Introduction and objectives. Malnutrition can affect 50% of the frailest elderly population and is one of the critical factors affecting the quality of life of elder people and with a direct impact in their health. An average of 45% seniors has symptoms of dysphagia affecting their eating habits by reducing food intake and appetite. Some biopolymers when nanoestructured as nanoparticles, nanofibres or nanotubes have new textural, surface and optical properties making them particularly suitable for dysphagia and palatability problems.
This is the case α-Lactalbumin (α-La) contained in cow milk that has also self-assembly properties when is partially hydrolyzed by a serine endoprotease resulting in the formation of nanotubes in the presence of a divalent cation (Graveland- Bikker et al., 2004). The objective of this work is to obtain by means of the kinetic control of the self-assembly process tailor made nanotubes of α-La in order to modify the structure and rheological properties of α-La solutions to use them for dysphagia patients. Development and Results. In order to study the α-La nanotube formation process the effects of the following variables were studied: concentration of divalent cation, temperature and reaction time. Nanotube elongation, branching and shape could be easily tailor made using different reaction conditions. For example, α-La aggregation in presence of Ca2+ is slower than in presence of Mn2+ and the gels obtained with Ca2+ are weak and sometimes turbid. In contrast the gels obtained with Mn2+ are stronger and more transparent. The lag time previous to nanotube elongation was related with both hydrolysis and self-assembly. When the temperature increase the formation of nanotubes is faster and the lag time becomes shorter. Gels obtained at higher temperatures and higher Mn2+ concentration are strongest and most transparent, which would be optimal to enhance the structure and functionality of foods. Conclusión. Different new physical properties of α-La solutions and macroestructures can be obtained from the formation of nanostructures. By means of the kinetic control of α-La nanotube formation transparent solid gels or increase of viscosity in the α-La solutions can be easily obtained. These gels are suitable to design food for dysphagia patients.
Referencias: Graveland-Bikker JF, Ipsen R, Otte J, de Kruif CG, Langmuir, 2004, 20, 6841-6846.