Using DLS-Microrheology and Raman Spectroscopy to probe self-assembly and gelation mechanisms in food based complex fluids
S.Amin1, S.Blake1, E.N.Lewis1, L.Kidder1, S.Kenyon1, J.Duffy2, S.Carrington2
1Malvern Instruments, 7221 Lee Deforest Drive, Suite 300 Columbia Maryland, USA
2Malvern Instruments Ltd, Enigma Business Park, Grovewood Road, Malvern, WR141XZ, UK
Contact Email:samiul.amin@malvern.com
Summary: Complex fluids such as biopolymers and protein dispersions play a critical role in providing both functional and sensory benefits in many processed foods. The process of self-assembly in these complex materials and their associated rheological response need to engineered to provide stability, texture and any additional functional benefits. Controlling such behaviour requires manipulation of the micro/mesostructure often by controlling the extent of intermolecular/intramolecular associations and interactions between components.
Most insights into the self-assembly process and the corresponding changes in rheological behaviour have primarily focused on elucidating micro/mesostructural changes through various scattering (light, x-ray, neutron) and imaging techniques (cryo-TEM, SEM, AFM). Furthermore detailed insights into the associated chemical conformational/molecular structural changes and various non-covalent interactions (e.g. H-bonds, hydrophobic interactions) leading to the self-assembly process have been very limited. An understanding of the molecular level structural changes as self-assembly and gelation progresses can provide new mechanistic insights that can assist the formulation development process. 
The talk will show how the combination of mesoscale structure-property elucidation techniques such as DLS/optical microrheology combined with high resolution chemical structure/conformation elucidation techniques such as Raman Spectroscopy can generate novel mechanistic insights for complex fluids and soft matter systems that are commonly encountered in food applications. This will be exemplified through studies into the self-assembly/gelation mechanism in a thermo-reversible gel forming agarose and a widely utilized food protein--lactoglobulin undergoing temperature induced aggregation and self-assembly.
References:
1.	S.Amin, S.Blake, S.M.Kenyon, R.C.Kennel, E.N.Lewis, A Novel Combination of DLS-optical microrheology and low frequency Raman spectroscopy to reveal underlying biopolymer self-assembly and gelation mechanisms. Journal of Chemical Physics, 141, 234201 (2014).
2.	S. Amin, C. A. Rega and H. Jankevics, Detection of viscoelasticity in aggregating dilute protein solutions through dynamic light scattering-based optical microrheology. Rheol. Acta 51 (4), 329-342 (2012).