Soveniber. 1929
114.5
I S D c-STRI.4 L, d S D E S G I S E E R I S G C H E V I S T R Y
The production of acids, as evidenced by decrcase in p H (Figure ll), is well marked at 9 i " C., but less so a t the other temperatures. It is irregular in many cases, owiiig probably to the lack of buffer salts. Another way of showing t'he strikingly different behaviur of invert sirup is to plot the increase in color (instead of t'lie actual color values) for the total time of heating against the initial pH. Such curves for sorghum have aheady been presented in the lower of each pair in Figure 7. Those for the others are given in Figure 12. The amount of total color production in sorghum and glucose is independent of the pH, but in invert sirup it increases w r y ra.pidly with increase in pH. The above differwces must be due to the fructose content of t'he invert sirup. Allowing for t,he amount of inversioii in both cases, the diluted invert sirup contained 6.9 per cent fructose and the sorghum 2.25 per cent. This greater des h c t i b i l i t y of fructose over glucose and sucrose is in accord with our general kno~vledgeof these sugars. It is obvious that marked inversion in sorghum juice is likely to he the cause of color development in the sirup-inaking process. Conclusions
for predicting the increase in color of sorghum juice clue to concentration alone, and by means of it color forniatioii during the process of evaporation may be detected. 4-The pigment,s of sorghum juice do not change color from acid to alkaline, but they change in intensity linearl~. d h the pH. 5-When diluted sorghum sirup is heated a t various pII'*. color and acids are produced. The amount of color is proportional to the temperature, hut is independent of the initial pH. This is largely due to the decrease in pH with i t > concomitant decrease in color intensity. 6-When glucose solubions are heated in t>hesaii~ci i i m i i ( ~ there is some increase in color and a decrease in pI-1. As iii sorghum, the color formation is proportional to the tmiper:iture and independent of the iiiit,ial pH. i-Invert sirup behaves quite differently, owing tu tlic, fructose. There is a very great increase in color, and thih increase is greater the greater the pH. Probably most colnr production in sorphnin sirup is due to tlie fructose present. 8-111 factory practice the most important factors in color production are the degree of inversion of the siicrow and the length of time and the temperature a t which the juiw is held, assuniing that, the reaction nevcr lwcoinc~salkalinc~.
1-The l'fund color grader is a highly satisfactory instriiinent for evaluat,ing the color of sorghuni sirup. The colored glass wedge of one of these instruments has been calibrated (1) against a spectrophotometer. d reference table of t'his ( 2 ) calibration is given here. 13) ) 2-The Bailey hydrogen electrode is very satisfactory and ) dependable for measuring the pH of sorghum juice up to a density of about 55" Brix. (G) 3-Five samples of sorghum sirup showed a s~raight~-line ( i j relation between log of concentration (in degrees Brix) 14) and color value. .I reference table has been constructed (9)
Literature Cited Andersoti, J. I N D . I ~ N GCHGM., . 9, 492 (1917) hlathews, 3. Biol. Chrm., 6, 3 (1909). h-ef, A n n . . 403, 204 (1913). Paine and Balch, Facis .Ihoul S u g a r , 22, 338, 362, 336 ( 1 9 2 i ) . \villaman, Sugar, 24, 83 (1922); Chem. Me/ Enq.. 31, 314 Food I n d u s / v i e s , 1, 107 (1925). \Villaman, S I L ~ Q28, Y , 409 (1926). Wiley, r.S. D e p t . Agr., Bur. Chem., Bull. 93 (I'JOA). Willaman, IND.E s o . CHEM.,20, 701 (1925). Zerban and Freeland, Lotiisiana Expt. % I . . / 3 r i l / . 166 L1019).
IQ24,,
Acetonedicarboxylic Acid as a Leavening Agent' Edwin 0. Wiig I..\BORATORII:S OF CESERAI. CHEMISTRY, UXIVERSITY O F U'I~COSSIS X I A i > r s u s .
UTHORITIES disagree as to thr physio1op;ical actioii of the products left by baking powders in baked goods. Inasmuch :is all cnniiiion bakiiig powders leave saline cathartics, such as sodium tartrate, Iiochelle salt, disodium acid phosphate, or sodium sulfate, and since there is some question as t o the physiological effect of aluminum hydroxide, :i leavening agent that w-oultl leave no residue woii.ld precludc the possibility of any controversy aiitl would constitute an ideal baking powder. Some time after the completion of a study of the kinetirs of tlie decomposition of acetonedicarboxylic acid, it occurred to the author that this substance might serve as a leavening agent, since it readily decomposes into carbon dioxide.
A
Preparation and Testing rlcetonedicarboxylic acid was prepared by adding fuining sulfuric acid to citric acid ( 2 ) . The resulting acetonedicarboxylic acid was crystallized from ethyl acetate several times and then dried over calcium chloride. Cornstarch or other starch was dried by heating under reduced pressure in a flask on a steam bath. Starch and acetonedicarboxylic acid were then weighed and mixed so as to give a baking Presented before t h e Division of Agricultural a n d Food Chemistry a t t h e 77th Meeting of t h e American Chemical Society, Colt!rnbus, Ohio, April 29 t o May 3, 1929.
\\'IS.
ponder which noultl yield from 13 t o 15 per wilt carboii dioxide, the usual strmgtli of a coniniercial baking powder. Cukes, and in one caw, bread, were then baked using a commercial baking powder and some acetonedicarboxylic acid baking pn~vder. The same recipes were uscd and thc bailie oven condition^, the two products generally being liaketl side by side. I n every case the acetonedicarboxylic acid ponder r a i w l the product a s wc11 ah the cornmereid powder. Esperimeiitb iwre carried out to determme bhether t ~ rI l ~ t acetone was left in the product. A cake 1e:~vencdwith acetonedicarboxylic acid baking powler wah run tlirougl1 n food chopper, n-hich %as subsequmtly c~rrfullywasheti with water and the washings added to the ground c a k ~ A thin paste was made of the cake by adding a litrr of matc.1 and then steam-distilled until 200 to 300 cc. of distillat(, collected. A few d r o p of sulfuric acid were added to tlw distillate, which was then distilled until 30 cc. were collected On adding 10 cc. of this distillate to 25 cc. of a haturatetl solution of 2,4-dinitrophenylhydrazine in 2 ;V hydrochloric acid, no precipitation was obtained, while 0.005 cc. of acetoncl in 10 cc. of water gave a heavy precipitate. Hence not more than a trace of acetone can possibly be prewit, since it i\ readily volatilized at baking teinperatiire,i. Furthermore, small amount* of acctonc are knnn.n to be harmless ( 2 ) .
I N D U S T R I A L A N D ENGINEERING CHEMISTRY
1146
All of the acetone, however, was not volatilized from the one sample of bread which was baked, for the characteristic odor of acetone was strongly evident. Stability
Several preliminary experiments have been conducted to determine the stability of acetonedicarboxylic acid baking powder a t various temperatures. According to the literature acetonedicarboxylic acid decomposes in a few hours a t room temperatures. However, in the course of a study (3) of the kinetics of the decomposition of acetonedicarboxylic acid, weighed quantities of the acid that were allowed to stand in a desiccator over phosphorus pentoxide from March to October showed no decomposition. Several samples of acetonedicarboxylic acid baking powder were kept in stoppered glass bottles a t various temperatures for some time. The available carbon dioxide was then determined by boiling a 1.5- to 2.0-gram sample with water and absorbing the gas in potash solution. The apparatus used was essentially the same as that used in determining the available carbon dioxide in a baking powder. The data obtained are given in Table I. The carbon dioxide a t the beginning of the experiment was calculated from the percentage of acid mixed with the starch, except in samples 1 and 2, in which the carbon dioxide was actually determined. Table I-Available
Carbon Dioxide i n Acetonedicarboxylic Acid Baking Powders
1 SAMPLB TIME TEMPER.4TURE
1
Days 43
C. 32.2“ 23.96
L
43
32.2= 23.9b
3
105
23.9
4
70
23.9
5
;;
6
72 72
2i.9 23.9 0
AVAILABLE CARBONDIOXIDE Calcd,
Calcd. to 155; availatAe COz powder
At start
end
F. 90 75
Per cent 14.00
Per cent 13.69
Per cent 11.36
Per cent 12.17
;!
14.00
13.66
11.11
11.91 13.40
a
I ;: I 75 32
1
At
at
;$p‘
13.00
12.60
11.61
15.00
14.53
12.56
12.56
13.00
12.52
11.24
12.98
13.00
12.52
11.24
12.98
a refrigerator for more than 2 months, no carbon dioxide being obtained. The results have been calculated to a 15 per cent available carbon dioxide powder as shown in the last column in Table I. The data indicate that mixtures made up to give 15 per cent carbon dioxide would contain more than 12 per cent (the legs1 minimum) after standing a t room temperatures for 1 year. Samples 3 and 4 have been kept a t room temperature for 17 and 142/3 months, respectively. The percentage of available carbon dioxide was then determined by titrating the undecomposed acetonedicarboxylic acid with tenth-normal alkali. Sample 3, which originslly contained 13 per cent available carbon dioxide, was found to have 9.2 per cent a t the end of 17 months, while sample 4, which originally had 15 per cent carbon dioxide, still contained 11.3 per cent a t the end of 142/3 months. Calculations from both samples indicate that a powder containing 15 per cent available carbon dioxide a t the start would contain 12 per cent a t the end of 12 months. Conclusion
Most baking powders are “double-acting;” that is, a part of the carbon dioxide is liberated on mixing the batter and the remainder on baking. Acetonedicarboxylic acid decomposes only slightly in the batter unless some of the ingredients are heated. This can be overcome by adding a small amount of sodium bicarbonate, sodium carbonate, ammonium carbonate, or other slightly alkaline salt which, in the kinetic study previously referred* to, were found to catalyze the decomposition of acetonedicarboxylic acid. However, this would leave the catalyst in the baked product, which it is desired to avoid. Furthermore, the acetonedicarboxylic acid baking powder raises cake sufficiently without a catalyst. An acetonedicarboxylic acid baking powder might be manufactured to compete with the more expensive baking powders on the market, especially if cheaper citric acid is made available. Such a powder would have the advantage of leaving nothing in the baked product. The study of the suitability of acetonedicarboxylic acid as a leavening agent is being continued with the aid of the Wisconsin Alumni Research Foundation,
Day.
a
Vol. 21, No. 11
Literature Cited
b Night.
In a refrigerator the acid does not decompose a t all or a t least only very slowly. This was shown by blowing nitrogen through bottles of the baking powder that had remained in
communication. Loevenhart, (2) Marvel, “Organic Syntheses,” Vol. V, p. 6 , John Wiley & Sons, Inc., New York, 1925. (3) wiig, J. phys. Chem., 32, 961 (1928).
Sampling Cleaned Apples for Determination of Arsenical Spray Residue’ J. W. Barnes and C. W. hlurray IjUREAU OF
T
CHEMISTRY
A N D SOILS,
u. s. DEPARTMENTOF AGRICULTURE, WASHINGTON, D. c.
H E results of an investigation of the variation of arsenical residue on individual apples as taken from the orchard conducted to find the size of sample necessary for an accurate determination of arsenical residue were AND published in the February, 1929, issue of INDUSTRIAL ENGINEERIXG CHEMISTRY.The results of analyses of apples which had been passed through apparatus designed to remove this residue, or a t least to reduce it to less than 0.01 grain of arsenic trioxide per pound of fruit, the official British toler1
Received August 17, 1929.
ance, are reported in the present paper. For apples direct from the orchard a sample of approximately 50 was found necessary, but for cleaned apples it seemed probable that a much smaller number would be adequate. Three lots of apples-one from Virginia, one from Washington, and one from Oregon-were obtained. These apples had been cleaned according to regular commercial methods in standard apparatus. Those in two lots had been washed in acid solution and those in the third lot had been wiped in a scrubber of the revolving brush type. Sixty apples were
