Stability and Collapse of cell wall containing systems
In accordance with the UN Sustainable development goals and Paris Agreement, an increase in the consumption of plant based foods is called for to meet the goals of a healthy diet in a sustainable food production system. Incorporation of plant based foods as ingredients is a good way to increase the consumer intake of these foods. However in certain dry ingredients like pectin and polymer mixtures, the stability is a concern as they are prone to collapse phenomena. Moreover, it is essential to link stability of foods to their processing and storage conditions. The objective of this PhD is to determine the stability of ingredients and food systems by using the concept of glass transition, which can help in overcoming the limitation of water activity based stability concept. The first part is focused on determining the biochemical and enzymatic stability of pectin in relation to temperature and moisture content. Change in functionality such as the rheological properties is also linked to its stability. The second part of the study focuses on functionalization of vegetable-based cell wall containing systems and studying the collapse phenomena during storage of the dried cell wall material. The presence of multiple components (cellulose, hemicellulose and pectin) differentiates it from the single polymer (pectin) used in the first study. The final objective is to study the stability of beans which have been functionalized to reduce the cooking time for consumers. Beans are chosen as an example of a heterogeneous and structured food system with components exhibiting multiple states. Stability is measured by different (bio-)chemical reactions taking place in different substructures of the bean, and by evaluation of the loss of functionality during storage. Also a comparison of different instrumental methods to measure glass transition such as Differential Scanning Calorimeter, Thermal Rheological/Mechanical analysis and kinetics of (bio-)chemical reaction shall be evaluated.