Importance of intrinsic properties of dense caseinate dispersions for structure formation
Manski, J.M. ; Riemsdijk, L.E. van; Goot, A.J. van der; Boom, R.M. - \ 2007
Biomacromolecules 8 (2007)11. - ISSN 1525-7797 - p. 3540 - 3547.
induced phase-separation - wormlike micelles - shear-flow - light-scattering - suspensions - particles - milk - instabilities - aggregation - alignment
Rheological measurements of dense calcium caseinate and sodium caseinate dispersions (15%) provided insight into the factors determining shear-induced structure formation in caseinates. Calcium caseinate at a sufficiently high concentration (30%) was shown to form highly anisotropic structures during shearing and concurrent enzymatic cross-linking. In contrast, sodium caseinate formed isotropic structures using similar processing conditions. The main difference between the two types of caseinates is the counterion present, and as a consequence, the size of structural elements and their interactions. The rheological behavior of calcium caseinate and sodium caseinate reflected these differences, yielding non-monotonic and shear thinning flow behavior for calcium caseinate whereas sodium caseinate behaved only slightly shear thinning. It appears that the intrinsic properties of the dense caseinate dispersions, which are reflected in their rheological behavior, affect the structure formation that was found after applying shear. Therefore, rheological measurements are useful to obtain an indication of the structure formation potential of caseinate dispersions.
Advances in structure formation of anisotropic protein-rich foods through novel processing concepts
Manski, J.M. ; Goot, A.J. van der; Boom, R.M. - \ 2007
Trends in Food Science and Technology 18 (2007)11. - ISSN 0924-2244 - p. 546 - 557.
induced phase-separation - simple shear-flow - molecular-weight polyethylene - semidilute polymer-solution - nonfat mozzarella cheese - wet spinning technique - extrusion-cooking - wormlike micelles - colloidal dispersions - neutron-scattering
Development of protein-rich food products is currently limited by lack of scientific insights in structuring processes. The application of well-defined flow appears to be a good tool to create novel anisotropic food structures, on one hand, and to improve understanding of the behavior of protein-rich materials during processing, on the other hand. Concentrated protein dispersions show similarities with polymer systems under flow. Also in protein dispersions, the size of structural elements and interactions present account for structural changes due to flow. These insights can form a basis for the design of dedicated food structuring equipment
Polylactide films formed by immersion precipitation: Effects of additives, nonsolvent, and temperature
Sawalha, H.I.M. ; Schroën, C.G.P.H. ; Boom, R.M. - \ 2007
Journal of Applied Polymer Science 104 (2007)2. - ISSN 0021-8995 - p. 959 - 971.
induced phase-separation - pvdf membrane formation - asymmetric membranes - systems - water - morphology - methanol - transitions - mechanism - behavior
The influence of nonsolvent, crystallinity of the polymer film, and addition of dodecane (a poor solvent for the polymer and for the nonsolvent) on the morphology of polylactides films has been investigated and was related to phase separation behavior. Both amorphous poly-DL-lactide (PDLLA) and crystalline poly-L-lactide (PLLA) were dissolved in dichloromethane, and subsequently films were made by immersion in nonsolvent baths. PDLLA gave dense films without any internal structure, since the structure was not solidified by crystallization or glassification. PLLA films show varying structure depending on the nonsolvent. With methanol, asymmetric morphologies were observed as a result from combined liquid-liquid demixing and crystallization, while with water symmetric spherulitic structures were formed. As a next step, dodecane was added, which is not miscible with the nonsolvent, and we found it to have a strong influence on the morphology of the films. The PDLLA films with dodecane did not collapse: a closed cell structure was obtained. In PLLA films, dodecane speeds up phase separation and induces faster crystallization in the films, and the porosity, size of the pores, and interconnectivity increased. When the PLLA solutions were subjected to a heat pretreatment, crystallization could be postponed, which yielded a cellular structure around dodecane, which did not contain spherulites anymore