Food Nanotechnology: Current Developments and Future Prospects
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minimize the formation of mineral deposits and to allow easier cleaning, which would aid the processing of liquid foods significantly. The in-depth study of membrane fouling in membrane separation processes, such as microfiltration and ultrafiltration, has also been approached using AFM (James et al., 2003).
IV. DEVELOPMENT OF NOVEL NANO-STRUCTURES FOR FOOD APPLICATIONS Nanotechnology has provided unprecedented opportunities for the development of novel nanomaterials and the investigation of their properties at the nanoscale. Nanomaterials can be found in nature, such as nanoparticles existing in soil (clays, zeolites, imogolite, iron, and manganese oxides), but they can also be created through nanotechnology itself (Takhistov, 2006). Nanostructured materials exhibit unique properties that open windows of opportunity for the creation of new, high-performance materials that will have a critical impact on food manufacturing, packaging, and storage. Some examples of how nanomaterials can be used in food applications will be discussed in the following section.
IV.A. Manipulation of molecules at nanoscale for improved processing Freezing is one of the best methods known for food preservation. When properly processed, packaged, and stored, frozen foods come close to fresh foods in terms of nutrition, color, flavor, and texture; however, temperature fluctuations in the frozen product may cause the free water to experience several cycles of ice formation and melting. This can lead to a number of undesirable effects, including moisture migration, dehydration, structural breakdown, and formation of large ice crystals, imparting a gritty mouthfeel upon consumption of the product. By using purified extracellular ice nucleators (ECIN), ice nucleation temperatures can be elevated, which promotes freezing and reduced freezing time and leads to significant energy savings (Li and Lee, 1995; Zasypkin and Lee, 1999). Recently, Huang (current author) and associates at Rutgers University developed a new processing method that forms a nanoscale ECIN coating on the surface of polymer films by using the layer-by-layer (LbL) approach. LbL is widely used in the construction of multilayer films of polyelectrolytes for formation of two-dimensional structures on flat substrates. With suitable control of the charge density of the polyelectrolyte solution, it is possible to dramatically manipulate the molecular organization, surface morphology, and mechanical properties of the multilayer films (Decher, 1997). Lin et al. (2008) used the quartz crystal microbalance with dissipation monitoring (QCM-D)