Microstructure and rheology of whey protein based hydrogels

Abstract

Protein hydrogels have great potential for food and biomedical applications due to their ability to create three dimensional gel networks. A dairy industry by-product whey contains valuable proteins capable of forming gels with the ability of holding excess amount of water and entrap active ingredients. This enables a wide use of whey proteins for various applications in food formulations. Whey protein gelation is commonly promoted by heat and the gel characteristics can be enhanced by blending whey proteins with suitable carbohydrates. Mechanical properties and microstructure of gel networks determine their availability for target applications such as entrapment of active agents by maintaining their stability, target delivery and texture improvement of food products. The objective of this study was to investigate structural and mechanical features of whey protein -sodium alginate gels using microscopy, spectroscopy and rheometry. Rheological and structural properties of gels obtained by different preparation protocols and composition differed significantly. Porosity in the gel microstructure changed remarkably as the gel composition changed. Also, some conformational changes were tracked by studying the secondary structure of proteins during gel formation. Further research will focus on investigation of these whey protein-based gels for the entrapment ability and release behavior of bioactive components.

Keywords

• whey proteins
• gelation
• sodium alginate
• microstructure
• spectroscopy

References

1. 1. Flory, P. J., Principles of polymer chemistry. Ithaca, NY: Cornell University Press, USA, 1953.
2. 2. Gunasekaran, S., Ko, S., Xiao, L., Use of whey proteins for encapsulation and controlled delivery applications, Journal of Food Engineering, 83 (2007) 31–40.
3. 3. Buitrago, J.O., Patel, K.D., El-Fiji, A., Lee, J-W., Kundu, B., Lee, H-H., Kim, H-W., Silk fibrion/collagen protein hybrid cell-encapsulating hydrogels with tunable gelation and improved physical and biological properties, Acta biomaterialia, 69 (2018) 218-233.
4. 4. Nojima, T., Iyoda, T., Egg white-based strong hydrogel via ordered protein condensation, NPG Asia Materials, 10 (2018) 460-465.
5. 5. Reddy, N., Yang, Y., Potential of plant proteins for medical applications, Trends in Biotechnology, 29 (2011) 490-498.
6. 6. Abaeea, A., Mohammadian, M., Jafaria, S.M., Whey and soy protein-based hydrogels and nano-hydrogels as bioactive delivery, Trends in Food Science & Technology, 70 (2017) 69-81.
7. 7. Wan, Z-L., Guo, J., Yang, X-Q., Plant protein-based delivery systems for bioactive ingredients in foods, Food & Function, 6 (2015) 2876-2889.
8. 8. Calo, E., Khutoryanskiy, V.V., Biomedical applications of hydrogels: A review of patents and commercial products, European Polymer Journal, 65 (2015) 252–267.

9. 9. Jonker, A.M., Löwik, D.W.P.M. and van Hest, J.C.M., Peptide- and Protein-Based Hydrogels, Chem. Mater. 24 (2012) 759−773.
10. 10. Damodaran, S., 2017. Food Proteins and Their Applications, Routledge, 2017.
11. 11. Tarhan O., Spotti M.J., Schaffter S., Corvalan C.M., Campanella O.H., Rheological and Structural Characterization of Whey Protein Gelation Induced by Enzymatic Hydrolysis, Food Hydrocolloids 61 (2016) 211-220.
12. 12. Spotti M.J., Tarhan O., Schaffter S., Corvalan C.M., Campanella O.H., Whey Protein Gelation Induced by Enzymatic Hydrolysis and Heat Treatment: Comparison of Creep and Recovery Behavior, Food Hydrocolloids 63 (2017) 696-704.
13. 13. Li, J., Ould Eleya, M., & Gunasekaran, S., Gelation of whey protein and xanthan mixture: effect of heating rate on rheological properties. Food Hydrocolloids, 20 (2006) 678-686.
14. 14. Spotti, M.J., Perduca, M.J., Piagentini, A., Santiago, L.G., Rubiolo, A.C., Carrara, C.R., Does dextran molecular weight affect the mechanical properties of whey protein/dextran conjugate gels?, Food Hydrocolloids, 32 (2013) 204-210.
15. 15. Deat-Laine, E., Hoffart, V., Garrait, G., Beyssac, E., Whey protein and alginate hydrogel microparticles for insülin intestinal absorption: Evaluation of permeability enhancement properties on Caco-2 cells, Int. Journ.of Pharmaceuticals, 453 (2013) 336-342.
16. 16. Tarhan O., Tarhan E., Harsa S., Investigation of the Structure of alpha-Lactalbumin Protein Nanotubes using optical spectroscopy, Journal of Dairy Research, 81(2014) 98-106.
17. 17. Fitzsimons, S.M., Mulvihill, D.M., Morris, E.R., Denaturation and aggregation processes in thermal gelation of whey proteins resolved by differential scanning calorimetry, Food hydrocolloids, 21 (2007) 638-644.
18. 18. Ipsen, R.H., Otte, J., Qvist, K.B., Molecular self-assembly of partially hydrolysed α-lactalbumin resulting in strong gels with a novel microstructure, J.of Dairy Res., 68 (2001) 277-286.
19. 19. Verheul, M., Pedersen, J. S., Roefs, S. P. F. M., & de Kruif, K. G., Association behavior of native b-lactoglobulin. Biopolymers, 49 (1999) 11-20.
20. 20. Kelly, S. M., Jess, T. J., & Price, N. C., How to study proteins by circular dichroism. Biochimica et Biophysica Acta, 175 (2005) 119-139.
21. 21. Greenfield, N. J. (2006). Using circular dichroism spectra to estimate protein secondary structure. Nature Protocols, 1(2006) 2527-2535.