Heat sterilization operation

Where floor drainage channels are necessary they should be open if possible, shallow and easy to clean. Connections to drains should be outside areas where sensitive products are being manufactured and, where possible, drains should be avoided in areas where aseptic operations are being carried out. If this cannot be avoided, they must be fitted with effective traps, preferably with electrically operated heat-sterilizing devices. 

Fixed thermocouples shall be located at key sterilizer positions, as justified by the sterilizer operation and control characteristics (i.e., at exhaust or vent line, in recirculation heating medium line, next to controller sensor, as applicable). 

Dry heat sterilization validation. The tunnel operations conform to the master validation plan employed at ABC Pharmaceutical Industries. The sterilizing tunnel has undergone installation qualification, operational qualification, and performance qualification. The sterilizing tunnel is revalidated on an annual basis. The sterilization/depyrogenation cycle revalidation data for the tunnel are provided in validation archives. Sterilization validation reports are provided in validation archives. 

Among the techniques discussed, moist heat is the most economical and efficient for the general sterilization requirements of fermentation. Therefore, the following four sections describe cell death kinetics and sterilization operations utilizing moist heat. 

Parenteral Drug Association. Moist Heat Sterilization in Autoclaves Cycle Development, Validation and Routine Operation. PDA technical report 1, revision, draft 11. Bethesda, MD, May 2001. 

Common unit operations of food processing are reported to have only minor effects on the carotenoids (Borenstein and Bunnell 1967). The carotenoid-protein complexes are generally more stable than the free carotenoids. Because carotenoids are highly unsaturated, oxygen and light are major factors in their breakdown. Blanching destroys enzymes that cause carotenoid destruction. Carotenoids in frozen or heat-sterilized foods are quite stable. The stability of carotenoids in dehydrated foods is poor, unless the food is packaged in inert gas. A notable exception is dried apricots, which keep their color well. Dehydrated carrots fade rapidly. 

If an effective dry heat depyrogenation is performed, sterilization generally is achieved as well. Effective dry heat sterilization can be performed even without achieving depyrogenation. If moist heat sterilization is performed, in normal operating conditions depyrogenation is not achieved. 

All pharmacopeias consider moist-heat sterilization as the method of choice, i.e., the method to be preferred, unless, of course, the product to be sterilized is incompatible with the characteristics of steam. The reason for this preference is the fact that moist-heat sterilization provides the best combination of flexibility, reliability, and low equipment and operating costs. 

Moist-heat autoclaves operating with counterpressure are sterilizers capable of controlling the pressure of their sterilizing medium independently of its temperature. They are used essentially for the terminal sterilization of solutions. 

Relatively stable substances that resist degradation at high temperatures (>140°C) are suitable candidates for dry heat sterilization. A 2-h exposure at 180°C or 45 min at 260° C kills spores as well as vegetative forms of micro-organisms. These exposure periods do not include the lag time from loading of the oven until sterilization temperature is reached. The lag time depends on the geometry and operating features of the oven and the characteristics of the load. 

Many other liquid characteristics must be considered by the designer of an evaporator. Some of these are specific heat, heat of concentration, freezing point, gas liberation on boiling, toxicity, explosion hazards, radioactivity, and necessity for sterile operation. Because of the variation in liquor properties, many different evaporator designs have been developed. The choice for any specific problem depends primarily on the characteristics of the liquid. 

Direct methods of measuring gas concentration include gas chromatography and infrared spectroscopy. Both methods are dependent upon small samples, and the problems of drawing these samples should not be underestimated. The location of multiple sample pons should be such that a representative sample of a hopefully homogeneous gas mixture is obtainable. With most sterilizers operating at positive pressures, it is not usually necessary to have any special means of withdrawing the gas, but it is essential to have sample lines heated and insulated to avoid condensation of gas and water between the sterilizer and the analytical instrument. 

This method is slow because of the multiple operations on a shuttle machine. The heat of extmsion sterilizes the bottle, which is not readily achieved after molding. Blow-mold/fill/seal systems are used commercially for beverages and for pharmaceutical packaging. 

The most widely used sterilization method ia the food industry is moist heat. The heat is usually suppHed by high pressure steam, but because most foods already contain moisture the role of steam is to heat the food to the required temperature. The cooking and sterilization processes can frequendy be combined into one. The food may be sealed into impervious containers of glass, metal, or plastic film and undergo terminal sterilization, or it may be presterilized in batches or in a continuous operation and then filled into a presterilized container. The latter process is called sterile filling. 

Often batch process equipment needs to be located inside buildings. This is usually the case when the process needs to be shielded from extreme heat/cold conditions, the elements, and/or needs to be kept sterile. This leads to the need to provide adequate building ventilation to avoid buildup of hazardous material due to leaks and other process emissions. When the operation of a process involves opening, cleaning, charging etc., point source ventilation may also need to be provided. 

---