Investigations of the connection between structure and ice recrystallization inhibition activity of carrageenans

• Applicant: Professor Dr. Daniel Wefers
• Subject Area: Food Chemistry
• Term: from 2018 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 413076269

Ice recrystallization is one of the main reasons for quality losses during storage of frozen goods. This is mostly relevant for frozen food, but also for other processes such as storage of cells and organs. Therefore, the use of substances which inhibit ice recrystallization is of great interest. It has already been demonstrated that kappa-carrageenan, a hydrocolloid which is commonly used for gelation, is able to suppress ice recrystallization. However, previous investigations were carried out by using structurally uncharacterized kappa-carrageenan samples. Therefore, nothing is known about the responsible structural elements and the inhibition of ice recrystallization by other carrageenan types. Carrageenans are structurally complex polysaccharides from different algae which are often described in a simplified way. Consequently, a detailed structural characterization is necessary to derive structure-function relationships. To investigate the influence of single structural elements and to obtain comparable conditions during the determination of the ice recrystallization inhibition activity, it is also necessary to chemically and enzymatically modify carrageenans. The aim of this study is to systematically investigate the recrystallization inhibition activity of structurally different carrageenans. Initially, the polysaccharide structures of various commercially available carrageenans will be characterized by using modern chromatographic and spectroscopic methods. Based on the results, different carrageenan samples are selected for a modification of naturally occurring structural elements and for a modification of the cations present in the carrageenan preparations. In addition, recombinant carrageenan degrading enzymes will be isolated and characterized for a more detailed investigation of structurally complex carrageenans and to selectively modify single structural elements. Eventually the ice recrystallization inhibition activity of all modified carrageenan samples will be investigated in an established model system under identical conditions.The goal of these investigations is to understand the ice recrystallization inhibition activity based on the carrageenan structures. It is expected that the insights into the molecular mechanism will contribute to the understanding of the ice recrystallization inhibition mechanism of other compounds. In addition, the structure-function relationship will allow for a specific use of carrageenans to inhibit ice recrystallization and an improvement of carrageenan manufacturing processes to obtain carrageenans with a high ice recrystallization inhibition activity.

• DFG Programme: Research Grants