title: Direct measurement of the thermal hysteresis of antifreeze proteins (AFPs) using sonocrystallization.
abstract: Antifreeze proteins (AFPs) are of great importance for applications in cryomedicine or the food industry. They are frequently used to lower the freezing point by preventing the growth of larger ice crystals; thus, it is paramount to determine their thermal hysteretic characteristics. However, the experimental analysis of the thermal hysteresis-an effect that is characteristic for AFPs-remains a challenging process. An easy-to-use test method for measuring the thermal hysteresis of AFPs was developed and tested with the type III AFPs. Traditional methods that have been used until now have their disadvantages and limitations. The new measurement method described in this paper allows detection of the complete cooling, freezing, heating, and melting process in a single measurement. This makes it possible to directly determine the thermal hysteresis as a functional effect of the antifreeze proteins. Measurements of the thermal hysteresis were performed by applying ultrasound to initiate the crystallization process of the antifreeze protein solution. This ultrasound technique also allows a crystallization process to be performed at defined temperature. The demonstrated results were highly reproducible and could be clearly read off the measurement curves. As a future perspective, this enables the design of automatic test devices that can be also miniaturized.
authors.affiliation: Fraunhofer Institute for Manufacturing Technology and Advanced Materials, Bremen, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Gaede-Koehler
authors.forename: Alexej
authors.initials: A
authors.lastname: Kreider
authors.forename: Peter
authors.initials: P
authors.lastname: Canfield
authors.forename: Malte
authors.initials: M
authors.lastname: Kleemeier
authors.forename: Ingo
authors.initials: I
authors.lastname: Grunwald
mesh_terms: D000818:Animals; D021301:Antifreeze Proteins / Q000032:analysis* / Q000737:chemistry*; D003080:Cold Temperature; D003460:Crystallization; D006358:Hot Temperature; D010473:Perciformes / Q000378:metabolism*; D044367:Phase Transition; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D021301:Antifreeze Proteins