Silicone rubbers food applications

Schmid et al. used the same principle to develop sensors to be incorporated into FI systems for the determination of ascorbic acid in fruit juices [38] and that of lactic acid in dairy products [39]. The membrane used in both applications consisted of decacyclene dissolved in silicone rubber that was treated similarly as the membrane in glucose sensors (Fig. 3.4.B). The oxygen optrode was coated with a sheet of carbon black as optical insulation in order to protect it from ambient light or intrinsic sample fluorescence. Ascorbic acid oxidase or lactic acid oxidase was immobilized by adsorbing it onto carbon black and cross-linking it with glutaraldehyde. The FI system automatically buffered and diluted the food samples, thereby protecting the biosensor from a low pH and interferents. 

There is a separate Council of Europe Resolution, APRes (2004), on silicone materials for food contact. The resolution defines the silicone product group being comprised of silicone rubbers, silicone liquids, silicone pastes and silicone resins. Blends of silicone rubber with organic polymers are covered by the resolution where the silicone monomer units are the predominant species by weight. Silicones that are used as food additives or processing aids (e.g. as defoamers in the manufacture of substances such as wine) are not covered by this resolution, but polysiloxanes used as emulsifiers are. The resolution gives an overall migration limit of 10 mg/dm of the surface area of the product or material, or 60 mg/kg of food. There are restrictions on the types of monomers that can be used to produce the silicone polymers and there is an inventory list Technical document No. 1 - List of substances used in the manufacture of silicone used for food contact applications . 

Silicone rubber tubes are mainly utilized in medical and food technology e.g. as transfusion tubes, catheters and tubes for drinks. Silicone cables are widely utilized in applications for which thermal stability, weathering resistance and chemical resistance are required e.g. baking ovens, hot lamps and electrical connections for electrical motors and transformers. 

Uses of Silicone Rubbers. Becanse of their high cosL silicone elastomers are used only in applications where other elastomers fail. They are mainly nsed in applications requiring high heat resistance and extreme low-temperature flexibility. These elastomers are used in the electricaL electronic, aerospace, antomotive, mechanical equipment, fighting, cable, and textile indnstries. They are also nsed in pharmacentical and medical applications for components in contact with food. They are now nsed in high-temperature cooking utensils (e.g., scrapers and spatulas). 

Regarding food packaging applications or food contact materials, there are few approaches made in this direction, considering especially silicones. This class of materials possesses properties such as (1) water and oil repelling (2) gas permeability and (3) insolubility in water, mineral oils, or alcohol [99]. Silicone rubber was also reported to be used for membrane vessels in the transport of human islets because it reduces the risk of hypoxia and thus reduces the risk of dysfunction or death [103]. 

Silicone rubbers, both, peroxide and addition curing, are used in the manufacture of composite parts. Known applications focus on automotive, medical, sanitary, household, transmission and distribution (T D), electronics and food appliances. 

Compoimd crosslinking silicone rubbers do not form fission products during crosslinking. However, despite the high degree of complete chemical reaction, a 100% reaction cannot be achieved. This means that volatile polymer components remain behind in the finished part. For applications in the food industry or in medical areas, liquid as well as solid silicone rubber products must be tempered in accordance with regulations, for example the German BgW and in the US the FDA. 

A very high proportion of the usage of silicone rubbers is associated with electrical applications, particularly wire and cable for the electrodomestic appliance and automotive industries. The inherent properties of silicone rubber make it a natural choice in areas such as safety (flame retardant) cables and food contact applications. Examples of the latter uses are given. In addition reference is made to automotive hose, electrically conductive applications, dynamic seals and medical implants. 

National agencies concerned with regulating the materials for contact with food and drugs plus para-medical uses have long recognised the basic suitability of silicone rubber for such applications. The permitted silicone polymer types, fillers and additives are listed, for example in F.D.A. 21 CFR 177.2600 (USA) and Bundesgesundheitsblatt XV.Ill (Germany). 

The major products containing Si are siliconesf which are polymeric compounds having Si—O bonds. Silicones are used in various industrial fields such as the electric and electronic industries, business machinery and tools, constructions, foods, medical treatments, fibers, plastics, papers, pulps, paints, rubbers, etc. The kind of goods manufactured are three thousand or more, and increasing all the time [2]. Therefore, the number of patent applications for silicones and silanes are many and there are 4000-5000 per year in Japan. The field of organosilicon compounds is the most active of the organometallic compounds [2]. 

There are three main forms of silicones, namely liquids, solids (resins) and rubbers. The resins are the most important from the food contact point of view. A major application is in the bakery industry where the resin is used to coat bread baking tins. 

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