Accurate determination of key surface properties that determine the efficient separation of bovine milk BSA and LF proteins

The aim of this work is to accurately measure fundamental surface properties, i.e., zeta potential, isoelectric point and protein size that determine the optimal separation conditions of Bovine serum albumin and lactoferrin, two high added value food proteins whose similarity in weight makes their separation a scientific and technical challenge. The systematic study of these proteins’ surface properties was performed under different conditions: (i) 3.0 < pH < 10.0, (ii) electrolyte type: KCl, NaCl and CaCl2 and concentration (0.01–0.1 M KCl) and (iii) protein concentration in the range of 0.04–4.0 g L-1 for BSA and 0.01–1.0 g L-1 for LF with the objective of establishing the optimal separation conditions. Finally, the comparison of the experimental and theoretically calculated values revealed significant deviations under specific conditions, highlighting the simplicity of the theoretical assumptions and leading to the conclusion that the use of experimental surface properties is still needed for the correct design of food protein separation processes.Financial support from the Projects CTQ2011-25262, CTM2011- 23912 and CTQ2012- 31639 (Ministerio de Economía y Competitividad-MINECO/SPAIN and Fondo Europeo de Desarrollo Regional-FEDER) is gratefully acknowledged

Spontaneous Assembly and Induced Aggregation of Food Proteins

Beyond their nutritional value, food proteins are a versatile group of biopolymers with a considerable number of functionalities throughout their extensive structures, conformations and interaction–aggregation behaviour in solution. In the present paper, we give an overview of the induced aggregation and spontaneous reversible assembly of food proteins that lead to a diversity of supramolecular structures. After a brief description of the properties of some food proteins, the first part summarises the aggregation processes that lead to supramolecular structures with a variety of morphologies and sizes. The second part reports on the requirements that drive spontaneous assembly of oppositely charged proteins into reversible supramolecular structures. The promising new applications of these structures in food and non-food sectors are also mentioned