Foods foams, structure measurement

Assuming that structural data are available, and that a property has been correctly measured, the next problem is to establish a relationship. Fundamental models are preferred by engineers because tlrey are based on basic principles of physics and the physical chemistry of the described phenomenon. Once it is realized that foods are essentially composite hierarchical structures, we can borrow models and theories developed for nonfood systems and apply them. A good example is the adaptation of mechanical principles for the description of cellular solids, (Gibson and Ashby 1988) to the properties of solid food foams (Attenburrow et al. 1989 Warburton et al. 1990). Examples are provided in Chapter 10. 

Connectivity may be defined as the maximal number of particles (branches, cell walls, and so on) that may be cut without separating the structure. For several porous foods, such as foamed chocolate bar, honeycomb chocolate bar, chocolate muffin, marshmallow, and strawberry mousse, air cell connectivity was defined as a measure of the relative convexity or concavity of the total slid surface (Lim and Barigou, 2004). Concavity indicates connectivity, whereas convexity indicates isolated disconnected structures. Through the image analysis, authors compare the solid area and perimeter before and after an image dilation operation and calculate the index of connectivity as the following ... 

A correlation between content of hydrophobic amino acids and surface activity of five different food proteins partially hydrolyzed with 0.1% pepsin has been reported (58), but exceptions were noted. Protein hydrolysates exhibiting large surface absorption were correlated with large foam stability and a large external hydrophobic region. It was concluded that protein hydrolysates with large surface hydrophobic regions adsorbed more readily at interfaces and rates of surface desorption were lower. However, secondary structures, as measured by optical rotatory dispersion and infrared spectra, and the content of the total hydrophobic amino acids in the protein hydrolysates showed no correlation with their foam stabilities (58). 

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