EXPERIMENTS ON THE SPOILAGE OF TOMATO KETCHUP TEXT

storage by the two methods is not very great, and some large concerns are using the can exclusively instead of the barrel. LABELS. The labels on the ketchup bottles have been improved somewhat in the last year as regards exactness in describing the contents. Formerly, according to the labels, much of the ketchup was made from whole ripe tomatoes. The question was, What became of the enormous amount of ketchup which it was known had been made from “trimmings?” On this year’s ketchup the labels make fewer claims, generally merely stating that it is “tomato ketchup,” which is true whether made from whole tomatoes or refuse. The brand is in most cases the guaranty for good quality. It is not safe to judge the quality by the price, for, though usually good quality can not be expected unless the higher price is paid, some of the high-priced ketchup when placed under the microscope has proven to be a very inferior product. The wide labels on the neck of the bottle are objectionable. Some of these are 2 inches in height, and serve to cover the discolored and spoiled ketchup. As spoilage begins usually in the neck of the bottle, it is difficult to see it when the neck is wrapped with a label, and thus it might easily be overlooked until the main body of the ketchup is affected. The bottles which have the widest labels around the neck are usually the ones provided with one or two large labels on the lower part of the bottle, though some bottles have no other label but the one around the neck. As a rule, however, these are narrow, close to the stopper, and unobjectionable. In buying ketchup for experimental purposes it was difficult and sometimes impossible to learn its age, as often the grocer does not know it, and at other times he will not tell. It appeared, however, that often the ketchup had been on the grocer’s shelf or in the warehouse from one to four years. MANUFACTURING EXPERIMENTS WITHOUT THE USE OF PRESERVATIVES. OUTLINE OF THE EXPERIMENTS. During September, 1907, ketchup was made in experimental batches to determine whether it could be manufactured on a commercial scale without the use of preservatives. These experiments were made to determine (1) the keeping quality before opening the container and (2) the length of time the product will keep without spoilage after the bottle is opened. The ketchup was made in a factory in which the conditions of manufacture and all the surroundings were sanitary; whole, ripe tomatoes, the same as used in the regular grade of canned goods, were used and the formula and process were for a mild ketchup giving the maximum of tomato flavor. Each batch consisted of 50 gallons of finished goods, from which 1 gross of pint bottles was retained for observation. The term “regular ketchup” as used in these experiments means the pulp of fully ripe tomatoes, to which was added granulated sugar, 80-grain, distilled vinegar, table salt, onions, garlic, whole cinnamon, cloves, mace, and ground cayenne pepper. The pulp was cooked in a steam-jacketed copper kettle for forty minutes and reduced about 50 per cent. The finishing was done after cooking. The regular bottles are pint sizes, washed in hot water, rinsed, and then heated to a temperature of 190° F. for thirty minutes or more. The sterile bottles referred to in the experiments were placed in a steam chamber for twenty minutes at 230° F. The corks were sterilized by a bath in paraffin at about 270° F. All of the work was accomplished quickly to insure a smooth, even product with a bright, clean color. Acetic acid extracts and oil extracts of spices were used in such quantities as would give the same amount of spicing as when the whole spices were employed. In all of the following experiments the ketchups discussed were made in September, 1907, and the last examination reported was made ten months later, in July, 1908: _Experiment No. 1._--Regular ketchup was made, but it was reheated after finishing and bottled in sterile bottles at a temperature of 205° F. No spoilage has occurred at the end of ten months. _Experiment No. 2._--Regular ketchup was made, and it was bottled immediately after finishing in regular bottles at a temperature of 165° F. An after process was given at 190° F. for twenty minutes. No spoilage has occurred after ten months. _Experiment No. 3._--Regular ketchup was made, and was bottled in regular bottles at 165° F., and given a subsequent process at 190° F. for forty minutes. No spoilage has occurred. _Experiment No. 4._--Regular ketchup was made, was bottled in regular bottles at a temperature of 165° F., and given an after process at 212° F. for twenty minutes. No spoilage has occurred. _Experiment No. 5._--Regular ketchup was made, the same being put up in regular bottles at a temperature of 165° F. and given an after process at 212° F. for forty minutes. No spoilage has occurred. _Experiment No. 6._--Ketchup was made in which the acetic acid extracts took the place of whole spices, and the bottling was done at a temperature of 165° F., no after treatment being given. No spoilage has occurred. _Experiment No. 7._--Ketchup was made in which acetic acid extracts were used, and the bottling was done at a temperature of 165° F. in sterile bottles. No after treatment was given and no spoilage has occurred. _Experiment No. 8._--Ketchup was made in which the oil extracts were used instead of regular spices. The bottling was done in regular bottles at a temperature of 165° F., no after treatment being given. No spoilage has occurred. _Experiment No. 9._--Ketchup was made in which oil extracts were used instead of whole spices. The bottling was done at 165° F. in sterile bottles, no after treatment being given. No spoilage has occurred. _Experiment No. 10._--Regular ketchup was made, but the pulp was run through the sieving or finishing machine before instead of after cooking, the object being to determine the effect upon the character of the goods rather than upon the spoilage. This practice could be followed to advantage in making all except the very finest goods, and would give the same condition for bottling as in experiment No. 1. _Experiment No. 11._--Pulp was made in the usual manner and run into barrels while just below the boiling point. The barrels had been thoroughly washed and then steamed for twenty minutes. As soon as the pulp had cooled slightly the bung was driven in tightly and the barrel was rolled into storage. At the end of sixty days the barrels were opened and the pulp was found to be in good condition. _Experiment No. 12._--Regular ketchup was drawn into 5-gallon jugs which had been sterilized in the same manner as the bottles. These were kept for sixty days and no spoilage occurred. DISCUSSION OF RESULTS. Twelve hundred and ninety-six bottles were shipped from Terre Haute to Lafayette, Ind., and some were reshipped in order to duplicate the conditions in trade. Some were kept in a warm temperature and in strong light, others in a comparatively cool place and in the original shipping cases, in order to duplicate the conditions in the warehouse and grocery store. There has been no spoilage after ten months other than that resulting from four or five cork leaks and neck cracks. These experiments have shown conclusively that ketchup can be put up on a commercial scale and delivered to the consumer in perfect condition without the use of a preservative. It was demonstrated by the first experiment that the goods could be bottled at a high temperature without difficulty, and that subsequent treatment was unnecessary. The after treatment at 190° was tried because it had been found in small experiments that, in giving a higher temperature, the internal pressure would cause more or less breakage of bottles or loosening of corks. After treatment is practiced by some who also use a small quantity of preservative as a further precaution. This treatment is continued from two to three hours at the temperature of high pasteurization. The process at 212° was given with little breakage, as the bottles used were of good quality. At and above this temperature the breakage may be reduced by either raising the temperature of the ketchup before bottling or applying pressure upon the outside while giving the process. Neither the acetic acid nor the oil extracts showed any advantage over whole spices in their preservative effects, as all kept. The color was slightly improved, but the flavor was impaired, particularly when the oil extracts were used. SPOILAGE OF KETCHUP AFTER OPENING. The question of how long the ketchup should keep after opening the container in order to satisfy the ordinary requirements of consumption was also studied. A local restaurant, serving about two hundred meals and using from one-half to a gallon of ketchup daily, was supplied with the same kind of ketchup used in the experiments, as were also some families. Instructions were given to use the ketchup as they would ordinarily, with the result that none reported any loss from spoilage. To determine how long the ketchup would keep after opening, 8 bottles from each of the first 9 experiments were kept in the kitchen at a temperature of about 72° F., 5 were kept in an incubator at a temperature of 95° F., 5 were kept in the laboratory at a temperature of about 67° F., and 4 were kept in an inclosed porch where the temperature ranged from 30° to 60° F. This made a total of 198 bottles. No precautions, other than those of ordinary cleanliness, were taken in opening the bottles, as it was desired to determine the keeping properties under conditions of general usage. The first set of bottles was opened November 5, immediately on being received at the laboratory, all of the ketchup having been kept at the factory until the experiment begun in September was completed. The bottles were covered loosely with a metal cap and observed daily, a record being kept of the date and character of spoilage. The results showed that the differences in the time and temperature of processing had little, if any, effect in checking the spoilage; neither did the use of acetic acid or oil extracts. The most important precaution in checking the spoilage after opening seems to be to keep the ketchup cool. This is shown by the average number of days which elapsed before spoilage occurred in the sets kept under different temperature conditions. For those kept in the kitchen the average number of days was six, the minimum three, and the maximum eleven. Those in the incubator kept for an average of five days, with a minimum of two days, and a maximum of eight. Those in the laboratory had an average of eight days, the minimum being four days and the maximum twenty-two. Those kept in the porch lasted on an average twenty-seven days, a minimum of twelve days, and a maximum of fifty-eight. These figures show the definite relation of temperature to spoilage under the conditions of ordinary use. In making the observations, the metal cap was removed each day, but no ketchup was poured off. The spoilage in all cases was due to mold, and usually this formed in the neck of the bottle where the ketchup had splashed, or at the junction of the ketchup with the bottle. The spoilage was recorded as soon as the slightest growth appeared. In actual use if the neck were wiped out when the ketchup had been used and a growth of mold removed on its first appearance with some of the proximate ketchup the time before spoilage occurred could be prolonged. In these experiments the attempt was made to determine how soon growth appeared under the various conditions of temperature named. The unopened bottles of ketchup were kept in a basement room, the temperature of which is fairly constant, being about 70° F. This is approximately the condition in a grocery where the ketchup is kept on the shelves. Another set of samples from the run of September, 1907, was opened February 11, 1908, to determine if storing in a warm room before opening had any effect on the length of time preceding spoilage. Four bottles were taken from each of the first 9 experiments to make up each of three sets, one of which was kept in the kitchen, one in the incubator, and one in the porch, making a total of 108 bottles. The average number of days for those kept in the incubator was four, the minimum two, and the maximum six. The average number of days before spoilage in the kitchen was five, the minimum being three and the maximum nine. Those kept in the porch gave an average of twenty-three days, the minimum number being eighteen days and the maximum seventy-three days. Thus it is seen that the ketchup lasted nearly five times as long at a temperature of 30° to 60° F. as it did at 72°; and also that when ketchup is kept in a warm place before opening, spoilage occurs somewhat sooner, the average for the fresh samples opened under the same conditions being one day more with the incubator and kitchen samples and four days more with the porch samples. A third set of bottles of the ketchup was opened on June 6, 1908, or two hundred and sixty-five days after manufacture. They had been kept in a basement at a temperature of about 70° F. One set was placed in the incubator at a temperature of 95° F., one set in the kitchen at about 82° F., and one set in the refrigerator at 46° F. The weather was warm and the conditions favorable to the spoilage of fresh foods. The minimum time for spoilage in the incubator was two days, the maximum time four days, and the average time three and two-tenths days. The minimum time in the kitchen was two days, the maximum time six days, and the average time four and four-tenths days. The minimum time in the refrigerator was nine days, the maximum time nineteen days, and the average time thirteen and sixty-six one-hundredths days. These data are grouped in the following table for easier comparison: _Time of spoilage of ketchup at different temperatures after opening._ OPENED ON NOVEMBER 5, 1907, IMMEDIATELY UPON RECEIPT FROM FACTORY; MAXIMUM AGE, FIVE WEEKS. ----------------------------------------------------------------- Place of storage. | Temperature. | Lapse of time before spoilage. | |------------------------------- | | Average. | Minimum. | Maximum. ------------------| |----------+----------+--------- | _° F._ | _Days._ | _Days._ | _Days._ Incubator | 95 | 5 | 2 | 8 Kitchen | 72 | 6 | 3 | 11 Laboratory | 67 | 8 | 4 | 22 Porch | 30-60 | 27 | 12 | 58 ----------------------------------------------------------------- KEPT AT 70° F. FOR ONE HUNDRED AND FIFTY DAYS BEFORE OPENING ON FEBRUARY 11. ----------------------------------------------------------------- Incubator | 95 | 4 | 2 | 6 Kitchen | 72 | 5 | 3 | 9 Porch | 30-60 | 23 | 18 | 73 ----------------------------------------------------------------- KEPT AT 70° F. FOR TWO HUNDRED AND SIXTY-FIVE DAYS BEFORE OPENING ON JUNE 6. ----------------------------------------------------------------- Incubator | 95 | 3.2 | 2 | 4 Kitchen | 82 | 4.4 | 2 | 6 Refrigerator | 46 | 13.66 | 9 | 19 ----------------------------------------------------------------- SPOILAGE OF UNOPENED KETCHUP. Another test was made to determine whether the ketchup would spoil when kept in a warm place, but not opened. Three bottles from each experimental batch were placed in the incubator November 7, 1907, and were kept there until December 23, 1907--forty-six days--and in that time there was no sign of spoilage. They were then opened and kept in the laboratory; the average number of days before spoilage occurred is indicated in the following table: _Average number of days before spoilage of ketchup after opening (kept 46 days at 95° before opening)._ --------------------------------------- Experiment No. | Days before spoilage. ---------------+----------------------- 1 | 2⅔ 2 | 4⅔ 3 | 3⅓ 4 | 5 5 | 5⅓ 6 | 4⅓ 7 | 4⅓ 8 | 4⅓ 9 | 3⅔ --------------------------------------- It will be observed that these samples spoiled in about the same length of time as the bottles opened in February and tested in the incubator, so that similar results were obtained by keeping unopened ketchup one and one-half months at 95° F. and keeping it five months at 70° F. From the results of the experiments it is evident that the ingredients of the ketchup in the proportions used are not antiseptic, and it is also apparent from the number of organisms found and the rapidity of their multiplication that ketchup is a good, nutritive medium. Yeasts and molds are the predominating organisms, and, as the ketchup is acid and also contains sugar, and these organisms are found on tomatoes in the field, their predominance in the ketchup is explained. SPOILAGE OF MARKET BRANDS. To determine the keeping properties of the ketchup on the market, various brands were obtained from the grocery stores. In the majority of cases nothing was known of the ingredients or methods of manufacture, except what appeared on the labels. No date of manufacture was given, and in some cases the dealers did not know the age of the product. There were 104 bottles of ketchup opened to find out how long they would remain in good condition. These were kept in the laboratory, though the temperature was higher than that at which ketchup should be held. Of the 104 bottles there were 66 without preservative, according to the labels, 46 of which spoiled. Of the 20 which did not spoil, 2 formed crystals of benzoic acid on the covers of glass dishes during evaporation. Of the 39 which, according to the labels, contained sodium benzoate, 15 spoiled. The bottles of unspoiled ketchup after remaining in the laboratory for about a month were placed in the incubator at 95° F. for three weeks, and were then taken out, and have been left in the laboratory since. The metal cap had been taken off frequently for observation, and the ketchup exposed, but the treatment did not cause them to spoil. The average number of days after which spoilage occurred for the 46 bottles without preservative was about fifteen, the minimum number being four days, the maximum number ninety-four days. The average number of days preceding spoilage in the case of 15 bottles with preservative was twenty-four days, the minimum number being three and the maximum sixty days. The majority of these had 0.1 per cent of sodium benzoate present; the others had a smaller amount, according to the manufacturer’s label. These data are not at all conclusive and further work on material of known history will be necessary. STERILITY OF KETCHUP. To determine the sterility of ketchup, cultures were made from 77 of the bottles. The method used was to wipe the bottles and cork stoppers with a damp towel and then remove the cork. The cork puller which was used grasps the neck of the bottle in such a way as to cover the opening and remove the cork without the inrush of air that occurs when