July 1949
INDUSTRIAL AND ENGINEERING CHEMISTRY
large amounts of dissolved qxygen were present. So far as could be determined, the samples were free from toxic substances which might retard the rate of attack on the phenolic materials being investigated. It would be unwarranted to use the material presented to estimate the rate of dissimilation of phenol in acid streams, such as are encountered in the upper Ohio River Basin, under conditions of septicity or very low oxygen tension, or in the presence of toxic materials. Although the samples studied have not included waters that introduced these factors, they do occur and may be of critical importance under such circumstances.
I
I
I
I
1427 I
I
I
SUMMARY AND CONCLUSIONS
Microbiological action is the principal cause of the removal of phenol and the cresols in surface waters. Rates of removal of these materials are governed by the factors that control the metabolism of the microbiological agencies involved: the temperature, the characteristics of the microflora and fauna present, ,microbiological lags, the specific compound involved, the amount of the phenolic material involved, and the presence of the auxiliary nutrients in the substrate which make possible the metabolism of the phenolic material by the active agents. I n any individual sample, the exact course which the removal of the phenolic compound will follow cannot be accurately predicted. A chart is presented for the guidance of those required to estimate the low temperature persistence of such compounds in waters of different types. ACKNOWLEDGMENT
The authors wish to acknowledge the assistance obtained from Hayse Black, sanitary engineer, in obtaining the samples from the Detroit area. Stephen Megregian, sanitarian, carried on some of the early persistence experiments, and Ray Lishka,
Figure 4. Conservative Estimate of Persistence of Phenol (1000 P.P.B.) i n River Waters of Different Types at 4' C. under Aerobic Conditions 1.
Water having a history of recent recovery from phenolic pollution (B.O.D. d u e to sewage over 3 p.p.m.) 2. Sewage-polluted water, B.O.D. over 3 p.p.m. 3. Relatively pure water, B.O.D. under 1 p.p.m.
scientific aide, assisted in the analysis of the residual phenolic compounds in many of the euperiments. LITERATURE CITED
(1) Congress (78th), 1st Session, House Document 266, Vol. 2, p. 519 (2)
(Report of Ohio River Committee). Ettinger, M. B , and Ruchhofr, C. C., AVAL.CHEM, 20,
1191
(1948). (3) Ettinger, M. B., Schott, Stuart, and Ruchhoft, C. C , J . Am. W a t e r Works Assoc., 35,299 (1943). (4) Harlow, I. F., Powers, T. J., and Ehlers, R. B., Sewage Wonks J . ,
10, 1043-59 (1938). (5) Ruchhoft, C. C., and Ettinger, M. B , Third Industrial Waste
Conference, Purdue University,
321-50 (1947).
( 6 ) Stieeter, H. W., Pub. Health Rept., 44,2149 (1929) ; Reprint 1313. RECEIVED J u n e 30, 1948.
Chemical Decomposition of Cane Siru and Molasses during Storage R. E. HENRY AND L. E. CLIFCORN Continental Can Compuny, Chicago, I l l .
T h i s investigation was undertaken in an attempt to provide a remedy for the problem of the occasional occurrence of swells i n cans of cane sirup and molasses. Accordingly, a processing procedure was developed involving the use of resinous ion exchangers which materially extended the shelf life of the cane sirup in some instances. During the course of the work, the decarboxylation of aconitic acid in the presence of calcium and magnesium salts was shown to be a source of the carbon dioxide formed during storage of the product.
F
OR many years the sirup canning industry has been confronted with the problem of the occurrence of swells in cans of cane sirup and molasses owing to the liberation of carbon dioxide during storage. This has been a very perplexing problem to the sirup canner and has resulted in severe financial losses. The investigation was undertaken with the view of providing a remedy for this problem without necessarily unraveling the mechanism of the reactions responsible for the carbon dioxide liberation from such a complex material as cane sirup.
The essence of the information available in the literature may be summed up in the following four points: 1. The carbon dioxide is produced as a result of the spontaneous decomposition of unstable organic material? rather than, the action of microorganisms. 2. The amino acid-reducing sugar reaction (Maillard reaction) may or may not be a major contributor t o the production of carbon dioxide. The evidence is somewhat in favor of the reaction playing only a minor role. 3. The glucic acid theory or production of unsaturated easily oxidized materials from overliming of cane juice may be of significance, but seems to be lacking in supporting evidence, especially in the case of cane sirup which is not customarily treated with lime or alkaline materials. 4. A third and less definite proposal-that of the catalytic effect of the mineral constituents on the unstable organic materials of cane sirup-seemed more plausible and served as a guide in the investigation.
(a,3, 5, 7 ) a t the beginning of the investigation
INDUSTRIAL AND ENGINEERING CHEMISTRY
1428
TABLE I. STUDYOF IKFLUESCE O F CATION EXCHANGER ON CAXESIRL-P Treatmenta 2 3 4 5 4.6 3.38 2.9 1.86 PH 5.1 5.1 -4djusted.p.H 5.1 5 8 : 23 Ash alkalinityb 7.58 4.12 5,ei 3.09 Alkalinity reduction, yo 31.8 8.0 50.1 73.4 Bsh. % 2: 52 2.14 1.64 1.25 0,973 Aih'rehovai, % 35 15 61.4 50.4 9: b 13 8 Pressure lb./sq. in. 2.14 2.24 2 9G Pressure'reduction, 7a 28.4 .. 67 74 69 1, stock sirup with refractive index of 1.478; 2 , 4 grams of cation eschange mat,erial per 100 grams o i sirup; 3, 16 grams of cation exchange material per 100 grams of sirup; 4, 32 grams of cation exchange material per 100 grams of sirup: 5 , 64 grams of cation exchange material per 100 grams of sirup. b Expressed in niillieguivalents of EIC1 per gram of ash. 1 5.1
EXPERI3IEZTA L
,
At the beginning of the study it was apparent that it lvould be desirable to have an accelerated aging t'est in order to avoid the prolonged storage of the variously t,reated samples, inasmuch as the gas is produced slowly from cane sirup a t room temperature or the customary incubation temperature of 37" C. Accordingly, a 100-ml. sample was placed in a 4-ounce crown-capped bottle, with a 25-cc. headspace. The sample was heated for 2 hours a t 110' C. and the pressure developed was measured by piercing the crown cap with a piercing mechanism attached to a pressure gage, n-hich registered the pressure in pounds per square inch. This was later modified by attaching to the piercing device an open end manometer having a mercury leveling bulb which permitted the gas pressure t o be measured more accurately and to be reported in millimeters of pressure or cubic centimeters of carbon dioxide a t standard temperature and pressure. 9 Louisiana cane sirup known to produce carbon dioxide during storage was selected as a starting material for the study of the catalytic influence of various cat8ionson t,he spontaneous production of the carbon dioxide. I n considering a means of altering the mineral content of the cane sirup and still retaining a product having the original sirup characterist,ics it n-as noted that EngIis and Fiess (4) had lowered the ash content of an extract of Jerusaleni artichokes by the use of a synthetic cation exchanger operat,ing on the hydrogen cycle. I n addit'ion, the p H was adjusted or the acidic constituents removed by passage through a bed of a synthetic anion exchanger. By way of further description, a synthetic cation exchanger operating on a hydrogen cycle has the property of replacing all the mineral constituents of an aqueous solution with hydrogen ions. Thus, if a solut,ion of sodium chloride, or any other soluble chloride is passed through a bed of the cation exchanger the cation Rill be removed quantitat'ively and rcplaced with hydrogen ions giving a hydrochloric acid solution. This action may be illustrated by the following equation:
+
HR (Cation exchanger)
SaClc-IiaR
+
HCI
If, t,hen, the resulting hydrochloric acid solution is pasaed through a bed of the synthetic anion exchange resin, which absorbs the acid constituents, the whole hydrochloric acid molecule will be taken out quantitat,ively,permitting only the water t o remain. The action is shown in the following equation: RX
+
(Anion exchanger)
HC1
~2
RX: HC1
(Resin hydrochloric acid complex)
A number of these synthetic ion exchange materials are now commercially available and hax-e been improved considerably over the past few years. The stock of 1,ouisiana cane sirup referred to preriously TTas found to develop 4.2 pounds of pressure when heated 2 hours a t 110' C. The diluted stock sirup was passed through a cation exchanger, then through an anion exchanger, and the p H n-as adjusted to the original of 5 to 5.2 with hydrochloric acid. T h e recovered sirup after reconcentration under vacuum t o its original solids gave when heated only 0.17 pound of pressure. Although this gave a sirup having very little of the characteristic flavor remaining, i t was the first experinlent t,o provide a very decided reduction of the gassing properties of cane sirup. I n accordance with this it was decided to study the influence of the cation exchanger alone and determine whether there was a relationship between ash removal and the gas-producing properties of cane sirup. In this series of experiments varying amounts of the cation exchanger were added batchwise to each of several 100-gram samples
Vol. 41, No. 7
of cane sirup, the viscosity of which had been reduced by diluting with twice its volume of distilled water. After allowing t,he ion exchange material t,o remain in contact n4t.h the diluted sirup for a short time t8heresin was filtered off, an aliquot taken for ash det,ermination, the filtrate adjusted t o the original pH with sodium hydroxide, concentrat,ed under vacuum to its original refractive index, and pressure tested by heating 2 hours a t 110" C. This procedure provided the data presented in Table 1. Table Ishows that there is a definite lowering of the pressure developed in the accelerated test and t,hat a t the same time t,here is a reduction in t'he ash content. Since the cation exchanger supposedly removed only t,he cationic material, there is a good indication that those cations being removed are in some manner involved in t,he production of carbon dioxide, probably catalytically, as the source of the carbon dioxide is organic in nature. At this point a question m-as brought up as to whether tJhe accelerated aging test was giving a reliable measure of t8hebehavior of cane sirup on storage. To test, this a large batch of diluted cane sirup was treated first with the cation exchanger, and then with the anion exchanger, &til the pH had been returned from t.he low p H of the cation exchanger treatment t,o approximately the original pH. The accelerated gas evolut,ion test gave 13 pounds of pressure for the untreated sirup and only 2 pounds of pressure for the t'reated sirup. The treated and uiitreated sirups were packed in S o . 2 cans and stored a t 98" F. until the cans swelled owing to the production of carbon dioxide. The data obtained from this storage test showed an actual 100% improvement in shelf life as against the 160% improvement predicted by the accelerated test. Although the accelerated test did not predict the per cent improvement quantitatively, it seemed satisfactory from the qualitative point of view. The importance of returning the test samples to the original p H or t,he p H of the control samples is iliustrated by the following data:
0
Stock sirup Stock sirup Stook sirup Normal pH.
p H 4 . 2 6 Heated 3 hr. a t 110' C. Heated 3 hr. a t l l O o C . p H 34 p H 6 , 0 5 Heated 3 hr. ao 110' C.
13.5 lb./sg. inch 10.3 Ib./sq. inch 3 . 0 lb./sq. inch
This increase of pressure Jvith increase of acidity has been noted by other investigators and the above data merely substantiate their findings. Samples from the stored untreated and treated cane sirup described above were submitted for chemical anallsis, JI hich gave the data in Table 11. The data in Table I1 served as a basis for the amounts of cations added to cane sirup which had been decationized by treatment with the cation exchanger. The p H of approximately 2 for the treated sirup was adjusted to the nornial p H of 5 with potassium hydroxide, the cations were added stepwise, and the sirup pressure was tested. From this series of experinients the data in Table I11were obtained. From results in Table 111 i t seems fairly obvious that the calcium ion is a definite contributor to the decompofiitioii of cane sirup.
TABLE
11. RESULTSO F
C H E M I C A L AkSAI,Y81S O S
STORED
USTREATEDASD TREATED CANESIRVB
Constituents
Aluminum Copper Sulfur trioxide Potassium Sodium
Untreated,
Tieatcd,
0.051 0.078 2.49 0.0024 0,023 0.145 0.024 0.270 0.0468 0,0014 0.00032 0.2161 0.98 0,027
0.040 0.048 1.12 0.001 0.0066
70
%
0 0345 0.016
0.186 0.0169
0,001 0.00018 0.0911 0.40 0.078
INDUSTRIAL AND ENGINEERING CHEMISTRY
July 1949
ml. of gas a t standard temperature and pressure. I n all the runs except No. 1, where neither calcium nor magnesium was added, a voluminous flocculent precipitate formed during the heating cycle. As a consequence it was impossible to know the quantities of active ions remaining in solution. I n general, however, it appeared that increasing the amounts of magnesium increased the amount of carbon dioxide produced within the limits examined. On the other hand, calcium seemed to have a slightly stimulating effect by itself, but i t tended t o reduce or inhibit the stimulating effect of magnesium, while in the absence of aconitic acid no gas was produced.
TABLE111. SIRUP PRESSURE Treated Sirup Control treated b u t no addition of minerals Treated cane sirup FeCh Treated cane sirup FeCh MnSOd Treated cane sirup FeCh MnSOa CaClz Treated cane sirup FeCla i\fnSOd CaClz
+ + + +
+ + +
TABLE Iv. RESULTSO F
+ +
PRESSURE
Lb.'Sq. Inoh
4- AIgClz
TESTO N
Conditions
1
Control (containing 1%aconitic acid) Control phosphate buffer 2 CaClz i\IgCh 3 R'IgClz
+ +
SYXTHETIC
2 4 6
3
1
SIRUP
Pressure, Lh./Sq. Inch
Sample 2 3 4
3 3 3 12 10
From the complexity of cane juice and cane sirup it does not seem that the aconitic acid should be the sole source of carbon dioxide. If this were true the gassing property of a cane sirup would be reduced as aconitic acid mas destroyed or converted t o itaconic acid, which does not produce carbon dioxide under the same conditions. With this in mind, it mas decided to heat cane sirup for 2-hour periods a t 110" C., measuring the gas produced a t each heating interval, and continue heating until the production of gas had ceased. For this purpose 100 ml. of cane sirup were placed in each of three 4-ounce cro.ir.n-capped bottles and heated for 20 periods, giving a total of 40 hours of heating a t 110" C. Although the trend was toward a less amount of gas a t each heating, gas was still being given off and there had been accumulated 465 ml. of carbon dioxide from 100 ml. of sirup. The total volume of gas produced in this heating exceeds by approximately three times that amount which would be produced by 1% of aconitic acid if it were completely converted t o earbon dioxide and itaconic acid. This is a strong indication that other reactions are taking place which also produce carbon dioxide and although aconitic acid may be a major contributor to the production of carbon dioxide it is very likely notthe only source. Returning to the development of a of improving the shelf life of sirup, it was decided to obtain TaW cane juice directly from a Louisiana sirup mill and try various combinations of cation and anion exchanger treatments with it to determine the best cycle to llse from the standpoint of both flavor and shelflife improvement. The raw cane juice so obtained, preserved with chloroform, was from the last of the grinding season and consequently was rather inferior in WalitY-haviW a PH of 4.5 uThich was a little below normal. However, the p H was adjusted to 5 with calcium hydroxide and treated according to the following schedule:
0.9
++
1.5 14.5 15.6
Although the above findings show a decided catalytic effect of the calcium ion, very little information is available as to the source of the carbon dioxide formed during the decomposition. One might assume, however,that one source of carbon dioxide is the carboxyl group of some unstable organic acid. Inasmuch as it has been shown by McCalip and Seibert ( 6 ) and later supplemented by Balch, Broeg, and Ambler ( 1 ) that aconitic acid has been found in cane sirup in amounts of 0.75 to 1.33% with very little other organic acids present, i t was decided t o determine the effect of the minerals on the decomposition of this acid. Synthetic sirup was prepared with 30% invert sugar and 30% sucrose, to which was added 1%of aconitic acid and the p H was adjusted to 5 by the addition of phosphate buffer. Samples of this synthetic mixture were pressure tested by heating 2 hours a t 110' C. The results of these experiments are found in Table IV. The results show a definite influence of the cations calcium and magnesium on the decomposition of aconitic acid a t a p H well within the range of normal cane sirup. Following this initial experiment a more elaborate series of experiments was made to determine the effect of various amounts Of Calcium and magnesium ions on the gasification of a synthetic sirup containing constant amounts of aconitic acid and phosphate. From these experiments the data in Table V were obtained.
These samples were heated at l l o o C. for hours in crown-capped 4-ounce bottles with an approximate 25-cc. headspace, and the volume of carbon dioxide produced was reported as
"I
Val
CC Run Sucrose, S o . G./100 1
60
Aconitic Acid, G./100 G. 1
Ca +, M g + + G./100 G./lO6 +
0.00
0.00
Phosphrtte,
G./100
60
1
0.02
0.00
0.75
3
GO
L
0.04
0.00
0.75
4
60
1
0.06
0.00
0.75
5
60
1
0.00
0.145
0.75
6
GO
1
0 02
0.145
0.75
7
GO
1
0.04
0.145
0.75
8
60
1
0.06
0.145
0.75
9
60
1
0.00
0.03
0.75
10
60
1
0.00
0.06
0.75
11
60
1
0.00
0.12
0.75
12
60
1
0.00
0.18
0.75
13
60
1
0.05
0.03
0 75
14
GO
1
0.05
0.06
0,75
15
60
1
0.05
0.12
0.75
16
60
1
0.05
0.18
0.75
GO
0
0.05
0.18
-
-.
0.75
1
2 1 2 1 2 1 2 1
2 1 2 1 2 1
2 1
2 1 2 1
2
1
2 1 2
I
1.27 1.11 1.40 1.51 1.94 1.81 1.43 1.43 4.17 4.55 5.25 3.91 5.38 4.44 2.86 2.26 1.17 0.93 2.57 2.95 4.28 5.90 6.27 7.90 1.17 1.27 1.40 1.17 1.91 2.05 4.55 5.09 0 0
1. Control, no treatment, merely concentration
.
>.".
0.75
2
17
1429
6.25
5.18
5.15 5.05 4.90 4 95 5.00 5.00 4.60 4.55 4.55 4.60 4.40 4.40 5.00 5.00 4.95 4 95 4.75 4.75 4.45 4.55 4.35 4 35 4.55 4.66 4 60 4.60 4.45 4 60 I
4.60 4.70 4.27 4.35
Comments Soln. clear Yellow color Flocculent ppt. Yellow color Flocculent ppt. Yellow color Flocculent ppt. Yellow color Flocculent ppt. Yellow color Flocculent ppt. Yellow color Flocculent ppt. Yellow color Flocculent ppt. Yellow color Flocculent ppt. Yellow color Flocculent ppt. Yellow color Flocculent ppt. Yellow color Flocculent ppt. Yellow color Flocculent p p t . Yellow color Flocculent ppt. Yellow color Flocculent ppt. Yellow color Flocculent ppt. Yellow color Flocculent ppt. Yellow color Flocculent ppt. Yellow color Flocculent ppt. Yellow color Flocculent p p t . Yellow color Flocculent ppt. Yellow color Flooculc-' --I Ti^>> -... c u b UPb, I(ill"W U"I"1 ent, n n t YPllnur, rnlnr Floccul.___ Flocculent ppt. Yellow color Flocculent ppt. Yellow color Flocculent ppt. Yellow c o l o ~ Flocculent ppt. Yellow color Flocculent ppt. Yellow color Flocculent ppt. Ye!!ow color Flocculent ppt. Y eliow color Flocculent out. Yellow color Flocoul ent Gt. Yellow color Floccul ent ppt. Yellow color Floccul ent ppt. Yellow color
____ _____ ____ ..1.-
~
Treated k t h the cation e x c h a n g e r , p H adjusted with potassium hydroxide Treated with the cation e x c h a n g e r , p H adiusted with calcium hydroxide Treated with the cation exchanger, then anion exchanger t o give p H 5 Treated with anion exchanger t o give p H 6.54 t h e n a d j u s t e d wit,h juice from the cation- exchanger to p H 5.0. This riquired 215 ml. per liter of the higher p H juice. After concentration these samples were s u b j e c t e d t o the gas evolution test which gave the data in Table VI.
INDUSTRIAL AND ENGINEERING CHEMISTRY
1430
Vol. 41, No. 7
CONCLUSIOh OF G.L~EIOLUTIOX TEST TABLE VI. RESULTS
Treatinent KO. 1 2 3 4 5
Time and Temp. 2 hr. a t 110" F. 2 hr. at 110' F. 2 hr. a t 110' F. 2 hr. a t 110' F. 2 hr. a t 110' F.
Pressure, L b.1d q . Inch 10.5 0,G 4.5
0.0 0 .1
PH
Reinnrlis
after Heat
Sediment formed Sirup clear Sirup turbid Sirup clear Sirup slightly fogg2;
4.76 4.91 5.03 4.13
5.43
Flavor tests of the samples prepared from t,lie various treatments of Table V I were made by several members of the laboratory and the general consensus was that treatment 5 provided a sample that was satisfactory, being even superior to the control and only slightly different from thc commercial grade of cane sirup. This difference was apparently due to a slight loss of the characteristic strong flavor of Louisiana cane sirup. The sample from treatment 4, however, had lost most of its flavor, being bland in character, but rather pleasant,. This may be desirable from t,he point of view of those consumers who dislike strong flavors, but it no longer resembles that of the original product. From the standpoint of flavor and shelf-life improvement i t seemed fairly obvious that treatment 5 should be the best cycle t o emplo?. The ran- cane juice after sedimentation and filtration is first percolated t,hrough the synthetic anion exchanger. This percolation which removes thc acidic constituents caused the pH of the cane juice to be increased from its normal 5 to 5 . 2 t o approsiniately 6.5. I n order to reduce rhe p H to its normal value without the addition of foreign acid, a portion of this treated cane juice is passed through a synthetic cation exchanger on the hydrogen c>-cle, which reduces the pH to approximately 2 . This juice is then blended with anion exchanged juice having a p H of 6 . 5 until the normal pH of 5 to 5.2 is obtained. This blending procedure usually requires 1 part of the Ion-pH juice t o 4 parts of the juice having the higher pH. The cane juice is then boiled don-n in an open kettle to a sirup of the desired Brix. Because insufficient cane juice had been obtained t,o inalre an!test packs of the treated sirup, it was decided to obtain larger quantities during the nest grinding season, in order to obtain more reliable information on the behavior of the treated cane sirup on prolonged storage. For this purpose a 25-gallon batch of ran' cane juice was obtained from each of three sirup mills in the Louisiana district. Each batch M-as divided into two portions, and one portion treated in accordance n-ith the previously described procedure, while the other was merely boiled down t,o t,he correct Brix. These sirups were then packed in E o . 2 cam and incubated at 98 E'. until the cans svelled. From this storage test the folloiying data were obtained: Sirup
A
R
C
Pi edicted Shelf-Life Improx eluent, 0 100 140
rc
.Lctual Shelf-Life Improveinenr
5;
0 100
75
Accoiding to these data the accelerated aging test gave the prediction of no benefit from the treatment for one out of the three sirups. This was substantiated by the storage tests. The apparent discrepancy was disturbing, as none of the previous work had indicated that anything like this would occur. So disturbing was this finding that samples of cane sirup packed during this season were obtained from siiup mill ii and put through the same procedure. The accelerated piessure tests again predicted that no benefit could be accomplished by the use of the ion exchangers for this particular cane juice. From the over-all point of view i t seems that more than one characteristic reaction is responsible for the gaseous decomposition and only one type is being reduced by the ion exchange treatment under those conditions described. I t is apparent that the raw product is variable and in order to apply this method it would be necessary first to tkst on a small scale over a period of time raw juice from that particular geographical location to determine its response.
In connection with the possible use of this procedure for the shelf-life improvement of canned cane sirup, or for the treatment of sugar cane juices in general, the possibility of the recovery of a valuable by-product, aconitic acid, or its salt is of particular interest. During the course of this investigation it was shown the aconitic acid was quantitatively removed from a synthetic sirup medium by the anion exchange resin and approsiniately 6070 of the absorbed acid v a s recovered from t,he regeneration effluent. It was also shown qualitatively t"nat the aconitati: ion v-as present iii the regeneration effluent of the anion exchanger used in treating the diluted cane sirup. This evidence is offered in support of the possibility of the recovery of aconitic acid which according to current interest in the acid might provide R reasonable economic return t o the cane sirup manufactuier as well as other benefits such as t'he improvement in flavor and shelf life o f the canned product. Furthermore, as Balch, Broeg, and Inibler ( 1 ) have stat,ed in their article on aconitic acid in sugar products a method such as described wherein the acid could be reinoved from cane juice prior to evaporation and crystallixatior. of sugar ~ o u l dbe an improvement over their present method of separating aconitic acid as the precipitated calcium salt from niolasses. Although the practical application of this procedure did not function entirely as the preliminary work indicated it might, there are a iiuiiiber ot findings which have a significant bearing on the perplesing phenomenon of gas liberation. The lLIaillarc? renction, evcn at the present time, is still believed by several t o be the explanation for the chemical decomposition, but in this investigation no evidence was found to support it. It was observed' in one instance that a change in pH t'oward the acid side. greatly increascs the decomposition rabe as measured by the production of gas in comparison to the rate a t the higher pH of 6.5. This is certainly not in accord with the typical Maillarc', iwction where the rate is greatly enhanced by shifting t,he pH toward the alkaline side. I n addition, as was shown, t,he reduction in protein nitrogen was rather insignificant in compariwIi t o the reduction in the tendency to produce gas. These observations can hardly be interpreted to support t'he amino acid-reducing sugar reaction, but rat,her point: toward some othw reaction as the source of carhon dioxide. The evidence is not sufficient, however, to eliiiiina.te the Maillard reaction entirely, but definite enough, the authors believe, to relegate thc rcactiori t o a very minor role. The major role appears to be played by the ash constituents of the cane juice especially the n1li;aline earths calcium and magnesium. The catalytic influence of these inaterials upon aconitic acid has been fairly well demonstrated and as t,his acid has been found in the ra,w product, i t does not seem too far afield t'o assume that aconit,ic acid may be i: significant source of carbon dioxide. ACKNOWLEDGXIENT
The authors n+h to express their appreciat'ion of the assistance given by C. 11. Breden, J. Dahl: arid William Winokur during the course of this investigation. LITERATURE CITED (1) Baich, R.T., Brocg, C. B., and Ambler, J. A,, Sugur, 40, 32 (1945). ( 2 ) Browne, C. A . , Chem. Eng. IVeu's, 17, 734 (1940). ( 3 ) Browne, li., I N D . ENG.C H E M . . 21, 600 (1929). (4) Englis, D. T., and Fieus, H. A , , I b i d . , 34,864 (1942).
KO,10,
c.
( 5 ) Lafar, Franz, Oesterr. ungar. 2. Zzickerind. u. Landqw.. 42, '737 (1913).
( 6 ) McCalip, bI. A, and Seibert, A.
(7)
H., 1x11.ESG. CHICM..33, 637
(1941). M a i l l a r d , L. C., Compt. rend., 153, 1078 (1911).
R E C E IETD 31av 1 , 1948.
