SeDtember. 1930
INDUSTRIAL AND ENGINEERING CHEMISTRY
1015
Vitamins in' Canned Foods IX--Tomato Products b
E. F. Kohman, W. H. Eddy, and Celia Zall TEACHERSCOLLEGE. COLUMBIA UNIVERSITY, N E W Y O R K , N. Y.,A N D RESEARCH LABORATORY, NATIONAL CANNERS ASSOCIATION, WASHINGTON, D. C.
The vitamin A content of tomatoes is practically unTomatoes are subjected to OMATOES grown unaffected by the commercial processes to which tomatoes a number of commercial procder v a r y i n g condiand tomato products are commonly subjected. It is esses. These have not been tions-field-r i p e n e d , removed with the pulp by filtering. studied from the standpoint both raw and canned, greenThe vitamin B content of tomatoes is apparently of the vitamin content of the house tomatoes, green-picked somewhat affected by certain processes where excessive various resulting products. tomatoes for artificial ripenexposure to oxygen is not avoided. Filtering with Celite This is a report of such a ing, either spontaneously or lowered the vitamin B content, but it was not definitely study started in 1927 and with ethylene treatnientestablished that this was due to adsorption by the continued for three seasons. have been assayed for their Celite. Although subsequent to that vitamin content. Hess and Vitamin C in tomatoes is apparently quite stable to date, as noted above, there Unger ( 5 ) made extensive heat if oxidation is avoided. Concentration to twohave appeared data on greenexperiments with canned tofifths the volume by open-kettle boiling or to one-fifth picked tomatoes, the statematoes, using animals and the volume in vacuum requiring continuous, long ment of Clow, Stevenson, and human beings. As a result heating shows no evidence of vitamin C destruction. Marlatt (9)that canning inof their recommendation toAny preliminary process that introduces air, however, creases the vitamin C potency matoes have found wide usage will result in destruction of vitamin C in proportion of mature green-picked toas an antiscorbutic. Givens to this exposure and the temperature to which the matoes is of such significance and McCluggage (4) found product is subsequently heated. Data are given to that canned tomatoes after that data are included here show how steam may be employed to avoid contact on the following four lots: three years were practically with air in a manner which may have wide application (1) mature raw green tomathe equivalent of raw tomain the handling of foods. toes as an a n t i s c o r b u t i c . toes, (2) mature green toLaMer (7) found canned tomatoes canned, (3) mature matoes purchased locally to be the full equivalent in vitamin green-picked tomatoes allowed to ripen spontaneously, and C content of raw tomatoes grown in his own garden. Osborn (4) mature green-picked tomatoes allowed to ripen sponand Mendel (9) reported tomatoes as being rich in vitamin taneously and subsequently canned. B and even more potent in vitamin A (IO). I-Average Weight Increment a n d Survival Period of Groups Morgan and Smith (8) have reported that green-picked Table of Three Rats Receiving Amounts of Four Lots of Tomatoes T h a t tomatoes do not have their full vitamin A potency, but acProduce Comparable Results AMOUNT WEIGHT SURVIVAL quire it upon subsequent ripening, whether the ripening is CHANGE PERIOD REMARKS TOMATOES FED in light or dark, and with or without ethylene treatment. Days Mg. Grams House, Nelson, and Haber (6) studied the vitamin 4, 13, Larger and smaller amounts were fed also. green 1.50 +30 and C content of green, air-ripened, ethylene-ripened, and Raw On amounts here reCanned green 150 125 ported, there was aRaw ripened 7.5 +34 vine-ripened tomatoes. No difference was noted in the Canned ripened bout the same degree 75 +25 vitamin B content. Although green tomatoes do not conof A deficiency tain the full vitamin A potency of ripe tomatoes, all methods 11-Average Weight Increment a n d Survival Period of Groups of ripening produce the same effect. Green tomatoes like- Table of Three Rats Receiving Equal Quantities of Four Lots of Tomatoes wise do not have the vitamin C potency of vine-ripened .&MOl.INT \vEIGHT SURVIVAL REMARKS TOMATOES FED CHANGE PERIOD tomatoes, and although ripening them in air or with ethylene Grams Grams Days increases this, it does not make them equivalent to vineThe ripened tomatoes Raw green +31 5 ripened tomatoes. Clow, Stevenson, and Marlatt ( 2 ) state, Canned green kept the animals in +25 ? slightly better condiRaw ripened +42 however, that mature green-picked tomatoes may, upon Canned ripened tion +42 60 artificial ripening, become the equivalent of vine-ripened tomatoes in vitamin C, but that ripe greenhouse tomatoes Table "Average Weight I n c r e m e n t of Guinea Pigs Receiving Varying Amounts of Four Lots of Tomatoes are not the equivalent of field-ripened tomatoes in vitamin N O , OF AMOUNTWEIGHT SURVIVAL C. They further state that canning field-ripened tomatoes REMARKS FED GAIN PERIOD TOMATOES ANIMALS Grams Grams Days by the cold-pack method does not reduce their vitamin con5 5 217 90 Two animals had tent, while canning by the open kettle method exerts some Raw green scurvv 2 7 285 90 NO s c u r b destruction. Canned green 7 5 170 90 T w o animais had Delf (3) in England has reported considerable loss of vita. 3 7 230 90 No scurvy min C in the canning of tomatoes, the protective dose for a Raw ripened 3 5 270 90 No scurvy 3 280 90 Noscurvy guinea pig being raised from 2 cc. to 7.5 cc. The only com- Canned ripened mercial product she fed was in glass, and owing t o a limited Table I indicates that the vitamin A content of green supply she fed from these jars for a week or more after they were obviously fermented. Those she canned herself were tomatoes almost doubles upon ripening and that canning "heated gently for about ten minutes in a shallow pan" either the green or ripe tomatoes has little or no effect on before canning-a procedure one might expect to be par- their vitamin A content. Table I1 indicates that there is ticularly favorable to vitamin C destruction. no great difference in the vitamin B content of green and ripe tomatoes, raw or canned. Table I11 indicates that 7 1 Received June 16, 1930.
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I N D U S T R I A L A N D E,VGINEERING CHEMISTRY
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Curves Nos. 4, 6. 7, and S represent the same batch of tomatoes, and Nos. 9 and 10 a similar batch grown in the same locality. Nos. 11 and 12 represent tomatoes grown in another section of the country and in a different year. Nos. 4, 6, 7, 9, and 10 were fed on an equal solids basis as a solirce of vitamin A.
Chart 11-Various T o m a t o Products Fed t o R a t s as Sole Source of Vitamin B in A m o u n t s to Yield a b o u t S a m e Growth Increments See Chart I for source of various lots. No. 4 and No. 6 are on the same solids basis.
grams of green tomatoes, raw or canned, are about the equivalent in vitamin C of 5 grams of ripened green-picked tomatoes, raw or canned. Canned green tomatoes, according to Table 111, are not more potent in vitamin C than raw tomatoes, as stated by Clow, Stevenson, and Marlatt ( 2 ) . Their results may be plausibly explained by the fact that for feeding they grated their raw green tomatoes, a condition that according to Bezssonoff (1) permits of rapid oxidation of vitamin C. I n the manufacture of tomato products, such as tomato soup, tomato pulp, tomato paste, ketchup, tomato juice, etc., the tomatoes, either cold or after being preheated, are passed through a cyclone and finisher. The cyclone consists of a perforated sheet of metal in the form of a cylinder in which there are rapidly revolving baffles that force the pulp and juice through the perforations and extrude the skins, cores, and seeds from one end. The finisher is similarly constructed except that the perforations are smaller and the particles of pulp are thus more finely divided. This so-called cyclone juice is then concentrated for pulp or ketchup in large wooden tubs. The heat for concentration is supplied by high-pressure steam in large copper coils. Within 30 to 45 minutes the contents of a 500- or 1000-gallon tub are reduced to approximately two-fifths the original volume. For the production of paste, the concentration must be done in a vacuum pan to avoid scorching. P r o d u c t s Studied
To determine the effect of these various processes on vitamin content, the following products were studied: No. 7:Whole tomatoes, canned by the usual commercial proc-dure to serve as a control for the various other products. Solids content, 6.7 per cent. No. +The cyclone juice from similar tomatoes was allowed to flow into a vacuum pan, in which a high vacuum was maintained and was there heated to 140" F. A small portion was canned in No. 1 cans, processed 20 minutes in boiling water, and cooled. Solids content, 4.8 per cent. No. 5-The remainder of the cyclone juice was concentrated
Vol. 22, No. 9
under vacuum, during a period of 2l/2 hours, to the tomato pulp stage, and a small portion canned similar t o No. 4. Solids content, 13.2 per cent. N o . 6-The remainder of the pulp was concentrated under vacuum to the paste stage, requiring 2 hours additional, and canned similar to No. 4. Solids content, 23.0 per cent. No. &-&lite was added to a portion of the cyclone juice, which was then filtered free of the red insoluble pulp. This required l l / r hours. The clear filtrate was heated to 155' F. in buckets surrounded by hot water, filled into No. 1 cans, which after closing were cooked 10 minutes in boiling water and cooled. Solids content, 4.3 per cent. No. IO-A portion of another lot of cyclone juice was similarly heated to 155' F. in buckets and canned. Owing to lack of facilities a t the factory, the canning could not be done until 11/2 hours after the cyclone juice was made. Solids content, 5.1 per cent. No. 8 and No. 10 are thus on a fairly comparable basis from the standpoint of time elapsing before canning No. 9-Cyclone juice represented in No. 10 was evaporated to pulp in the usual way in an open wooden tub with copper coil to a solids content of 13.4 per cent. This required 45 minutes. Before the evaporation could be started 25 minutes elapsed, and before the finished pulp could be canned 20 minutes more elapsed. Although these delays are met with in practice, they are not normal.
Tomato juice has of late come into vogue for various beverage purposes. No standardized procedure has yet been worked out for its production. Therefore in 1929 the following two tomato juices were canned and studied for their vitamin content.
No. 11-While peeled tomatoes are accumulated in buckets and after they are dumped onto grated filling tables, a considerable amount of juice exudes from them. This juice is generally discarded. It comes largely from the seed pockets, contains less sugar and insoluble solids, but more acid and mineral salts than cyclone juice. It was believed that oxidation would not have the same destructive effect in this as in the cyclone juice, No. 10, since it is not subjected to violent agitation in air. The cold juice was filled into cans which were passed through a steam exhaust box, closed, processed for 10 minutes, and cooled. Solids content, 4.2 per cent; insoluble solids, 0.17 per cent. No. 12-Cyclone juice for pulp is frequently made by first preheating the tomatoes to the boiling point with live steam. This dilutes the tomatoes with 10 per cent or more of water. It results in a finer division of the pulp particles, which would be advantageous in keeping the pulp in suspension in tomato juice. The manner of preheating would not tend to introduce air and thereafter it was believed the water vapors of the hot product would afford protection against air. The hot cyclone juice was filled into cans, which were then closed, processed for 10 minutes, and cooled. Since such a product is not generally canned, the lack of equipment made it necessary to fill by hand. This caused a delay of 30 minutes. This adverse condition would be eliminated in a continuous commercial process. Solids content, 5.4 per cent; insoluble solids, 0.73 per cent. Experimental Procedure
All of these products, as well as other similar ones not here recorded, were fed to rats and guinea pigs to determine their potency in vitamins A, B, and C. Each product was fed in a t least three varying amounts for each vitamin, and as a rule to three animals for each dosage. It would have been desirable to have all the products from one lot of tomatoes to make the various operations to which they were subjected more directly comparable. This was physically impossible. As it was, delays were unavoidably introduced that in an established commercial process would be eliminated. Nevertheless certain conclusions are evident from an examination of Charts I, 11, and 111.
September, 1930
INDUSTRIAL A N D EXGINEERING CHEMISTRY biscussion of Results
1017
Lot No. 11 is of interest in showing that when the tomato juice is obtained in a quiet way that would avoid beating air into it, there is less destruction of vitamin C than in cyclone juice. (Compare No. I1 with No. 10.) No. 12 is of interest in showing that damaging air is evidently not beaten into the juice during cycloning while it is hot. d p parently the atmosphere of steam affords a protecting en-
From Chart I and additional data that are omitted for lack of space, it appears that, if the various products are fed on equivalent solid levels, their vitamin A potency is approximately similar, with one exception; KO.8, which was filtered, has lost most of its vitamin A. Sirice S o . 7 contains the core a n d seeds that t h e o t h e r s lack, it is not exactly comparable. Concentrat i o n of N o . 4 u n d e r vacuum to about one-fifth of its volume gives a product (No. 6) approximately five times as potent in vitamin A. Also concentration of No. 9 to a b o u t two-fifths of its volume in an open kettle yields a product (No. lo) correspondingly potent in vitamin A. Chart I1 is equally instructive. No. 6, condensed about 5 to 1, is approximately five times as potent in the combined B vitamins as No. 4. KO.8, which has been filtered has, however, lost about two-thirds of its Chart 111-Growth Curves of Guinea Pigs Receiving Various T o m a t o Products as a Source of Vitamin C vitamin B. This is inSee Chart I for source of the various lots. teresting in view of the water-soluble nature of‘ vitamin B. It is possible that the velope. If this explanation is accurate, this principle should Celite used may have had some adsorptive power for vitamin be of considerable importance as it should find application B. It is further interesting t o note that No. 10, which is in many processes in the canning and cooking of foods. By No. 9 before being concentrated to about two-fifths of its performing any operation on food products in steam, grindvolume in an open kettle, is only about one-fourth as potent ing, grating, crushing, etc., could be accomplished without in vitamin B. The loss in No. 10 may be due t o oxidation contact with air. I n the present state of our information before and during canning. This will be discussed in Chart as to the effect of various processes on vitamins, this should I11 in connection with vitamin C, where the effect is more not be assumed to be a cure-all, but needs in each instance to be checked by actual tests. pronounced. Several striking facts are indicated in Chart 111. I n no Literature Cited product studied was the vitamin C conserved as in the regularly canned whole tomatoes. Although concentrated prod(i) Bezssonoff, Compt. vend., 172, 92 (1921); Bull. soc. hyg. aliment, 8, ucts such as No. 5, No. 6, and S o . 9 were somewhat more 622 (1921). (2) Clow, Stevenson, and Marlatt, J . A i r . Research, 40, 767 (1930). potent per volume in vitamin C than the canned whole (3) Delf, Biochem. J., 18, 674 (1924). tomatoes, considerable vitamin C loss occurred. This was (4) Givens and McCluggage, Proc. SOL.E r p l l . Bid. M e d . , 18, 164 (1921). apparently not the result of concentration. It appears to ( 5 ) Hess and Unger, I b i d . , 16, 1 (1918); Am. J . Diseases Children, 17, 2 2 1 be in the production of the cyclone juice, since a compari(1919). (6) House, Nelson, and Haher, J . B i d . Chem., 81, 495 (1929). son of No. 4, KO.5 , and No. 6 indicates vitamin C potency (7) LaMer, Dissertation, Columbia University, 1921. of the same order as the concentration. (8) Morgan and Smith, Proc. SOC.E w p t l . B i d . M e d . , 26, 44 (1928). Particular attention is called to the almost complete loss (9) Osborn and Mendel, J . Bid. Chem., 41, 461 (1920). of vitamin C in S o . 10. This we ascribe to the air that is (10) Osborn and Mendel, I b i d . , 41, 549 (1921). beaten into the cyclone juice by the baffles. This air is in the form of tiny bubbles which are entrapped by the pulp, The Government’s Helium Plant, near Amarillo, Tex., deas evidenced by the fact that the pulp rises to the top. A of vacuum corrects this so that the cyclone juice may be canned signed, built, and operated by the United States Bureauyear Mines, produced 9,801,060 cubic feet of helium in the and about half the vitamin C conserved (No. 4), or it may ended June 30, 1930. This was the first fiscal year of operation. be first concentrated to varying degree and then canned Although the plant operated only ten months of the fiscal year, with no appreciable further loss ( S o . 5 and No. 6). Filter- having been closed in December, 1929, and February, 1930, for ing this juice makes it possible to can it with even less loss lack of orders, the production was the largest ever turned out by Government in one fiscal year, being about 800,000 cubic of vitamin C after canning ( S o . 8)--evidence that the damag- the feet greater than the largest fiscal year’s production of the Goving air is entrapped in the pulp. Or again, rapidly heating ernment’s Fort Worth Helium Plant, which formerly supplied this cyclone juice to boiling and concentrating to two-fifths helium used by the Army and Navy. Even with this proaction the plant was operated at only a of its volume in an open kettle by boiling for 45 minutes fraction of its present capacity-24,000,000 cubic feet per year. does not permit the entrapped air to exert a destruction Its output is limited by the demand of the Army and Navy of half the vitamin C (No. 9). rather than by its capacity to produce.
