Sterilization time

Ethylene oxide Gas concentration 800-1200 mgl 45-63°C 30-70% relative humidity 1-4 hours sterilizing time... 

Low-temperature steam and formaldehyde Gas concentration 15-100 mgl" Steam admission to 73°C 40-180min sterilizing time depending on type of process... 

Nakahari [2.11] describes, on the basis of his experience with VHP , the advantages of this process a short sterilization time at room temperature, the possibility to update existing plants, VHP does not - compared with ethylenoxide and formaldehyde - affect the health of the operators and can be decomposed to water and 02 without contaminating the atmosphere. 

Sterilization time Sterilization temperature Drying time... 

Study No./Batch No. Date Set Temperature Sterilization Time... 

It can be operated at a high temperature (140°C instead of 121 °C in batch sterilization) therefore, the sterilization time can be shortened (holding time of 1 to 2 minutes). 

Deindoerfer, F. H. and A. E. Humphrey, "Analytical Method for Calculating Heat Sterilization Time," Appl. Micro. 7 (1959a) 256 - 264. 

Lessons may also be learned from applications of control systems in the food processing industries. These applications must satisfy hygiene requirements (including periodic cleaning and sterilization), time constraints imposed by product perishability, and requirements for accurate records of sources and operation histories of materials.21 The industry also experiences slim profit margins, short production runs, and frequent product changeovers—characteristics shared with many industrial bioprocesses. 

In estimating the sterilization time for the medium, one must define the contamination, the desired degree of apparent sterility, and the time-temperature profile of the medium that is, T = f(t). For typical bacterial spore contaminants, the constants used in most designs have the following values. 

To sterilize heat-sensitive products at high temperature, drastically reducing the sterilization time. The logic behind this principle is that, as... 

Batch sterilizing in fermenters is frequently a problem because the slow agitation speed is not adequate to keep all the suspended material equally dispersed. Some may settle out in poor circulation areas of the vessel some materials may enter the air ring while filling the vessels. Solutions to these problems can be prehydrolyze the starch or protein with enzymes use a longer sterilizing time or higher temperatures use a continuous sterilizer (abandon batch sterilization). 

When the contamination must be reduced to one in 1000 fermentations, estimate the required sterilization time. 

Slightly sol in ether. Natural pH about 9.5. Reasonably stable to usual sterilization time and temp in aq solns adjusted to pH 3.0 -4.0, but long heating causes racemization. Hydrolyzed by alkali and strong acid. Usually more stable than salts of pantothenic acid if pH can be adjusted between 3 and S. For add stability data see Rubin, J. Am. Pharm. Assoc.. ScL Ed. 37, 502 (1948). Aq solns can be stabilized with pantolactone US. pat. 2,898,373 (1959). df-Form, panthenol. 

Sufficient time must be allowed for the whole of the load to reach the required temperature before measurement of the sterilizing time is started. This time must be determined for each type of load to be processed. 

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

Note that the effect achieved from sterilizing at 60 minutes at 15 psi is the same as that from 30 minutes at 30 psi. Hence a doubling of pressure reduces sterilization time by one half. Most pressure cookers can not be safely operated at this level unless carefully modified according to the... 

Most microorganisms are killed in the sterilization process. For liquids, the standard time and pressure for steam sterilization is 25 minutes at 15 psi (250 ° F. For solids such as rye, the sterilization time must be increased to insure that the steam sufficiently penetrates the small air pockets and structural cavities in the grain. Within these cavities bacteria and other thermo-resistant organisms, partially protected from the effects of steam, have a better chance of enduring a shorter sterilization period than a longer one. Hence, a full hour at 15 psi is The minimum time recommended to sterilize jars of rye grain. 

Szarka and Magyar [24] investigated the foaminess of various cultivation mediiun components such as corn-steep liquor, peanut meal, soybean meal and casein solutions and their dependence on the pH value and steriUzation. The foaminess passes a maximum with increasing concentration of these components in the range 3 to 5% and as a function of the pH value. The maximum is at pH 4 in the case of soybean meal solutions. With increasing sterilization time the foaminess is enhanced. After 100 min heat treatment at 125°C, the foaminess 2 increased by a factor of 7 in the case of a model cultivation mediiun consisting of glucose soybean meal and CaCOj in water. 

The culture medium is heated up in circulating steam at 100 °C for a sterilizing time of 30 minutes on three consecutive days. Between the individual heating periods, the culture medium is incubated at about 25 C. When the culture medium is heated up to 100 C, the vegetative cells are killed. Spores of bacteria and moulds, however, survive a single treatment at 100 °C. This is why the intermediate periods of incubation are introduced. Vegetative forms develop from the steam-resistant spores and these are then killed by the subsequent heating period. The heat treatment is carried out three times to increase the reliability of the process. 

Nakahira [11] describes his experience with the modification of an existing plant to use the sterilizing process in equipment that cannot be steam sterilized. The advantages were update of an existing plant, short sterilization time at room temperature, and compared with ethylenoxide—no risk to the operators and no contamination of the environment. 

Many of the techniques used by chemical engineers are also helpful in the food processing industry. For example, consider the problem of sterilizing food after it has been placed in cylindrical cans. Normally, it is assumed that all harmful bacteria will be killed if the food temperature is raised to some value T], The heating process is accomplished by placing the can in a sterilization bath that is maintained at a high temperature Tq. Develop an equation for the sterilization time. Also, by selecting various values for the... 

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