Food microstructure formation

In this chapter we have outlined how the use of a universal thermodynamic approach can provide valuable insight into the consequences of specific kinds of biopolymer-biopolymer interactions. The advantage of the approach is that it leads to clear quantitative analysis and predictions. It allows connections to be made between the molecular scale and the macroscopic scale, explaining the contributions of the biopolymer interactions to the mechanisms of microstructure formation, as well as to the appearance of novel functionality arising from the manipulation of food colloid formulations. Of course, we must remind ourselves that, taken by itself, the thermodynamic approach cannot specify the molecular or colloidal structures in any detail, nor can it give us information about the rates of the underlying kinetic processes. 

Heertje, I., et al. 1985. Structure formation in acid milk gels. Food Microstructure 4 267-278. 

Cho KY, Rizvi SSH. 2009a. 3D microstructure of supercritical fluid extmdates. 1 Melt rheology and microstructure formation. Food Res Internat 42 595-602. 

It has been found that a decrease in the initial porosity in the food may reduce oil absorption (Pinthus et al., 1995). However, as explained by the authors, crust formation plays an additional and fundamental role as soon as frying commences. As the moisture turns to steam and exits the product, it leaves behind a sponge-like tunnel network, which constitutes the oil reservoir. In accordance, the microstructure of the crust region,... 

This complex unit operation involves significant microstructural changes in fact, most of the desirable characteristics of fried foods are derived from the formation of a composite structure a dry, porous, crispy and oily outer layer or crust, and a moist cooked interior or core, whose microstructures form during the process (Bouchon et al., 2001). The high temperatures (around 160 and 180°C) cause water evaporation, which is transferred from the food towards the surrounding oil, whereas oil is absorbed by the food replacing part of the released water. This process results in products with a unique flavor-texture combination (Mellema, 2003). 

The structure (e.g., number, size, distribution) of fat crystals is difficult to analyze by common microscopy techniques (i.e., electron, polarized light), due to their dense and interconnected microstructure. Images of the internal structures of lipid-based foods can only be obtained by special manipulation of the sample. However, formation of thin sections (polarized light microscopy) or fractured planes (electron microscopy) still typically does not provide adequate resolution of the crystalline phase. Confocal laserscanning microscopy (CLSM), which is based on the detection of fluorescence produced by a dye system when a sample is illuminated with a krypton/argon mixed-gas laser, overcomes these problems. Bulk specimens can be used with CLSM to obtain high-resolution images of lipid crystalline structure in intricate detail. 

Lucey, J.A., Tamehana, M., Singh, H., and Munro, P.A. 1998. A comparison of the formation, rheological properties and microstructure of acid skim milk gels made with a bacterial culture or glucono-delta-lactone. Food Res. Imernatl. 31 147-155. 

Dubey NB, Windhab El (2013) Iron encapsulated microstructured emulsion-particle formation by prhhng process and its release kinetics. Journal of Food Engineering 115 198-206. 

The important properties unique to microemulsions - thermodynamic stability, ultra-low interfacial tensions, translucence, small and tunable microstructures - make microemulsions interesting for a variety of applications. Microemulsions find application as a reaction medium for formation of polymeric and inorganic nanoparticles, for the dispersion of drugs, food stuffs, agrochemicals, and cosmetic ingredients, and in detergency, the enhancement of oil recovery from reservoirs, and the extraction of contaminated solids (17). 

Amend, X, Belitz, H.-D. Microstructural studies of gluten and a hypothesis on dough formation. Food Structure 10, 277 (1991)... 

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