Rheology of concentrated crystal suspensions: sucrose fondants as hard particles in soft matter
Hard particle dispersions are abundant in food as well as technical applications. In particular, the production of many candies like fondants, crystalline sugars or creamed honeys involves agitation of concentrated suspensions of microscopic crystals in saturated solutions. However, the complex rheo...
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Frontiers Media S.A.
2025-02-01
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| Series: | Frontiers in Soft Matter |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/frsfm.2025.1527707/full |
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| author | Hannah M. Hartge Hannah M. Hartge Eckhard Flöter Thomas A. Vilgis |
| author_facet | Hannah M. Hartge Hannah M. Hartge Eckhard Flöter Thomas A. Vilgis |
| author_sort | Hannah M. Hartge |
| collection | DOAJ |
| description | Hard particle dispersions are abundant in food as well as technical applications. In particular, the production of many candies like fondants, crystalline sugars or creamed honeys involves agitation of concentrated suspensions of microscopic crystals in saturated solutions. However, the complex rheological behavior of such non-colloidal suspensions with poly-disperse, irregular particles is not fully understood. This work investigates different sucrose suspensions with a particle volume fraction of about 50%. After detailed image analysis of the varying particle size distributions and shapes, the flow properties are investigated by oscillatory rheology. Amplitude sweeps, frequency sweeps and thixotropy tests show the dependency of rheological behavior on the microstructure of the suspensions. In particular, all samples show characteristic strain softening with subsequent strain hardening that indicates jamming at large strains. This is observed irrespective of specifics in the particle shape and material, suggesting universal behavior due to the high particle volume fraction. They also show significant time-dependent behavior. However, sedimentation rates are higher and structure rebuilding is lower for larger particle sizes and dispersity. The observed strain softening and structure rebuilding are explained by rearrangement of the crystals: Under moderate strain amplitudes, friction and collisions are minimized, with a larger optimization potential for larger dispersities. When oscillations are reduced again, mainly small particles re-arrange in an arbitrary order over time, leading to an increase in loss and storage modulus and thus thixotropic behavior. This time-dependent process needs to be taken into account when measuring or processing concentrated crystal suspensions. Our findings contribute to a better understanding of concentrated suspensions simple in composition, but complex in their flow properties. The observed behavior strongly depends on the particle-particle interactions. Thus, our findings can be transferred to other areas involving concentrated, non-Brownian frictional suspensions of compact hard particles, as they are often found in food, technical applications or geology. |
| format | Article |
| id | doaj-art-165eccff55a841b6a6c3f7ad91a0e7c9 |
| institution | Kabale University |
| issn | 2813-0499 |
| language | English |
| publishDate | 2025-02-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Soft Matter |
| spelling | doaj-art-165eccff55a841b6a6c3f7ad91a0e7c92025-02-04T15:59:19ZengFrontiers Media S.A.Frontiers in Soft Matter2813-04992025-02-01510.3389/frsfm.2025.15277071527707Rheology of concentrated crystal suspensions: sucrose fondants as hard particles in soft matterHannah M. Hartge0Hannah M. Hartge1Eckhard Flöter2Thomas A. Vilgis3Soft Matter Food Physics Group, Max Planck Institute for Polymer Research, Mainz, GermanyDepartment of Food Process Engineering, Technische Universität Berlin, Berlin, GermanyDepartment of Food Process Engineering, Technische Universität Berlin, Berlin, GermanySoft Matter Food Physics Group, Max Planck Institute for Polymer Research, Mainz, GermanyHard particle dispersions are abundant in food as well as technical applications. In particular, the production of many candies like fondants, crystalline sugars or creamed honeys involves agitation of concentrated suspensions of microscopic crystals in saturated solutions. However, the complex rheological behavior of such non-colloidal suspensions with poly-disperse, irregular particles is not fully understood. This work investigates different sucrose suspensions with a particle volume fraction of about 50%. After detailed image analysis of the varying particle size distributions and shapes, the flow properties are investigated by oscillatory rheology. Amplitude sweeps, frequency sweeps and thixotropy tests show the dependency of rheological behavior on the microstructure of the suspensions. In particular, all samples show characteristic strain softening with subsequent strain hardening that indicates jamming at large strains. This is observed irrespective of specifics in the particle shape and material, suggesting universal behavior due to the high particle volume fraction. They also show significant time-dependent behavior. However, sedimentation rates are higher and structure rebuilding is lower for larger particle sizes and dispersity. The observed strain softening and structure rebuilding are explained by rearrangement of the crystals: Under moderate strain amplitudes, friction and collisions are minimized, with a larger optimization potential for larger dispersities. When oscillations are reduced again, mainly small particles re-arrange in an arbitrary order over time, leading to an increase in loss and storage modulus and thus thixotropic behavior. This time-dependent process needs to be taken into account when measuring or processing concentrated crystal suspensions. Our findings contribute to a better understanding of concentrated suspensions simple in composition, but complex in their flow properties. The observed behavior strongly depends on the particle-particle interactions. Thus, our findings can be transferred to other areas involving concentrated, non-Brownian frictional suspensions of compact hard particles, as they are often found in food, technical applications or geology.https://www.frontiersin.org/articles/10.3389/frsfm.2025.1527707/fullrheologyfondantstrain softeningstrain hardeningthixotropycrystal suspension |
| spellingShingle | Hannah M. Hartge Hannah M. Hartge Eckhard Flöter Thomas A. Vilgis Rheology of concentrated crystal suspensions: sucrose fondants as hard particles in soft matter Frontiers in Soft Matter rheology fondant strain softening strain hardening thixotropy crystal suspension |
| title | Rheology of concentrated crystal suspensions: sucrose fondants as hard particles in soft matter |
| title_full | Rheology of concentrated crystal suspensions: sucrose fondants as hard particles in soft matter |
| title_fullStr | Rheology of concentrated crystal suspensions: sucrose fondants as hard particles in soft matter |
| title_full_unstemmed | Rheology of concentrated crystal suspensions: sucrose fondants as hard particles in soft matter |
| title_short | Rheology of concentrated crystal suspensions: sucrose fondants as hard particles in soft matter |
| title_sort | rheology of concentrated crystal suspensions sucrose fondants as hard particles in soft matter |
| topic | rheology fondant strain softening strain hardening thixotropy crystal suspension |
| url | https://www.frontiersin.org/articles/10.3389/frsfm.2025.1527707/full |
| work_keys_str_mv | AT hannahmhartge rheologyofconcentratedcrystalsuspensionssucrosefondantsashardparticlesinsoftmatter AT hannahmhartge rheologyofconcentratedcrystalsuspensionssucrosefondantsashardparticlesinsoftmatter AT eckhardfloter rheologyofconcentratedcrystalsuspensionssucrosefondantsashardparticlesinsoftmatter AT thomasavilgis rheologyofconcentratedcrystalsuspensionssucrosefondantsashardparticlesinsoftmatter |