence emission decay kinetics is well behaved and that the protein is a strong candidate for use as a time-temperature integrator.
authors.affiliation: Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan 48824, USA.
authors.forename: S
authors.initials: S
authors.lastname: Vaidya
authors.forename: A
authors.initials: A
authors.lastname: Orta-Ramirez
authors.forename: D M
authors.initials: DM
authors.lastname: Smith
authors.forename: R Y
authors.initials: RY
authors.lastname: Ofoli
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D003198:Computer Simulation; D004307:Dose-Response Relationship, Radiation; D005453:Fluorescence; D006358:Hot Temperature; D007700:Kinetics; D008956:Models, Chemical; D010799:Phycoerythrin / Q000737:chemistry* / Q000528:radiation effects*; D011829:Radiation Dosage; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000295:instrumentation / Q000379:methods*; D013696:Temperature; D013817:Thermography / Q000295:instrumentation / Q000379:methods*
chemical_list: D010799:Phycoerythrin