Physicochemical Properties and Heat Stability of Whey Protein Isolate-Lactose Conjugates Formed by Dry-Heating

Norliza Julmohammad; Don Otter; Yacine Hemar; Umi Hartina Mohd Razali; Sarizan Sabari.

Transactions on Science and Technology, 8(3-2), 191 - 198.

Back to main issue

Conjugation via MR consider as the safest and potential method in food industry. However, it is important to control the extent of conjugation via MR since the browning effect could lead to the health issues. There is great interest to understand the chemistry of MR, to improve the physicochemical properties, and to discover the potential of Maillard products with various functionalities. Whey protein isolate (WPI) has become an important source of functional ingredients in various health-promoting foods. However, WPI have problem with thermal instability that present during food processing. Therefore, this study aims to investigate the effect of dry-heating at different incubation time, then monitor the physicochemical properties and heat stability of WPI-Lactose conjugates. Conjugation of WPI with lactose was achieved by dry‐heating with the ratio of lactose to WPI 1:0.4 (wt/wt). Incubation time varying from 0 to 10 days at 40°C and water activity Aw = 0.79. o-pthaldialdehyde (OPA) assay was used to monitor the extent of conjugation. An incubation time of 3 days was selected as the standard conjugation time based on conjugation rates and the degree of Maillard browning. The result revealed that WPI-Lactose conjugates at 3 days incubation has slightly improved heat stability of protein. Thus, a new approach of WPI-Lactose conjugates has potential to produce better heat resistance milk protein products in the future.

KEYWORDS: WPI-Lactose conjugates; Maillard Reaction (MR); Dry-Heating; Physicochemical Properties; Heat Stability

Download this PDF file

  1. Anema, S. G., Lauber, S., Lee, S. K., Henle, T. & Klostermeyer, H. 2005. Rheological properties of acid gels prepared from pressure - and transglutaminase-treated skim milk. Food Hydrocolloids, 19(5), 879–887.
  2. Burrington, K.J. 2012. Whey protein heat stability. U.S. Dairy Export Council. ( Last accessed on 28 October 2021.
  3. Chen, Y., Chen, X., Guo, T. L. & Zhou, P. 2015. Improving the thermostability of β-lactoglobulin via glycation: The effect of sugar structures. Food Research International, 69, 106-113.
  4. Doost, A.S., Nasrabadi, M.N., Wu, J., A'yun, Q. & Van der Meeren, P. 2019. Maillard conjugation as an approach to improve whey proteins functionality: A review of conventional and novel preparation techniques. Trends in food science & technology, 91, 1-11.
  5. Durowoju, I. B., Bhandal, K. S., Hu, J., Carpick, B. & Kirkitadze, M. 2017. Differential Scanning Calorimetry - A Method for Assessing the Thermal Stability and Conformation of Protein Antigen. Journal of visualized experiments : JoVE, 121, 55262.
  6. Julmohammad, N. 2017. Synthesis of Lactose Phosphate and its Conjugation with Whey Proteins. PhD Thesis, University of Auckland.
  7. Lund, M.N. & Ray, C.A. 2017. Control of Maillard reactions in foods: Strategies and chemical mechanisms. Journal of Agricultural and Food Chemistry, 65(23), 4537-4552.
  8. Maillard, L. C. 1912. Action of amino acids on sugars. Formation of melanoidins in a methodical way. Comptes Rendus, 154, 66–68.
  9. Nacka, F., Chobert, J. M., Burova, T., Léonil, J. & Haertlé, T. 1998. Induction of new physicochemical and functional properties by the glycosylation of whey proteins. Journal of Protein Chemistry, 17(5), 495–503.
  10. Oliver, C. M., Melton, L. D. & Stanley, R. A. 2006. Creating Proteins with Novel Functionality via the Maillard Reaction: A Review. Critical Review in Food Science and Nutrition, 46(4), 337-350.
  11. Sun, J., You, X., Li, L., Peng, H., Su, W., Li, C. & Liao, F. 2011.Effects of a phospholipase D inhibitor on postharvest enzymatic browning and oxidative stress of litchi fruit. Postharvest Biology and Technology, 62(3), 288-294.
  12. Visser, R. A. 1988. Crystal growth retarding of alpha-lactose hydrate by sugar phosphates, a continued study. Netherlands Milk and Dairy Journal, 42, 449-468.