Journal of Food Processing & Technology

Evolutions of structural properties of native phospho casein (npc) powder during storage

Global Food Security and Sustainability Conference

September 05-07, 2016 Beijing, China

Sarah Nasser, Anne Moreau, Alain Hédoux, Romain Jeantet and Guillaume Delaplace

Centre National Interprofessionnel de lâ??Economie Laitière, France
INRA Processus aux Interfaces et Hygiène des Matériaux, France
UMET, France
INRA Laboratoire de Recherches de Technologie Laitière, France

Posters & Accepted Abstracts: J Food Process Technol

Abstract:

Background: Spray dried powders containing some casein are commonly produced in dairy industry. It is widely admitted that the structure of casein evolves during powder storage, inducing a loss of solubility. However, few studies evaluate accurately the destabilization mechanisms at molecular and mesoscopic level, in particular for Native Phospho Casein powder (NPC). Consequently, at the state of the art, it is very difficult to assess which secondary structure change or crosslinks initiate insolubility during storage. To address this issue, controlled ageing conditions have been applied to a NPC powder [which was obtained by spray drying a concentrate containing a higher content of casein (90%), whey protein (8%) and lactose (few %)]. Evolution of structure and loss of solubility, with the effects of temperature and time of storage were systematically reported. Methods: FTIR spectroscopy, Raman and Circular Dichroism were used to monitor changes of secondary structure in dry powder and in solution after rehydration. Besides, proteomic tools and electrophoresis have been performed after varying storage conditions for evaluating aggregation and post translational modifications, like lactosylation or phosphorylation. Finally, TOF-SIMS and MEB were used to follow in parallel evolution of structure in surface and skin formation due to storage. Results & Conclusion: These results highlight the important role of storage temperature in the stability of NPC. It is shown that the rise of post translational modifications, disulphide bridges and physical cross link contribute to the destabilisation of structure and aggregation of casein. A relative quantification of each kind of cross link, source of aggregates, is proposed. In addition, it has been proved that migration of lipids and formation of skin in surface during the ageing also explains the evolution of structure casein and thus the alterations of functional properties of NPC powder.

Biography :

Email: Nasser@lille.inra.fr