Sterilization continuous flow

Coronel, P. and Simunovic, J. and Sandeep, K.P. and Cartwright, G.D. and Kumar, P. (2008). Sterilization solutions for aseptic processing using a continuous flow microwave system. Journal of Eood Engineering, 85, 528-536. 

Aseptic processing is used to achieve commercial sterility in a continuous flow of liquid or semi-liquid food by heating the food to a suitable temperature before placing it in previously sterilised packaging. The sterilisation of liquids containing particulates presents a number of... 

FIGURE 3.9 Circulating water photoreactor system for determination of photomicro-biocidal activity under water flow conditions, a, reinforced membrane used in the study b, water jacket, continuous flow, infrared filter c, light source d, air pump e, bacterial air filter f, 3-way tap/pressure release g, 2-way taps h, frit for aeration J, peristaltic pump k, reservoir 1, ground glass Joints for ease of cleaning and sterilization (Bonnett et ai, 2006). 

If it is necessary to refill the dispensing pressure vessel during filtration it is important that the pressure above the membrane filter does not fall or contamination may result. To avoid such a pressure fall valves may be fitted. Foot operated systems are available from Schleicher and Schuell which allow the flow of liquid to be interrupted at regular intervals this is very useful when filling 100 ml bottles from an otherwise continuous flow of 10 1 of sterile medium. However, we have found the system cumbersome to use and we... 

CONTINUOUS FLOW STERILIZATION Heat Transfer to Shear-Thinning Fluids... 

Chapter 8. Heat transfer in continuous flow sterilization and to canned foods under intermittent agitation. 

In an externally buffered enzyme electrode (Fig. 45), substrate-free buffer is continuously pumped between the dialysis membrane and the enzyme layer (Cleland and Enfors, 1984), i.e., the sample is diluted before it reaches the enzyme. The intensity of the buffer flow may be used to adjust the measuring range and sensitivity. The configuration of the sensor permits it to be sterilized. While the membrane is protected by continuously flowing buffer, the rest of the sensor can be sterilized for 1 h in a solution of 95% ethanol and 5% H2SO4. 

In sterilization of food in a container, the time required to render the material safe is calculated at the slowest-heating region of the container (usually the center). Other regions of the container are usually heated to higher temperatures and are overtreated. Hence, another method used is based on the probability of survival in the whole container. These details are given by others (C2, S2). In still another processing method, a short-time, continuous-flow process is used instead of a batch process in a container (B2). 

A safety cabinet is a laminar down flow cabinet, which is constructed specifically for protection of both the sterile product and the operator. It is frequently used in (hospital) pharmacies for aseptic preparation (when products are not fully closed) and for aseptic handling of class 4 or 5 substances (see Sects. 26.5.2 and 26.8). Laminar down flow has the advantage compared to cross flow that the operator does not feel the continuous flow in his direction. Other names for a safety cabinet are biosafety cabinet, biosafety bench, biohazard bench, biohazard cabinet, biological safety cabinet etc. 

In the holding section of a continuous sterilizer, correct exposure time and temperature must be maintained. Because of the distribution of residence times, the actual reduction of microbial contaminants in the holding section is significantly lower than that predicted from plug flow assumption. The difference between actual and predicted reduction in viable microorganisms can be several orders of magnitude therefore, a design based on ideal flow conditions may fail. 

A continuous fermenter with sterile feed is referred to as a chemostat. For constant volume operation, the inlet volumetric flow rate is equal to that at the output. With this model chemostat start-up, resultant steady state behaviour and cell washout phenomena are easily investigated by simulation. 

A medium is to be continuously sterilized at a flow rate of 2 in a ster-... 

A medium, which flows through an 80 mm i.d. stainless tube at a flow rate of 1.0 m h , is to be continuously sterilized by indirect heating with steam. The temperature ofthe holding section is maintained at 120 °C. The number of bacterial spores of 10 rn in the entering medium must be reduced to 0.01 m . The specific death rate of the bacterial spores in the medium, medium density, and medium viscosity at 120 °C are 180 h , 950 kgm , and 1.0kgm h , respectively. 

Two continuous stirred-tank fermenters are connected in series, the first having an operational volume of 100 1 and that of the second being 50 1. The feed to the first fermenter is sterile and contains 5000 mg/1 of substrate, being delivered to the fermenter at 18 1/h. If the microbial growth can be described by the Monod kinetic model with /x, = 0.25 h l and Ks = 120 mg/l, calculate the steady-state substrate concentration in the second vessel. What would happen if the flow were from the 50 I fermenter to the 100 1 fermenter ... 

A continuous sterilizer with a steam injector and a flash cooler will be employed to sterilize medium continuously with the flow rate of 2 m3/hr. The time for heating and cooling is negligible with this type of sterilizer. The typical bacterial count of the medium is about... 

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