Liquid-Core Beads and Their Applications in Food, Biotechnology, and Other Fields
In 1971, Maddox’s patent on soft gelatin capsules was approved. In 1980, Lim and Sun published their hallmark study in which microencapsulated islets were used as a bioartificial pancreas. In that manuscript, alginate-polylysine liquid-core capsules were
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Liquid-Core Beads and Their Applications in Food, Biotechnology, and Other Fields
7.1 Introduction Fluid-filled cores are found in many research fields, such as biotechnology, food, and medicine. However, literature and cinematography are also more than a little familiar with them. As children, we were all fascinated by Jules Verne’s fantastic voyage to the center of the Earth. A more recent movie, “The Core,” directed by Jon Amiel, deals with the issue of our planet’s liquid core which has stopped spinning and the heroic crew that is trying to restore Earth’s magnetic field by nuclear means. Astronomy is replete with examples of fluid-filled cores. Three years of radio-tracking data from the Mars Global Surveyor spacecraft concluded that Mars, the Red Planet, has a molten liquid-iron core. The core is about one-half the size of the planet, as is the case for Earth and Venus, and contains a significant fraction of a lighter element, similar to sulfur. Mars has not cooled to a completely solid iron core; rather, its interior is made up of either a completely liquid iron core or a liquid outer core with a solid inner core (NASA 2003). NASA’s results were published in the March 7, 2003, online issue of the journal Science. In another example, analysis of seismic waves generated by the June 1996 earthquake in Indonesia provided proof that inside a liquid core, the very center of the Earth is solid. In 1995, a sea-based Russian rocket was used to carry out the first German microgravity experiment. The experiment, which was funded by the German space agency, simulated thermal convection with respect to the geophysical motion in the Earth’s inner liquid core (NASA 2003). Thus, liquid cores are clearly not limited to microscopic phenomena. Another interesting example from the macroscopic world is a string-wrapped, liquid-core golf ball, constructed by mechano-chemical reaction using PVA for the polymer backbone. The ball is composed of a bag containing a dispersion of highdensity particles in water. The bag is wrapped with rubber strings for further tactile improvement. Another option is to replace the liquid core with a highly elastic gel. Although this is an interesting idea, such balls are not frequently used due to the significant improvements in the construction and performance of two-piece solid balls and a consequent lack of commercial interest (Tomita 2001). These are but a few examples of the ubiquitous distribution of fluid-core objects and their importance. A. Nussinovitch, Polymer Macro- and Micro-Gel Beads: Fundamentals and Applications, DOI 10.1007/978-1-4419-6618-6_7, C Springer Science+Business Media, LLC 2010
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Liquid-Core Beads and Their Applications
7.2 General Encapsulation, on a micro- or macroscale, is a specialized form of edible packaging. In food processes, the approach is to encapsulate only those ingredients which are unstable, volatile, or particularly reactive. Thus, creating an envelope around those ingredients provides the whole product with stability and protection (Daniels 197
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