Water-binding of protein particles

Abstract

As overweight and obesity become more prevalent in society, the demand for food products that can help maintain body weight increases. One way to make such products is by decreasing the protein and fat content through increasing the water content. This thesis describes the potential of protein microparticles (MPs) to bind ≥ 90% w/w water tightly without negatively influencing sensory perception. Therefore, two types of MPs were prepared: heat- and cold-gelated MPs. In addition, pea protein isolate, soy protein isolate, lupin protein concentrate and vital wheat gluten particles were used. To determine their water-binding capacity (WBC), pellets were made by centrifuging dispersions of those particles. These measurements showed that some of these pellets can bind ≥ 90% w/w water. However, the WBC of a pellet contains both water bound within and between the particles, which means that the WBC of a pellet is always unequal to the WBC of the protein particles themselves. To gain more insight in these two water domains and the pellet as a whole, a combination of time domain nuclear magnetic resonance and microscopy was found to be useful. From the measurements, it was concluded that the WBC of a pellet is determined by the structure of protein particles (nanostructure) as well as the structure between particles (microstructure). Overall, the WBC of pellets being larger than that of particles themselves suggests that pellets are a good alternative to the use of MPs for the purpose of increasing the water content of a product, provided they remain a network in the product.