PPM Blog

“Flash” pasteurization is a process that brings the product up to a certain temperature very quickly and then cools it very quickly. It is based on the idea you don’t need to “cook” a product for a long time in order to successfully kill the organisms. Rather, if you just expose the organism briefly to its worst heat, it will die and the product flavor won’t change significantly.  The trouble with “flash” pasteurization is that it is intended to achieve a “5-log kill step.” If for some reason, · the product heats unevenly OR the equipment doesn’t work right OR the strain of organisms is more heat resistant OR the product has different levels of acidity, sweetness, etc. flash pasteurization is more likely to end up with contamination than other forms of pasteurization, specifically because the margin for error is smaller. Likewise, though FDA is trying to validate different methods of pasteurization and organism reduction, the reality is that these new methods of pathogen-reduction are not necessarily all backed by unbiased government science with the organism in the product that is being made. 

High-Level Disinfection with Hot Water Pasteurization 

  Pasteurization is a process that destroys microorganisms in a liquid medium by application of heat. Louis Pasteur first applied this process to wine making to prevent microbial spoilage, and pasteurization is currently used for the preservation of milk and many other food products. Pasteurizing temperatures in the range of 55–75°C will destroy all vegetative bacteria of significance in human disease, as well as many fungi and viruses. 

The PPM Batch Pasteurizer is capable of a programmed thermal ramp where the temperature change per unit time is programmed and also a dwell time at a specific pasteurization temperature is programmed. This flexibility in conjunction with a dense spray assembly assures complete pasteurization of each and every batch. The bottles or jars are fed in on the powered conveyor filling the unit to capacity. Thereupon, the doors are closed and the process begins. Heated water is sprayed over the containers heating them evenly and thoroughly. The containers temperature is ramped up at a rate which is safe for the glass containers. When the pasteurization temperature is reached, this temperature is maintained for the duration of the dwell time after which the containers are cooled at a rate which is also safe for glass. When the final chilled temperature is reached the machine shuts down and is ready for unloading. The same powered conveyor feeds the bottles or jars out. After unloading is complete the unit is ready for another batch.   

The PPM Tunnel Pasteurizer is made up of a number of modules (zones) each with its own pump, spray assembly, heat exchanger and temperature controller. The speed of the conveyor belt in conjunction with the heated spray assemblies determines the rate of heating of the containers. The temperature ramps up within each zone and also from zone to zone until the pasteurization temperature is reached. It then maintains this temperature for the proper dwell time after which the cooling cycle begins. All of this happens on a continuous basis as the containers are moving through the pasteurizer on the conveyor belt. The tunnel pasteurizer has the greater potential for speed between the batch pasteurizer and the tunnel pasteurizer.                         

VACUUM CALCULATIONS FOR EVACUATION
AND THE DIFFERENCE BETWEEN A LIQUID RING
VACUUM PUMP AND A VENTURI VACUUM PUMP
 

Q=V x Ln (P1/P2)
Where:
Q = Total amount of air to be removed
V = Volume of reservoir plus connecting pipe in cuft
P1 = Initial absolute pressure in Torr (mmHg A)
P2 = Required absolute pressure in Torr
Ln = Natural logarithm
 

Let’s use six 12oz bottles as our volume which in this case would equal 6×13oz=78oz = .081 cuft
Atmospheric pressure in Torr is 760
25” of Vacuum = 120 Torr
760/120=6.333
Ln 6.333=1.846
1.846 x .081 = .149 cuft/min
We want to evacuate the bottles in 1 sec therefore we multiply by 60
.149 x 60 = 8.97 cuft / min
 

Basically we need a vacuum pump capable of approximately 10 ACFM
 

Most single stage, liquid ring vacuum pumps with a 1-1/2 HP motor are capable of 10 ACFM.
 

As the following specifications plainly show a venturi vacuum pump is totally unsuitable for this application. At 24” of vacuum the maximum flow that can be achieved is 4.5 SCFM. And this flow requires 28 SCFM of air at 80 PSI. That is essentially a 10 HP Compressor.
 

That means it would take a 20 HP compressor and two venturi vacuum pumps to almost achieve what a liquid ring vacuum pump with a 1-1/2 HP motor achieves. And obviously, anything less will certainly not do the job.
 

The carbonated beverage filler is properly called a Counter Pressure Filler. It’s called a counter pressure filler because in order to transfer a carbonated beverage from a holding tank (also called a surge tank) to a container, the container must first be pressurized. The basic process for transferring a carbonated beverage from a surge tank to a container is:
Seal on the container opening
Charge the bottle with carbon dioxide to the surge tank pressure.
Transfer the beverage from the surge tank to the container by gravity.
Relieve the pressure in the container to atmospheric pressure.
Un seal the container.
 

These are the basic steps required for filling a container with a carbonated beverage. However, most modern day counter pressure fillers have been enhanced to include double pre-evacuation and inert gas leveling. Most carbonated beverages are negatively affected by oxygen. If there is oxygen present in these beverages it will, in a very short time change the flavor profile of that beverage. Double pre-evacuation is a process whereby oxygen is removed from the container to prevent this from happening. This process removes 99.9% of the oxygen present in the container when it enters the filler. Inert gas leveling is the process whereby the container is overfilled with product after which the excess is pushed out utilizing a higher pressure inert gas (CO2, Nitrogen) than the counter pressure. This provides for very precise fill heights as well as accurate fill amounts in the container.
 

There are basically two configurations of counter pressure filler. A rotary configuration and an in-line configuration and each has its benefits and its shortfalls. The rotary filler in general is faster primarily because of the large number of valves. However, there are costs associated with this speed. The first cost is the fact that when something goes wrong a large number of containers are lost because the machine cannot be stopped immediately. It must be brought to a stop through a number of revolutions resulting in the loss of those bottles filling at the time.  Another cost associated with the rotary filler is the fact that its time functions ( pre-evacuation, CO2 charge, snift) are all based upon hard cams and an ideal speed. In other words, there is only one speed that a rotary travels that has the correct operating times. At every other speed, the times are different. Another cost is complexity. The rotary is by its very nature a much more complex (and expensive) machine. Another cost is associated with its higher speed. In order to operate a rotary at its optimum speed (obviously, there is no point in getting a rotary and then running it slowly, this would defeat the whole purpose of getting a rotary in the first place) a great deal of support must be provided. This support can be in the form of automated equipment such as un-casers, single filers, case packers and automatic palletizers (at great additional expense) or it can be in the form of labor (a great deal of it but only when operating the filler). There is another benefit to the rotary filler. The time between filling and capping or crowning is very short.
 

The in-line filler is limited in the number of valves it can accommodate. This limits its speed. There is also a time delay between filling and capping or crowning. This is only important for those fillers without double pre-evacuation and a fobber for those products sensitive to oxidation. A little explanation is in order here. Double pre-evacuation assures extremely low dissolved oxygen pickup in the product and a fobber assures that the headspace air is expelled prior to capping and assures “capping on foam”. The two together assure that each bottle of product will have maximum shelf life without oxidation affecting the flavor profile. The benefits of an in-line are its simplicity (low cost) and its flexibility. It can be made to accommodate a large range of container types and sizes. It can be made expandable by adding valves as the need arises. Another benefit is its adjustability of function times such as pre-evacuation, CO2 charge, snift. These times once set, repeat time after time after time. This means that the machine operates with all function times set at optimum, permanently. And if there is a reason to change one or more of the function times, this can be accomplished while the machine is operating. However, that’s not all. There are functions which can be added to an in-line which cannot be added to a rotary such as a pre-snift pause. Some times it is necessary to run product that is not at the optimum operating temperature. When this happens the product often wants to foam over causing “short fills”. A pause prior to snifting will often calm the product and prevent this foaming. And if something should go wrong, an in-line can be stopped at anytime during a cycle with very little lost product.
 

There are some subtleties involved in carbonated filling. The product temperature should be as close to freezing as possible but should not be freezing. The CO2 flow rate should be capable of very high volume or a buffer tank should be installed between the CO2 source and the filler surge tank.