Sterilising tube

Browne s steriliser tubes contain a liquid that undergoes a slow chemical reaction at elevated temperatures, changing from red to amber then green. Only when they are green has the correct temperature time combination elapsed. Several of these indicator tubes should be distributed in each batch of material to be sterilised. It is important when autoclaving liquids, to place a Browne s tube in a bottle of liquid as the conditions within such a bottle differ from those outside. Different types of Browne s tubes are available for sterilisation using steam or dry heat. Type I (black spot) tubes are... 

Storage of a large pile of laminate pouches with packed, sterilised tubings and filling needles... 

The rubbers are also used for such diverse applications as blood transfusion tubing capable of sterilisation, antibiotic container closures, electric iron gaskets, domestic refrigerators and non-adhesive rubber-covered rollers for handling such materials as confectionery and adhesive tape. The cold-curing rubbers are of value in potting and encapsulation. 

It is very simple to perform batch fermentation in a small flask with a volume of say 200 ml. Now our target is to use a 2 litre B. Braun fermenter. All accessories are shown in Figure 10.5. The fermentation vessel only, as shown in Figure 10.6, with about 250 ml of media without any accessories but with some silicon tubing attached with a filter for ventilation is autoclaved at a 131 °C for 10 minutes at 15psig.9 After that, the system is handled with special care and all accessories attached. Media is separately sterilised and pumped into the vessel. Inoculum is transferred and the batch experiment is started right after the inoculation of seed culture. An initial sample is withdrawn for analysis. 

To clear slant tubes, culture agar solution is prepared. To have clear agar solution, it has to boil. Agar is a polysaccharide. It is not soluble in cold water, so heating helps to dissolve it in water. Once the solution is dispensed in the tube, it goes for sterilisation. Agar is in the solid state at room temperature, about 35 °C. 

Electron beam sterilisation is a high-voltage potential established between a cathode and an anode in an evacuated tube. The cathode emits electrons, as a cathodic ray or electron beam. A high intensity of electrons is produced. These electrons are accelerated to extremely high velocities. These accelerated electron intensities have great potential as a bacteriocide. Most electron beams operate in a vacuum. As a result the unwanted organisms in the media vanish and the media is sterilised. 

Nylon can be sterilised with steam so it is sued in hypodermic syringes and surgical accessories. Curtain runners, sinks, zips, combs and switches are manufactured from nylon. Extruded nylon is used in covering wire ropes, in packaging film for pharmaceuticals, bottles, tubing, etc. Nylon laminates are used for heavy duty driving belts. Monofilaments are used in brushes, sports equipment, surgical sutures, etc. Monofilaments are prepared from nylon 6, 10 or nylon 11. 

However, this does not necessarily apply to foods which heat by convection. Jowitt quotes both peas in brine and soup as examples where the process time was doubled in a fluidized bed (22 minutes) compared to a steam-heated retort (11 minutes) for the same total process lethality. However, increasing the fluidized bed temperature by 8K resulted in almost equal process times and approximately equal retention of the heat-sensitive vitamin thiamine. Following the heating and holding stages of the sterilisation operation, the cans were cooled in a fluidized bed in which heat was removed by cooling water passed through finned tubes immersed in the bed (Jowitt and Thorne, 1971). 

There are a number of well-established systems for the aseptic packaging of liquids. Notable among these are those packs constructed, box form, in situ on the filling line from a cardboard, aluminium, plastic laminate sheet, such as TetraPak or Combi-box. In the TetraPak system, the packing material enters the filling machine from a feed roll the sheet contact surface is sterilised with warm hydrogen peroxide solution it is formed into a tube, and its lower end is heat-sealed across the width the tube is filled, sealed at the upper end, cut and then folded into a box shape. This produces a continuous output of filled cartons with premium utilisation of bulk storage capacity. 

Harvesting is continuous and under aseptic conditions, with medium recycle without re-sterilisation. Residual nutrients are monitored to ensure there is no build up (for example of phosphate). Hie cream (biomass) from flocculation and centrifugation is adjusted to normal pH (remember it was acidified for flocculation), then dried in an downstrsam air-lift flash drier. Forthis thecreamis fed into the venturi of the drier tube and is carried... 

Semi-solid products have been traditionally packed in collapsible tin tubes. Metal tubes are a potential source of metal particles in ophthalmic products, and so the tubes have to be cleaned carefully prior to sterilisation. Also, the final product must meet limits for the number of metal particles found. Plastic tubes are not suitable because of their non-collapsible nature, which causes air to enter the tube after withdrawal of each dose. However, collapsible tubes made from laminates of plastic, aluminium foil and paper are a good alternative to tin tubes. Laminated tubes fitted with polypropylene caps can be sterilised by autoclaving, whereas tubes fitted with polyethylene caps are sterilised by gamma irradiation. The tubes are usually filled aseptically, sealed with an adhesive and then crimped. 

Chemical indicators are available for heat, ethylene oxide and radiation sterilisation, usually in the form of adhesive tapes or patches, colour spot cards, small tubes or sachets. They change colour as a result of chemical reaction brought about by the sterilisation process, but it is possible for the change to take place before the sterilising time has been completed, and hence, with the exception of plastic dosimeters used in radiation sterilisation, they are unsuitable as proof of sterilisation. 

Heat is frequently used to sterilise or pasteurise the tubes before addition of the inoculum, but causes problems if the vitamin is not heat stable. In this case, membrane filtration may be used, and the vitamin preparation added aseptically to tubes of sterile medium. These procedures again imply a considerable level of microbiological expertise and competence. 

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