As to the proper temperature, I do not see why as high a temperature as is possible without breaking the bottles should not be used. Why some packers process at 170 degrees or 180 degrees I do not know. They certainly have not carefully investigated the effect of their processing. The temperature I prefer is six degrees below boiling. At sea level this would be 206 degrees. This temperature will not break the bottles, but the steam pipes entering the tank should be so arranged and perforated that there will be as even a distribution of steam as possible. If these pipes are not properly arranged, there is apt to be as much as 6 degrees variation in the temperature at different parts of the tank.
Several years ago I made a large number of tests to determine the number of micro-organisms that remained alive in bottled catsup after processing at 206 degrees F., as compared with the number which remained alive in catsup bottled from the same batch and processed at 200 degrees F. for the same length of time. The difference was surprising. I expected some difference, but not nearly as great as was shown by the tests. That which was processed at 200 degrees for an hour contained quite a few living molds, yeasts, and bacteria per cubic centimeter. This was shown by plating out samples bacteriologically on culture media—the media used being dextrose agar and wart agar. The catsup from the same batch processed one hour at 206 degrees contained scarcely any living micro-organisms at all per cubic centimeter. This test was repeated a number of times with the same result each time. These micro-organisms may have been in the form of spores in the catsup, but developed into the vegetative forms of molds, yeasts, and bacteria when placed in the culture media.
Temperature Controlling and Recording Devices
The process tanks should all be equipped with temperature controllers and recording thermometers. The controller holds the steam at the right point, not allowing the temperature to vary more than 2 degrees, if it is a good make. Several years ago it was impossible to find a temperature controller which operated without compressed air that would hold the temperature closer than a variation of 10 degrees, which is too wide a variation for catsup pasteurization. The compressed air controllers worked very well but required an air compressor where the pressure must be held within certain limits, and air pipes to connect with all the controllers. Some plants did not have the air equipment, and in cases where it was put in the pipes gave more or less trouble due to the collection of moisture in them and to occasional grains of dust or rust from the air tank which lodged in the controller and threw it off. It is now possible, however, to obtain controllers which will operate with almost no variation from the temperature desired, and which require no compressed air for their proper functioning. Under these conditions there is hardly an excuse for a manufacturer to operate his plant on the old system of hand control of the steam valves, with the resulting losses in manufactured goods due to pure reliance on human efficiency.
The recording thermometer makes a pen and ink record on a chart showing the temperature and length of time each tank of catsup is given, or, if a continuous pasteurizer is used, it shows up any variations in the temperature of the water in that pasteurizer during the day. The factory manager can look at all of these charts in the morning, and know positively that every bottle of catsup was processed the right length of time, and at the right temperature. If any mistakes were made the chart will show it, and it will show at just what time the mistake was made, and how serious it was. It is a great satisfaction to have such a record, and the processor invariably takes great pride in making a perfect chart.
Non-Process Method
When no after-sterilization is given, it is imperative that the catsup be very hot when filled. Boiling catsup runs about 214 degrees F. in temperature, and although running it through the finisher and receiving tank cools it down somewhat, if it is heated in a long jacketed pipe while being conveyed from receiving tank to filling machine it should not be below 180 degrees at the very lowest when filled, and if it can be filled hotter than that, so much the better. As to the pipe above mentioned, the smaller the pipe, and the larger the steam jacket, and the higher the steam pressure, the greater will be the heating capacity of this jacket on the catsup. After a little experimenting these points can be adjusted to give the proper result. If the jacketed area is short, of course a higher steam pressure must be used than if this area is long.
Some packers of non-processed catsup use a jacketed tank or kettle directly over the filling machine to hold the catsup at a high temperature while it is awaiting bottling, with a very short line of enamel pipe going from it to the filling machine. If this is used, a jacketed pipe is not needed.
Guesswork should be eliminated. Do not assume that you are getting the right temperature on your catsup when it is filled, and do not be satisfied with going up to the filler once or twice a day, dropping a thermometer in the liquid, and waiting for the temperature to record itself. Put a recording thermometer in that tank just over the filling tubes, with the dial in a prominent place, so that you can step up to it at any time and know what the exact temperature of that catsup has been every minute of the time for the past ten or twelve hours.
If this is done there is no chance of escape on the part of the man who is supposed to watch this temperature, and if he knows his work is being recorded every minute on a chart he is going to be mighty careful.