S e p t . , 1916
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
t h e permanganate, and t h a t , for laundry purposes, this coloration was of no consequence. Subsequently, when t h e writer’s report became available,’ the contention was made b y a representative of one of t h e prominent alkali manufacturers t h a t t h e pink color was due not t o t h e presence of permanganate, b u t of a ferrate; and in order t o settle definitely the whole matter, the absorption spectrum of t h e pink bleaching solution was compared with t h a t of a solution of potassium permanganate of t h e same color intensity. The solution used was made four times t h e concentration* usually employed and, after all t h e precipitate had settled, a saccharimeter tube was filled with the clear pink solution. A similar tube was filled with potassium permanganate solution of same color intensity and the absorption spectra were compared; t h e y were found t o be identical. T o compare t h e t w o more carefully, t h e two absorption spectra were brought in view a t one time, b y means of the comparison mirror, and t h e positions of t h e lines v-ere shown t o be exactly the same. No a t t e m p t is made here t o account for t h e presence of t h e trace of manganese in t h e bleaching powder, b u t t h e writer feels t h a t he has offered positive evidence t h a t t h e color of t h e pink bleaching solutions is due t o t h e presence of sodium permanganate, and not of sodium ferrate, as some have maintained. MELLONINSTITUTE
OF I N D U S T R I A L
RESEARCH
PITTSBURGH
ON THE USE OF CERTAIN YEAST NUTRIMENTS IN BREAD-MAKING3 By HENRYA. KOHMAN, CHARLES HOFFMAN, T R U M A N M. GODFREY, LAUREN H. ASHE, AND ALFRED E. BLAKE Received June 7 . 1916
T h e work in bread-making a t t h e Mellon Institute was begun in 1911 through the establishment of the Ward Fellowships and t h e results will now be published in a series of contributions. One of t h e important problems studied in our bread investigations mas the effect of certain mineral salts (such as are commonly found in natural waters) upon t h e fermentatiT-e activity of t h e yeast in breadmaking. I t was found necessary b y t h e Ward Baking Company (who operate bakeries in several cities) t o change t h e quantity of yeast as well as t h e fermentation period of their dough batches in the different cities, in order t o produce a standard product, or nearly so, even though all t h e raw materials used were identical (being purchased through a central office). Upon investigation it was found t h a t variations in t h e activity of the yeast were due t o the differences in t h e mineral content of t h e waters used for making t h e bread in these cities. In t h e work reported in this paper t h e effect of mineral salts found in natural waters upon the fermentative power of the yeast, as well as t h e quantity of yeast necessary for leavening purposes, has been given particular attention and 1 T h e conclusions were reported b y bulletin t o t h e Allegheny County Laundrymen’s Exchange on April 17, 1916. 2 T h e solution of sodium hypochlorite was prepared with 40 6. of commercial calcium hypochlorite, 40 g . of soda ash, and 40 g. of sodium bicarbonate, made u p t o a volume of 250 cc. with distilled water. 8 A paper presented in abstract b y Henry A, Kohnian a t the Urbana Meeting of the American Chemical Society, April 19, 1916.
781
close investigation. The mineral substances contained in flour, milk, yeast and other raw materials for bread mere investigated in detail also, using a large variety of combinations and proportions. Of t h e large number of substances investigated. those t h a t have a really significant effect upon t h e fermentation in bread are surprisingly few. The salts of t h e mineral acids, such as the chlorides, nitrites, nitrates and sulfates, exert practically no influence except when combined with a cation which in itself has an effect. The carbonates are especially common i n natural waters and as a class are objectionable in bread, since t h e y neutralize the acids of the dough and thus interfere with t h e progress of t h e fermentation. More particularly, t h e carbonates of magnesium and the alkali metals should be considered as being detrimental t o the fermentation of t h e yeast. T h e salts of potassium, particularly the phosphates, were expected t o exert a decided influence on t h e fermentation of bread, because these compounds constitute such a large proportion of the ash of yeast a h d are mentioned so frequently in connection with alcoholic fermentation. Hoyever, the potassium salts were found t o influence the fermentation of bread only very slightly, while the phosphates had no noticeable effect. This is t o be explained, no doubt, b y the fact. t h a t t h e ash of flour is rich in these salts, consisting of about one-third potash ( K 2 0 ) and one-half phosphoric acid (P205),which abundantly supplies t h e yeast. Because of their common occurrence in natural waters, t h e salts of the alkaline earth metals were studied in detail, with surprisingly interesting results. T h e calcium salts, especially, are of common occurrence in water and it is around these t h a t t h e most interesting results presented in this paper center. Besides t h e water problem, t h e utilization of stale bread was indicated as an important problem for research. One of the proposed methods for using stale bread comprised t h e cooking of t h e crumbs and t h e n digesting with malt. The starches were thus transformed into sugars and t h e gluten remained in flakes which could be separated b y filtration. From this gluten residue, by digesting with concentrated HC1 in the ordinary way, glutamic acid hydrochloride was recovered in considerable quantities. The effect of the glutamic acid upon the parent substance, gluten, in bread was found t o be a decidedly beneficial effect both upon t h e dough and upon the yeast. AiiIUONIUM SALTS
Like many other acids, glutamic acid matures or ages t h e dough and, in addition, increases the gas production of t h e yeast. This accelerating effect upon the yeast was observed in bread and likewise in fermenting cane sugar, dextrose, and malt extract. I n fermentation of this kind other acids failed t o increase t h e fermentation as did glutamic acid hydrochloride, so we were led t o believe t h a t it was not a matter of acidity but t h a t glutamic acid hydrochloride owes its accelerating effect t o its nitrogen content. With this idea in mind, we conducted baking experi-
T H E JOCRLV.IL O F I N D U S T R I A L A N D E N G I W E E R I N G C H E M I S T R Y
782
ments with other nitrogenous substances. Ordinary peptone, such as is used for culture media, as already known, accelerates alcoholic fermentation greatly b u t this substance is expensive and. accordingly, attention was directed toward cheaper materials which would accomplish a similar result. The salts of ammonium were found fully as efficient as peptone. Before giving t h e experimental d a t a , it should be said t h a t during t h e course of this investigation, which extended over a period of several years. the conditions were changed from time t o t i m e ; consequently, the results of a n y particular series of baking experiments can not be compared strictly with those of another. Every precaution was taken, however, t o maintain the same conditions throughout each series. so that the individual loaves cou!d be compared closel>- with the control and with each other. In each series of experiments the loaves were scaled, moulded, proofed and baked together. Therefore, when accelerators were added the loaves naturally had not all risen t o the same height when they were piaced in the oven, as they d o in commercial baking practice. Consequently, the volumes given in t h e tables are an expression of the rate of fermentation rather than of t h e relative lightness or degree of expansion t h a t may be obtained. For example. when thcrc was. say: a I O per cent increase in volunie noted with the use of an accelerator, i t does not mean t h a t thc expansion was increased b u t merely t h a t t h e rate of fermentation was increased b y t h a t amount. If t h e two loaves had been brought t o the same degree of maturity and proofed t o the same height in the pans. as is customary in baking practice, both loaves would have conformed t o the standard size. I n many bread lahoratories. also, it is customary t o proof all t h e loaves t o the same height, especially when t h e volumes are taken to represent t h e expansion, as is t h e case in testing flours. In the experiments of this paper, however, all t h e loaves of each series were baked simultaneously, so the volumes should be interpreted as indicating t h e rate of t h e fermentation rather t h a n the expansion of the loaves. The following series of experinients will serve t o illustrate the effect of ammonium sulfate upon t h e yeast in bread-making. A liilogram of flour TVX used in cach batch BREAD
No. 646
.
&~, A i.
648 649 650 65 1
Grams (NHI)&OI 0.0
LOAF
0 9
1790
1,5
1865 1870 1930 1900
2.5 3.5
4.5
Cc. 1630
VOLUME
7cIncrease 0.0 0.8 14.4
14. i 18.4 16.5
Cc. Gas Per cent Gas in ?I/%hrs. Increase 292 0.0 311 6.5 6.5 310 329 12.6 328 12.6 338 15.7
Besides increasing t h e gas production and improving and securing a more uniform loaf volume, t h e ammonium sulfate improved t h e texture and t h e general uniformity and appearance of the bread. The gas production mas estimated b y taking a small portion ( j o g.) from each dough and collecting t h e gas evolved over a saturated solution of calcium chloride in Bunsen gas holders. In a cane-sugar medium, ammonium sulfate also greatly increased the fermentative power of yeast.
Vol. 8 .
KO.o
,4 series of seven fermentation experiments was made. using 68 g. of water, 1.2 g. of yeast and 6 g. of sugar, with varying amounts of ammonium sulfate. Tllz results were as follows: Experiment No 1 0.0 Grams (NHa)*SOa.,, Gas, cc. in 61/2 hrs ... 291 Per cent increase.. , , 0.0
2 3 0.25 0.5 358 364 230 25.1
4 5 1.0 2.0 392 447 34.8 53.7
6 ; 4.0 8.0 457 155 5 7 . 2 -46 S
While readings were taken every half hour, t h e total gas produced will serve t o illustrate t h e accelerating action of ammonium sulfate. I t will be noted that 8 g . has a marked retarding action. Early in the research it was observed t h a t the increased fermentation, due t o ammonium sulfate, matured the doughs in a much shorter time. Bread fermented 3 1 , 1 2 hrs. with the use of ammonium sulfate was practically as mature as t h e control bread in 4‘12 hrs. Obviously. then. this salt can be used for the production of bread in a shorter time. On firsr thought, one might infer t h a t this action would be taken advantage of in increasing the output of ;I bakery; this, however, is not the case. The over. capacity, more t h a n anything else, governs the productive power of a bakery. Although a short fermentation period is highly desirable in the bake shop, there is a limit beyond which it is not safe t o go. Unforeseen delays are frequent in the daily operations, and since these often occur when t h e dough is already working, over-fermentation is t h e result. The shorter t h e fermentation period. t h e greater will be t h e overfermentation when delay occurs. I n our opinion. according t o present practices, t h e fermentation period should not be less t h a n 41/2 t o j hrs. for hard wheat flours, excepting, of course. in special cases in which i t is necessary t o produce bread in a very short time t o meet rush orders. I n general, t h e increased fermentation due t o t h e addition of ammonium sulfate can best be utilized b y reducing the amount of yeast t h a t is ordinarily required. The following series of baking experiments serves t o illustrate t h e value of this salt in the diminution of yeast requirement: BREADNo. 193 (control) 198 194 196 197
GRAMSYEAST 12.0 9 . 0 (25% less) 8 . 4 (30y0 less) 7 . 8 (35 % less) 7 . 2 (40% less)
VOLUMEOP LOAP (Cc.) Fermented: 31/2 hrs. 41/2 hrs. S1/t hrs. 1695 1735 1745 1815 1875 1805 1665 I755 1795 1655 1705 1805 1695 1795 1645
I t is abrious t h a t the amount of yeast t h a t can be saved b y t h e use of ammonium sulfate depends upon t h e length of time t h e dough is fermented. I n a 41/2-hr. dough (41,2 hrs. is the time adopted in many bakeries for straight doughs), 30 per cent of the usual amount of yeast can be saved. while the saving in yeast in a jl/’rhr, dough is 40 per cent. Various processes are in use in different bakeries and the length of t h e fermentation period ranges from 3 l / > hrs. t o 6 or even 8 hrs. in straight doughs and from 5 t o I O or 1 2 hrs. in t h e sponge-dough process. The fact t h a t t h e ammonium salt accelerates t h e activity of t h e yeast most toward the end of t h e fermentation period is considered significant. It is then t h a t gas production is most essential, for it causes t h e loaves t o “spring” or “kick,” which is very desirable and
Sept., 1916
T H E J O l * R S d L OF I N D V S T R I A L A N D ENGINEERING CHEMISTRY
necessary for t h e production of a loaf with a fine close texture. good color and flavor. Especially is t h e “spring” desirable in t h e special types of loaves which are cut lengthwise, for it opens a n d ventilates t h e m properly and gives t o t h e t o p of t h e loaves a fine shredded appearance t h a t is inviting a n d appealing t o t h e sight a n d taste. I n referring t o good color here, it must be borne in mind t h a t excessive fermentation will destroy such good color, as is reasonable t o expect, dependent on t h e grade or quality of flour used, while proper fermentation will save or spare it. Other ammonium salts t h a n t h e sulfate may be used with equally good results. We have employed t h e chloride, phosphate, biphosphate, t a r t r a t e , oxalate, nitrate, acetate, formate, iodide, a n d sulfocyanate, a n d have observed no pronounced difierences. However, for economic reasons, t h e sulfate a n d chloride are considered most suitable for commercial purposes. Because of its alkaline properties, ammonium carbonate can not be used successfully, as is shown by t h e following baking experiments: Bread No... . . . . . . . . . . . 1653 0.0 Gram (NHa)zCOs., . . . . . . . Loaf volume, cc.. . . . . . . . . 1505 0.0 Per cent increase. . . . . . . . .
1654 0.24 1560 +3.3
1655 0.5 1530 +1.6
1656 1. O
1445 -3.9
I n small quantities. t h e volume remains practically unchanged, while it is diminished by I g. or more. Alkalies are very detrimental i n bread a n d this, no doubt, explains t h e inefficiency of ammonium carbonate. Moreover, i t was observed t h a t ammonium carbonate imparted an objectionable odor t o t h e bread. T h e carbonate may be used successfully only when sufficient acid is used t o neutralize its alkalinity. Ammonium fluoride accelerates t h e fermentation quite as much as other ammonium salts if used in small quantities; but in larger quantities it retards fermentation t o a marked extent, as is evident from t h e following series of experiments: Bread No.. . . . . . . . . . 847 848 849 851 852 850 0.0 0.1 G r a m s NHaF.. . . . . . 0.2 0.4 0.8 1.6 1850 1955 Loaf volume, cc.. , , . 1690 1930 1400 2080 0.0 10.0 15.7 P e r c e n t increase . . . . 23.1 1 4 . 1 -17.1 0.14 Acidity.. . . . . . . . . . . 0.13 0.14 0.13 0.15 0.14
Evidently ammonium fluoride can not be used in as large quantities as ammonium sulfate, for, with t h e latter, t h e maximum acceleration was not exceeded even when 4.j g. were used, while with t h e fluoride t h e maximum effect was obtained with less t h a n I g. I n small quantities, however, t h e acceleration b y ammonium . fluoride is more pronounced, i n equal weights! t h a n t h a t by ammoniiim sulfate, t h e explanation of which, no doubt. lies in t h e great difference i n t h e molar weights. The inhibiting effect characteristic of ammonium fluoride in large quantities was also noted with hydrofluoric acid. Three doughs of t h e usual size were made with respectively I , 2 and 4 cc. of hydrofluoric acid solution and none of t h e m rose. Sodium fluoride is not so detrimental, as may be seen from t h e following results: B r e a d N o . . . . . . . . . . . 1338 GramsNaF. . . . . . . . 0.0 Volume, cc . . . . . . . . . . 1515 Per cent increase.. , . 0.0
1339 0.1 1555 4-2.6
1340 0.2 1525 +0.6
1341 0.4 1485 -1.9
1342 0.8 1475 -2.6
1343 1.6 1505 -0.6
The diminution in volume observed in this series is not significant,
783
C A L C I U M SALTS
The results of our experiments with calcium salts, which have already been mentioned in connection with their occurrence in natural waters, will now be t a k e n u p in detail. Their effect will be given both when used alone a n d in conjunction with other salts. T h e effect of calcium chloride is indicated in t h e following table: 612 613 614 610 611 Bread No.. . . . . . . . . . 609 3.5 4.5 1.5 2.5 0.0 0.5 Grams C a C l z . . , , , , . 2090 2110 2040 2070 1935 Loaf volume, cc.. . . . 11830 14.2 15.3 11.4 13.1 0.0 5.7 Per cent increase, . , 380 393 391 385 361 G a s , . . . . . . . . . . . . . . 348 Per cent increase.. .
0.0
9.1
3.7
12.3
12.9
10.6
There was a decided increase in volume a n d gas production with t h e increase in t h e calcium chloride content of t h e doughs. The texture, flavor, a n d general appearance of t h e bread were improved, as well. The loaf volume was increased considerably more t h a n t h e gas production, which would indicate t h a t calcium chloride has a n effect upon t h e gluten of t h e dough as well as upon t h e yeast. I n t h e light of some experiments conducted b y H a r d y upon t h e effect of electrolytes on the strength of wheat flour, this seems highly probable. The effect of calcium chloride upon t h e fermentation of cane sugar is shown in t h e table below. I n each of t h e six experiments, I O O g. of water, I O g. of sugar, a n d 2 g. of yeast were used. Experiment No.. . . . . 1 (control) 2 3 4 5 6
Grams CaClz.. . . . . . 0 . 0 Gas in 612! hrs.. . . . , 3 4 4 Per cent increase . . . . 0 . 0
0.5 391 $13.6
1.0 408 +18.6
2.0 418 +21.5
4.0 429 +24.7
8.0 281 -18.2
The accelerating effect of calcium chloride in bread, like t h a t due t o ammonium salts, can best b e t a k e n advantage of b y reducing t h e amount of yeast ordinarily used. As with t h e use of ammonium salts, t h e amount of yeast t h a t can be saved depends upon t h e length of t h e fermentation period. I n a 41/2-hr. dough, about 2 5 per cent of t h e yeast can be saved. The effect of other calcium salts is very similar to t h a t of t h e chloride. T h e results given! below with calcium bimalate indicate t h a t it is equally effective. Bread h-o . . . . . . . . . . . . 573 Grams calcium bi. 0.0 malate . . . . . . . . . . . . Loaf volume, cc.. . . . . 1770 0.0 P e r cent increase . . . . .
574
575
0.5 1850 4.5
576
577
1.5 2.5 3.5 1970 2005 2020 11.3 13.3 14.1
578 4.5 2110 19.2
T h e increase in volume is even greater t h a n with calcium chloride. However, as calcium bimalate is slightly acid, t h e two salts are not strictly comparable. The sulfates of calcium i n t h e following series of experiments, in which CaS04.2H20 a n d CaS04 1 / 2 H 2 0 were compared in molar quantities, increased t h e volume rather less t h a n t h e chloride, especially with t h e larger quantities. BREAD iSC.
3916 (control) 3917 3918 39 19 3920 3921 3922 3923 3924 3925 (control)
Grams CaSOa.2HzO 0.0 0.5 0.0 1.0 0.0 2.0 0.0 4.0 0.0 0.0
Grams CaSOc1,‘rHzO 0.0 0.0 0.422 0.0 0,844 0.0 1.688 0.0
3.376 0.0
LOAFVOLUME
Cc. 1670 1710 1723 1726 1796 1863 1826 1830 1853 1676
Increase 0 .o 2.4 3.2
3.4 7.6 11.5 9 . . .4
9.6 -11.0 0.4
I n t h e following series of experiments t h e sulfate
7 84
T H E JOCRN.4L O F I l V D U S T R I A L A N D En'GIiZ'EERISG C H E M I S T R Y
and chloride were compared carefully, using small quantities: BREAD NO.
GRAMSSALTS 0.0 1 CaCh 1 CaSOI. 1, tHzO 2 CaC1z 2 CaS04.'/zH?O
LOAF\'OLUhlE % Increase n o
cc. 1830 I915 1945 2045 2065
Time Control 1643
9:40 0 0
v01. 8. S O .9
GAS PRODUCED DURING VARIOUSPERIODS 10:40 11:40 12:50 1:50 2 . 5 0 3 : 5 0 TOTAL 55 6i 85 89 i4 7; 447 cc . 28 43 62 73 75 80 361 cc
I t will be noticed that dough 1643 (with jo per cent of the usual quantity of yeast, I g. of CaCl? and 0.5 g. 11.7 of (NH4)&304) evolves gas only about half as rapidly 12.6 as the control in the initial fermentation, b u t t h a t after I n each case it will be noticed t h a t the sulfate gives 6 hrs. it exceeds the ,control in the rate of gas proa slightly larger loaf volume. I n small quantities, duction. This is indeed significant. for it is a t the then-say, about 2 oz. per 60 lbs. of mater? or apend of the fermentation period when thc dough has proximately 160 lbs. of bread-the sulfate gives been moulded into loaves t h a t active production of equally good, if not better results t h a n the chloride. gas is required and most needed. If the yeast vzeakens I n practice there is used not more t h a n z oz. per 160 when the dough is in the proof box or oi-en, the bread lbs. of bread and as calcium chloride, on.ing t o its will not have the "spring" necessary to produce a extremely hygroscopic nature, can not be used satiswell-risen loaf with a good shape and texture. factorily. because i t can not be conveniently shipped I n this connection, it should be mentioned t h a t or kept in t h e dry state, t h e sulfate is preferable for others have experimented with ammonium salts in commercial use. connection with research on flours. J. T. Willard and The nitrate and phosphates of calcium have also been C. 0.Swanson' found t h a t ammonium chloride proused successfully. Of the phosphates, C a ( H 2 P 0 4 ) ? duced a beneficial effect on the baking qualities of and CaHP04 are most suitable, as the normal salt is flour, while the phosphate had no effect. and t h e both alkaline and difficultly soluble. tartrate and acet,ate had a detrimental effect upon the Since both calcium and ammonium salts accelerate texture. The application of ammonium chloride or fermentation and improve bread, experiments were other ammonium salts t o effect economies in yeast in made with both salts in conjunction n-ith breadconnection with bread-making are not mentioned i n making. The results of one series of experiments t h e report of those investigators. were : A. J. J. Vandervelde, L. Bosmans. F. Le Perre. j. BREAD Gram Grams LOAF VOLUME Mason and 4. Revigu2 state t h a t ammonium chloride NO. (NH4)zSOc CaClz cc. yo Increase 548 (control) 1800 0.0 0.0 0.0 and nitrate have only a slight action and t h a t calcium 1800 549 0.5 0.0 0.0 1985 550 0.5 10.1 0.5 nitrate exerts a very unfavorable action. In our 2050 55 1 1.5 13.9 0.5 opinion, the quantities used were excessive, and. more552 2065 2.5 14,i 0.5 553 21 15 3.5 17.5 0.5 over, such discrepancies in the literature on bread 554 li.7 2120 4.5 0.5 Thirty per cent less yeast was used with these salts. are not uncommon and are t o be explained. n o doubt, It will be seen t h a t in conjunction with ammonium by inaccuracy in experimentation and by the fact t h a t sulfate calcium chloride gives a further increase in t h e so many factors, such as temperature, age of dough. loaf volume. Since this was found t o be true, a series strength of flour, stiffness of dough. etc.. affect the of experiments was made t o determine horn much results; consequently, they are often misinterpreted yeast could be saved b y the use of both salts in bread. and important results are sometimes overlooked. T h e fact t h a t the initial fermentation with yeast The results were as follows: LOAFVOLUME Mean Per cent nutriments with a reduction in the L I S L I ~ amount ~ of BREAD Grams Gram Yeast Fermented: Loaf Increase NO. CaCh 9H4C1 Used 3'12 hrs. 41!2 hrs 51;~hrs. Vol. in 1'01. yeast is much slower than that of a normal dough has 1820 1890 18i5 0.0 0 . 0 Sormal 1915 (control) 0 . 0 a n interesting economic significance. I t is well known 1920 2070 1995 6.4 0.0 0 . 5 30qb less 2000 2270 2365 20.2 2255 2.0 0 . 5 30y0 less 2130 t h a t during the normal fermentation of bread there is a 13.1 2165 2195 2120 2.0 0 . 5 4OYc less 2000 11.7 2060 2270 2095 2.0 0 . 5 SOY0 less 1965 considerable loss of dry material, due t o the decom1910 1.8 2.0 1880 2055 0 . 5 60% less 1800 position of t h e constituents of the dough into volatile With both salts, as with the use of an ammonium products. These losses as determined by various salt alone, t h e amount of yeast t h a t can .be saved investigators are: lroorhees,3 4.3 per cent; Heeren:3 depends upon the fermentation period employed. 1.57 per cent; Fehling,3 4 . 2 1 per cent; C r ~ e g e r ,2~. 1 4 After 3 1 / 2 hrs. fermentation, only j o per cent of t h e per cent; Jago,* 2 . j o per cent; and Snyder and Voornormal amount of yeast could be saved without a h e e ~ 2, ~t o 6 per cent or even 11 per cent, in cases of sacrifice in loaf volume! while after 4l/2 hrs. 60 per prolonged fermentation. cent could be saved. After j1/2 hrs. fermentation, One of us, in a previous paper,G demonstrated t h a t t h e batch with 60 per cent less yeast produced a loaf the losses in bread-making depend t o a large extent rolume t h a t was decidedly larger t h a n t h e control, upon the amount of fermentation which the dough indicating t h a t still more yeast could have been saved. undergoes. I n a normal fermentation the losses were The fact t h a t t h e gas production is greatly increased found t o be 5.15 per cent, while with the same flour toward the end of t h e fermentation period by the 1 Kansas Agr. Exper. Sta., Bull. 190, 248-251; E x P . Sla. KEcovd yeast nutriments: wa's observed also by collecting t h e March. 1912, 356. gas from 6 0 - g . portions of two doughs oaer a 2 Reo. gln. chim., 16, 123. 136. 3 U. S. Dept. 4gr.. Office of Experiment Stations, Bull. 36. saturated solution of calcium chloride in Bunsen gas 4 Jago, "The Science and A r t of Bread-Making," p. 361 holders. The follbwing d a t a will serve t o illustrate 5 U. S. Dept. Agr., Bull. 67, 11 and 28. 6 Kohman. THIS J O U R N A L , 4 (1912), 20--30 and 100-106. this point: 1060 1061 1062 1063 1064
4.6 6.2
T H E J O G R N A L O F I N D U S T R I A L A N D E N GI A’ E E R I N G C H E M I S T R Y
Sept., 1916
t h e total losses were only 1.81 per cent, when t h e loaves were placed into pans a t once upon mixing. The bread obtained in this way was decidedly poor, as is always t h e case when i t is very much underfermented, a n d i t was made i n this way merely t o detect a n y difference in losses due t o fermentation. I n salt-rising bread t h e losses were found t o be only 0.44 per cent. This difference in t h e losses in t h e t w o types of bread was explained as follows: ( I ) Yeast produces 1.04 p a r t s of alcohol for every p a r t of carbon dioxide, both of which are largely driven off during t h e process of baking, while in salt-rising bread there is no alcohol produced. ( 2 ) It is necessary t o ferment yeast bread in t h e sponge a n d dough stages from j t o 8 hrs., a n d , as it is allowed t o rise in loaf form in t h e pans b u t one hour or less, only a small p a r t of t h e total gas produced is actually used in aeration, while salt-rising bread is made into loaves a n d placed in t h e pans immediately upon mixing t h e dough a n d very little gas is lost. ( 3 ) The gases produced b y yeast consist of carbon dioxide, while those produced by t h e salt-rising bacterium consist of about carbon as heavy dioxide and 2,’3 hydrogen, which is only as t h e former. The fact t h a t t h e losses in ordinary bread are dependent upon t h e amount of fermentation led us t o suspect t h a t with t h e use of yeast stimulants t h e decomposition of sugar would be less t h a n in a normal dough, because t h e initial fermentation is much slower and t h e total gas production is less. With this idea in mind, we made three normal doughs a n d three with a reduction of 50 per cent in t h e usual amount of yeast and with 0 . ; g. ammonium sulfate a n d 1 . 2 g. calcium chloride in 1000 g. of flour. T h e gas evolved in t h e usual time f r o m jo-g. portions of t h e doughs was collected in Bunsen gas holders, a n d from t h e total weight of gas produced t h e quantity of sugar decomposed was calculated, assuming t h a t t h e carbon dioxide evolved represented 4j per cent of t h e loss in sugar. T h e results of these experiments are given below:
1 ;;%
BREADh-0. Controls
“4Cl and CaClz
1139 1136 1138 1140
Cc. GASFORMED 396 404 ? A v . 403 409 J
%: } Av. 345 348
PER CENT Loss I N SUGAR Calculated on Flour
::::]
4.39 3.58
1
L32 1
Av. 4 . 3 3 Av.3.70
DIFFERENCE
0.63
I t will be noticed t h a t t h e consumption in sugar is considerably higher in t h e control dough t h a n in t h e one with added salts. The difference represents t h e saving in sugar t h a t is effected b y the use of ammonium a n d calcium chlorides in bread. U S E OF P O T A S S I U M B R O M A T E
In connection with t h e use of these salts as yeast nutriments in bread-making, with special reference t o t h e losses, mention will be made briefly of potassium bromate as used in conjunction with them. The functions of t h e latter salt will be more fully treated in a subsequent paper, inasmuch as it is not a yeast nutriment b u t acts upon t h e dough, imparting t o it very desirable properties. I n t h e fermentation of bread, a twofold object is
785
accomplished; namely, the maturing, or aging, of t h e dough, a n d t h e aeration of t h e bread. The former is accomplished during t h e fermentation period, which takes from 4 t o 6 hrs. i n t h e best practice, a n d t h e l a t t e r during t h e proofing period, which requires from t o I h r . After t h e dough is sufficiently matured, or aged, it passes through t h e dividing a n d moulding machines, which press out practically all of t h e gas. Then i t is p u t into pans a n d allowed t o proof, a n d only t h e small fraction of t h e total gas which is produced while t h e bread is in t h e pans actually functions in aerating t h e bread. T h e effect of t h e potassium bromate upon t h e dough is essentially an aging, or maturing, effect and is characterized b y t h e exceedingly small quantities required. The following series of experiments will serve t o illustrate t h e changes in loaf volume with increasing quantities of potassium bromate : Bread No . . . . . . . . . . . . . . gram^ potassium broma t e . ,, . . . . , , , , . . . . . , Loaf volume, cc. . . , . , , . Percentincrease . . . . . . .
4547 0,000 1735 0.0
4548 0.015 1785 ‘218
4549
4550
4551
0.030 1755 +1.1
0.060 1605 -7.4
0.120 1375 -21.3
The maximum volume occurs with 0 . 0 I j g. per batch of 1000 g . of flour, a n d i t will be noticed t h a t with 0.06 a n d especially with 0 . 1 2 0 g. there is a marked diminution in volume. This influence upon t h e loaf volume is not due t o a n y change in t h e rate of fer. mentation or gas production, b u t t o t h e pronounced aging, or maturing, effect of the salt upon t h e dough itself. Similar changes in volume are effected by varying t h e amount of fermentation t o which t h e dough is subjected. Up t o a certain point, t h e gasretaining power of dough and t h e loaf volume are increased b y fermentation; t h e n t h e dough becomes “rotten,” i . e., i t no longer retains t h e gas well a n d , accordingly, t h e volume is greatly reduced. A desirable quantity of potassium bromate-say 0.01 5 g. per batch of dough containing 600 g. of waterages t h e dough so decidedly t h a t 2 5 or 30 per cent of t h e usual amount of yeast can b e saved without imparting t o t h e bread a n y of t h e characteristics of underfermentation, such as heaviness, dark color a n d coarseness in texture. I n fact, t h e bromate in these quantities improves t h e bread with respect t o texture even though t h e yeast is reduced by 2 j per cent. This pronounced effect is attributed t o t h e oxidizing power of this salt, for it has been found t h a t b y passing oxygen through t h e dough a similar maturing action is obtained, b u t t o a lesser degree. This is probably one case we due t o t h e condition of t h e oxygen-in have molecular oxygen and in t h e other we have nascent oxygen-the nascent oxygen being more powerful t h a n t h e molecular, a n d , therefore, would have a greater maturing action on t h e dough. The effectiveness of t h e nascent oxygen is indeed surprising, for t h e quantity of t h e potassium bromate is so small t h a t t h e total available oxygen is less t h a n I cc. per loaf of bread. When potassium bromate is used in addition t o ammonium a n d calcium salts, it effects a saving in yeast of 2 j t o 30 per cent of t h e amount required without i t . For instance, when jo per cent of t h e usual
T H E J O U R N A L O F I N D U S T R I A L AiVD E N G I N E E R I N G C H E M I S T R Y
786
amount of yeast can be saved with t h e yeast stimulants, t h e saving may be increased t o 65 per cent with t h e addition of potassium bromate. T h e aging, or maturing, effect of potassium bromate upon t h e dough, without increasing t h e rate of fermentation or t h e sugar consumption b y t h e yeast, results in a much greater saving in sugar t h a n t h a t due t o t h e yeast stimulants alone. T o determine this saving, three normal doughs were made a n d three with 0 . ; g. ammonium sulfate, 1.2 g. calcium chloride, a n d 0.015 g. of potassium bromate i n 1000 g. of flour a n d 35 per cent of t h e usual q u a n t i t y of yeast. T h e gas evolved from 50 g. portions of t h e doughs was used as the basis for calculating t h e losses in sugar due t o fermentation. The results of these experiments may be t h u s summarized:
Controls New Process
1
PERCENT Loss IN SUGAR Calculated on Flour 5.64 6.15 A v . 5.98 6.15 3:62 1 Av. 3 . 6 2 3:62 J DIFFERENCE . . . . . . . . . . . . . . 2.36
Cc. G a s FORMED 415 Xv. 440 452 452 J 225 Av. 266
BREADNo.
1
2237 2238 2239 2240 2241 2242
1
56;
I
1
T h e results of a similar series of experiments are tabulated below; these show t h e losses a t t h e end of 5 , 6 a n d 7 hrs.. respectively. GAS IN Cc. 5 6 7 hrs. hrs. hrs. 309 373 435 310 375 440 312 379 442
BREADNo. 2251 Controls 2252 2253
i
Average
,, ,,
.,
.
2254 2255 2256 Average
.......
---
310 184 177 178
375 250 239 240
439 322 302 309
Diff. in Loss Cc. Gas Loss in Sugar between New & between Per cent Old Process 6 t h & 5 6 7 5 6 7 7 t h hrs. hrs. hrs. hrs. hrs. hrs. hrs. 62 5 . 2 6 6 . 3 4 7.44 65 5 . 2 6 6 . 3 8 7.50 63 5 . 3 0 6 . 4 2 7.50 -
- --
64 72 63 69
5.27 3.12 3.00 3.02
6.38 4.25 4.07 4.07
7.48 5.44 5.10 5.25
- - __
-
-- __
180 243 311
68
3 . 0 4 4 . 1 3 5 26
2 23 2 25 2 22
Six hours’ fermentation is t h e approximately normal period in t h e best baking practice, 5 hrs. in t h e dough s t a t e a n d I hr. after t h e bread is made u p into loaves. T h e range between j a n d 7 hrs. fermentation will cover most variations in baking processes, due t o t h e requirements of different flours a n d t h e t y p e of bread desired. It is clear from t h e results cited above t h a t t h e losses increase as t h e fermentation proceeds and t h a t t h e y are uniformly lower in t h e new process. T h e differences in t h e average losses between t h e two processes are 2 . 2 3 , 2 . 2 j , and 2 . 2 2 per cent in 5, 6 and 7 hrs., respectively, which is practically a constant. This is t o be explained b y t h e fact t h a t after j hrs. t h e rate of fermentation in t h e two processes is practically t h e same. T h e difference in decomposition of sugar occurs mostly in t h e initial stages of t h e fermentation before the nutriments greatly accelerate t h e activity of t h e yeast. I n another series of experiments, t h e losses were determined by direct weighing, as had previously been done b y one of US,^ a n d also b y collecting t h e gas. Both batches were set with 1000 g. of flour, and, after mixing, were divided into two equal portions. Onehalf was used for t h e determination of t h e losses b y weighing a n d from t h e other half three portions of 4 0 g. each were taken by collecting t h e gas. The 1
Kohman. LOG.CZL.
Vol. 8. No. g
results given in t h e following table represent the mean of t h e three results obtained: MOISTURE-
FREEMATEBREADNo.
RIALPUT
LOSS
DRY
INTO BATCH BREAD G r a m s
2340 (Control).. . 494.78 g. 458.7 g. 3 6 . 0 8 2341 (New Process).. 493.75 g. 469.7 g. 24.05
PERCENT
LOSSBY
GAS COLLECTION 3 : 3 0 P.M. 4:OO P.31. 7.21 6.12 6.59 Per cent
4.81
3.98
4.38
The losses’ were calculated from t h e gas collected a t 3 : 3 0 o’clock, when t h e bread was put into t h e oven, a n d again a t 4 : 00 o’clock, when i t was t a k e n out. The fermentation was completely arrested between t h e two times, of course, a n d t h e results obtained b y direct weighing can more strictly be compared with those calculated on t h e gas a t 4 . 00. Rather lower results were obtained b y collecting t h e gas t h a n b y direct weighing. The solution of gas In t h e liquid of t h e dough may in part account for this a n d it is also suggested t h a t t h e losses may not be due entirely t o t h e decomposition of sugar b y t h e yeast. However, t h e agreement is fairly close, showing t h a t most of t h e material lost is due t o t h e destruction of sugar b y t h e yeast. Sugar analyses were made of breads prepared with and without added salts a n d t h e results afford additional confirmation of t h e destruction of sugar by t h e yeast. Three batches were made, one each b y t h e two processes with t h e regular amount of sugar a n d one b y t h e new process with 2.25 per cent less sugar (calculated on t h e flour), which represents t h e difference inasugar consumption by t h e two processes, as determined b y collecting t h e gas. The results follow: PERCENT SUGAR I N BREADCALCULATED O N FLOUR CONTROL WITH ADDEDSALTS Nor. Sug. (25 g.) 2.25% less Sugar Fermentation Normal Sugar (25 9.) 1.70 3.41 2 70 5 1.56 3.02 I 96 i .61 2.66 1.37
Hrs.
6
It will be noticed t h a t with t h e normal amount of sugar a n d added salts t h e bread is much richer in this substance t h a n t h e control, while if 2.2j per cent less sugar is used in t h e batch, t h e bread is slightly richer in sugar t h a n t h e control bread. T o confirm t h e reduction in t h e destruction of fermentable material in bread by t h e use of t h e new process. gas-collection experiments were conducted in a large bakery where i t is in operation. Three portions of j o g. were taken from each of t h e two doughs ( 1 6 0 0 lbs.) set b y t h e new and old process, respectively. T h e losses, representing t h e mean of t h e three determinations, were as follows: PERCENT New Process 0.24 0.43 0.55 0.69 0.82 1.10
1.38 1.64 1.84 2.25 2.49 2.81 3.03
Loss SUGAR
Old Process 0.39 0.69 0.97 1.27 1.58 1.96 2.36 2.68 3.13 3.48 3.85 4.18 4.35
PERCENTSUGAR S4VED 0.15 0.26 0.42 0.58 0.76 0.86 0.98 1.04 1.29 1.23 1.36 1.37 1.32
TIME Hours
The difference in t h e destruction of sugars in these 1 It is assumed t h a t t h e carbon dioxide represents 45 per cent of the sugar destroyed by t h e yeast.
S e p t . , 1916
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING CHEMISTRY
experiments was 1.37 per cent at t h e time t h e bread was removed from t h e oven, which was considerably less t h a n t h a t obtained i n t h e laboratory. This, we think, is due to t h e fact t h a t less yeast in proportion t o t h e dough batch is required i n t h e bakery. It is common practice t o use about twice as much yeast in laboratories as is required in bakeries t o mature dough in t h e same time. This is t o be explained in p a r t , a t least, b y t h e fact t h a t a batch of 1600 lbs. rises from 3 t o 6" C. i n temperature, due t o t h e fermentation, while a small batch containing 1000 g. of flour remains practically constant in temperature. T h e authors have frequently observed a difference i n temperature of j t o 6 " C. between t h e center a n d outside of a large dough batch. This is attributable, n o doubt, t o t h e evaporation of water on t h e surface of t h e dough, as t h e temperature of t h e room is t h e same as t h a t of t h e dough a t t h e time of its setting; naturally, t h e n , t h e cooling effect will be much more pronounced in t h e case of a small dough. T h e small amounts of dough ( 5 0 g.) t a k e n for collecting t h e gas from t h e large mass of 1600 lbs. in t h e bakery, would be especially subject t o this cooling effect. Hence, we are inclined t o regard the. results obtained in t h e laboratory as nearer t h e t r u t h t h a n those obtained in the bakery, particularly when i t is common knowledge t h a t much higher proportions of yeast are required in laboratory batches. T h e curves i n Fig. I illustrate graphically, t h e losses in bread-making due t o t h e destruction of sugar. By means of t h e curves, t h e losses can be calculated a t a n y desired time, which is impossible in determining t h e losses b y direct weighing. In connection with t h e determination of t h e losses i n bread-making, i t should be mentioned here t h a t t h e method involving t h e collection of t h e gas given off from a n aliquot portion of t h e dough batch is novel. An a t t e m p t was made t o estimate t h e consumption of t h e sugars i n bread b y making sugar determinations upon t h e dough a t intervals as t h e fermentation proceeded. Such determinations were made upon largescale doughs set both b y t h e old a n d new processes. Sugar determinations were also made upon sample loaves of bread t h a t were taken from t h e batches a t intervals a n d allowed t o rise t o t h e usual height i n t h e pans a n d baked. The results are given in t h e following table: 7 -
Time 9 : 50 11 : 50 I : 55 3 : 30 5 : 05
-
PER CENT SUGARCALCULATED ON FLOUR DOUGH BREAD-------Old New Old New Process Time Process Time Process Time Process 5.21 9 : 30 4 . 7 2 12 : 00 5 . 3 2 1 : 10 4 . 8 2 5.67 1 1 : 40 5.16 1 : 10 5 . 1 4 2 : 25 4 . 5 8 5.22 1 : 30 5.44 3 : 20 4.12 3 : 50 4 . 3 5 5.13 3 : 05 5 . 2 9 5 : 00 3 . 4 7 4 : 45 4.22 4.27 4 : 55 4 . 8 8
-_--
I t is interesting t o note t h a t for several hours there is a n increase in t h e sugar content of 'the dough, t h e old process reaching a maximum about z hrs. after , t h e dough is set a n d t h e new one at about 4 hrs. I n t h e light of this fact, i t is evident t h a t sugar analyses upon dough can not serve as a n index t o sugar consumption b y t h e yeast. T h e results are of interest, however, i n demonstrating t h e activity of diastatic enzymes. I n t h e new process t h e sugar content is higher a t t h e
787
e n d of t h e fermentation period t h a n at t h e beginning, showing t h a t t h e production of sugar is greater t h a n t h e consumption; in t h e old process, this does not obtain, as there is nearly I per cent less sugar at t h e end. T h e difference i n t h e sugar content between t h e two doughs a t t h e beginning is due t o t h e fact t h a t less sugar is regularly used in t h e new process.
FIG.I-LOSS
IN
BREAD-MAKING C4LCULATED
FROM
Cot EVOLVED
T h e curves in Fig. I1 present graphically t h e changes in sugar content of t h e doughs during t h e fermentation period. As t h e curves cross, i t is demonstrated clearly t h a t although I per cent less sugar was used in t h e new process, t h e bread baked after the usual fermentation period was actually about I per cent richer in sugar t h a n t h a t made b y t h e old process.
FIG. 11-CHANGESI N SUGAR CONTENT
The economic saving possible by t h e proper use of nutrient salts, in t h e advent of a rather general adoption, sums u p t o surprising figures. Take, for example, t h e saving in sugar on t h e average flour 2 0 million production of t h e S t a t e of Kansas-say barrels, or nearly 4 billion pounds. A saving of z per cent on this amount is 80 million pounds; and i t is mainly sugar t h a t is decomposed and t h u s lost in bread-making. The economies in t h e yeast are greater t h a n those in t h e sugar. Even a moderate use of such a process means a considerable saving t o t h e country a n d is a step towards conservation of resources. At t h e present time, this process is used commercially in t h e manufacture of more t h a n a. million loaves daily. A further advantage incident to this process of breadmaking was observed in t h e increased stability a n d stiffness of t h e dough. T o one familiar with doughs this is easily discernible t o t h e touch; it was also determined more accurately a n d with numerical d a t a b y means of t h e dough viscosimeter (see Fig. 111). The viscosimeter consists essentially of a cylinder having a graduated piston which forces t h e dough through a n aperture a t t h e bottom. The stiffer a n d more tenacious t h e dough, t h e slower is t h e descent
788
T H E J O U R N A L OF I Y D C S T R I A L A N D E N G I N E E R I Y G C H E M I S T R Y
Vol. 8, Yo. 9
b y t h e new process just as it does in t h e usual process. By a n y process, t h e color of t h e c r u m b is improved b y fermentation u p t o a maximum and in t h e new process t h e same changes are noted; much less yeast, however, is required t o accomplish t h e desired results. The practical application of t h e new process has met with success a n d it is now in operation in a large number of bakeries. A number of these are under t h e direction of one superintendent. who claims t h a t t h e process has been of material aid in standardizing t h e manufacture a n d maintaining uniformity of t h e bread in t h e different localities. As already s t a t e d , certain differences were noticed in t h e bread in a chain of bakeries. Control New Process although all t h e raw materials were identical. These 2395 2396 B R B A D N O. . . . . . . . . . . . . . . . . . . . . 2391 2393 2394 6.3 61 62 60 Percent wafer ................. 60 have been practically overcome by t h e new process. li 9 vireority . . . . . . . . . . . . . . . . . . . . . . 13 21 18 which virtually standardizes t h e water used f o r t h e The control with 6 0 per cent of water is decidedly baking purposes. This would be expectcd. because lower in viscosity t h a n No. 2393, which has t h e same t h e required nutriment is supplied by means of these a m o u n t of water. I t will be noticed, further, t h a t t o salts used as yeast food. a n d t h e addition of f u r t h c r obtain a dough of normal stiffness a n d stability. from mineral matter, either through t h e water or otherwise, 2 t o 3 per cent more water may be has less a n d less effect as t h e quantities increase. I t added, another evidence of t h e con- is a general rule t h a t . in t h e addition of nutrimcnts or servation of flour in t h e dough batch activators in steps, the first portion added has a from t h e use of these yeast foods. correspondingly greater effect t h a n t h c succeeding T h e resistance t o softening of flour portions. during t h e progrcss of t h e fermentaFor t h e sake of convenience and accuracy in t h e use tion is of great significance in t h e of these salts, t h e y are in practice mixed with flour manufacture of bread. a n d t h e greater a n d salt, so t h a t it requires 8 oz. of t h e mixture f o r stiffness and stability ohtained by t h e 6 0 Ibs. of water, or approximately 160 Ihs. of bread. new process is a valuable feature. An average bakery batch ( 1 2 0 0 t o ijoo loaves) conDuring t h e fermentation of the tains about 480 Ibs. of water. which requires 4 Ibs. of dough, t h e gluten is softened a n d t h e yeast food, a quantity t h a t may be conveniently partially broken down b y t h e yeast weighed with accuracy. The product has also heen as well as gas a n d alcohol being prepared as a liquid. in which case t h e salts are disformed from t h e sugar. T h e differ- solved in water, so t h a t 8 oz. of t h e solution for 6 0 Ibs. ence in sugars decomposed between of water deliver t h e required amount. For t h e d r y t h e old process a n d t h e new process product t h e sulfate of calcium is preferred. while in t h e is a b o u t 2 per cent when figured on solution t h e chloride is used. The use of either product t h e flour used. B y using t h e new introduces about 2 oz. of a calcium salt, a little less process, we are t h u s able t o decrease t h a n I oz. of ammonium chloride a n d 0 . 0 2 oz. of t h e q u a n t i t y of flour used by. 2 per potassium bromate into t h e hatch for 60 Ibs. of water cent a n d still have a dough of t h e used or f o r 160 Ibs. of bread. I n practice, t h e yeast same stiffness. T h i s p r o b a b l y food is first dissolved in t h e water used in t h e dough accounts for t h e fact t h a t in t h e batch. Pro. 111 bakery we can use I . j per cent more I t is h u t natural t o inquire: W h a t becomes of t h e water or are able t o decrease t h e amount of flour 2 chemicals during t h e fermentation a n d baking of t h e per cent a n d still have a dough of t h e desired or usual bread? T h e purpose of t h e ammonium salt, as alstiffness. ready stated, is t o supply t h e nitrogen required by t h e The new process has been used f o r breads of various yeast a n d it is of interest t o know whether a n y of i t types, such as pan breads, Vienna a n d French breads; remains in t h e bread. also, for. rye, Graham a n d whole-wheat breads. LikeT h e following table. showing t h e analyses in public wise, it has been used with spring, winter a n d Kansas laboratories of five commercial breads of greater flours, a n d t h e different grades of flour. a n d has been Boston, will answer this question. found t o he universally applicable. RESULTS (PER canr) OP ANALYSES OF VAnlous B R B A D S o Moisture Ash Lime (CaO) SO1 Ammonia W H - ) I n connection with t h e different grades of flour, it B a i ~ No. 0.037 n.nnsx 0.026 I . . . . . . . . 40.12 1.16 I I . . . . . . . 40.19 1.04 0.029 o.ni6 0.0044 should he said t h a t t h e process can not be used t o give 0.022 0.00.3: 1.14 n.ni9 I11 . . . . . . 41.29 bread the appearance of being made from a higher 0.014 o.on11 0.017 Iv ....... 38.31 0.93 V ........ 11.116 1.05 0.01s 0.019 0.0069 grade of flour t h a n is actually employed. The im. Bread No. I was made b y t h e new process and it provement in color with t h e use of t h e new process is not as high in ammonia as will he observed t h a t it is due t o t h e improvement in texture a n d can not be ., without yeast nutriments. None of t h e regarded as a bleaching process. The grayish c o l o ~ No. I,made of t h e lower grades of flour remains in t h e bread made breads has a n ammonia content t h a t is at all significant.
of t h e piston. T h e time t h a t elapses while t h e piston descends t h e distance between t w o chosen marks is determined b y means of a stop-watch. This reading in seconds represents comparative viscosities of t h e doughs, I n t h e s t u d y of flours, t h e authors have found t h e viscosimeter very valuable. Five doughs were made, four b y t h e new process a n d a control. T h e water content of t h e four doughs was varied between 6 0 a n d 6 3 per cent, while t h e control was made with 60 per cent water. The viscosities, which represent t h e mean of five readings a n d t h e percentage of water used, are tabulated below:
Sept., 1916
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
Additional analyses in our own laboratories confirm t h e above results. I t will be noticed, also, t h a t No. I 1 is higher in lime t h a n KO.I. T h e s t a t e of combination of t h e calcium in t h e bread is scarcely subject t o question. I t has been shown b y Teller’ t h a t t h e phosphoric acid in flour exceeds b y t e n times t h e calcium a n d it may be safely said t h a t , even b y t h e use of t h e new process, t h e bread contains several times as much phosphoric acid as is required t o combine with t h e calcium. Under these conditions, t h e potassium phosphate of the wheat undoubtedly interacts with t h e calcium sulfate, as it does in wort,2 in accordance with t h e following equations:
+
KHIPOl CaS04 = CaHP04 z K 2 H P 0 4 3CaS04 = Ca3(PO4)2
+
+
+ KHSO4
-I- 2KHSO4
I t is known3 t h a t t h e calcium requirements of t h e body can be supplied b y inorganic as well as b y milk calcium. Abderhalden4 has demonstrated t h a t t h e complicated organic substances of our foods are replaceable b y t h e simplest structural materials a n d t h a t these are built u p into various tissue substances. It should be mentioned in connection with t h e use of calcium salts in bread t h a t Rudolph Emmerich a n d Oscar Loew’ advocate t h e use of calcium salts i n bread from a purely dietetic standpoint. I n fact, t h e deficiency of calcium in our food is indicated clearly in Experiment Station Record, 2 0 , 6 8 . A detailed discussion of this subject, with special reference t o white bread. was published recently b y one of us.6 The increased lime content of bread b y the use of t h e new process is a very happy coincidence, even though incidental. Unfortunately, in modern methods of milling, t h e greater part of t h e mineral constituents of wheat is lost t o white flour. As indicated b y Teller,7 seven-eighths of t h e phosphoric acid a n d elevenfourteenths of t h e potash a n d lime of wheat are found in t h e stock feed; consequently, a partial restoration of t h e lime in white bread must be considered h.ighly desirable. COKCLUSIONS
I-By t h e use of minute quantities of ammonium a n d calcium salts a n d potassium bromate i n bread, from jo t o 6 j per cent of t h e usual amount of yeast can be saved. 11-Incident t o t h e economy in yeast t h u s effected, there is a saving of about 2 per cent of fermentable carbohydrates, calculated upon t h e total flour used, due t o t h e greatly diminished consumption of these b y t h e yeast. 111-The proper use of nutrient salts for t h e yeast gives greater control over t h e dough batches a n d aids in t h e production of better a n d more uniform bread, regardless of t h e locality, Ark. Agr. Expt. S a . , Bull. 42, 7 0 . Matthews’ “Manual of Alcoholic Fermentation,” pp. 194 and 195. 3 Biochem. Z., 9, 185-207. 4 Wzen. med. Woch., 69, 177. 5 Z. H y g i e n e , 1 7 , 31 1-28. e Kohman. Bakers’ Reuiew, 31 (1914). 61-62. 7 Ark. Agr. Expt. Sta.. Bull. 42. 1
Il‘-The
789
added salts conserve t h e inherent qualities
of t h e .dough a n d consequently maintain its stability a n d strength t o a far greater degree t h a n by t h e old process. Y-The finished loaves are improved in quality, flavor, texture, bloom a n d uniformity. MELLONIKSTITUTB UNIVERSITY OF PITTSBURGH
A STUDY OF THE SYRUP PRECIPITATE IN WHITE SUGAR MANUFACTURE By CHARLESE. COATESA N D L. C. SLATSR
Received May 9, 1916
Although t h e manufacture of white sugar direct f r o m t h e cane has been carried on t o some extent in Louisiana for nearly a century, for certain reasons this industry has lately taken on a new lease of life a n d a t t h e present time is of great importance. T o such a degree is this true, t h a t most of t h e larger Louisiana sugar houses are now equipped for t h e direct manufacture of white sugar without t h e intervention of t h e bone-black refinery a n d in many instances have installed apparatus which has proven valuable in t h e manufacture of beet sugar. The experience of t h e las, few years, however, would indicate t h a t there are not only different chemical difficulties t o overcome, but also certain mechanical differences in t h e manufacture of white granulated beet sugar a n d cane sugar, which make special detailed attention t o t h e latter exceedingly necessary. For instance, leaving aside t h e important question of clarification, i t has become evident t h a t filtration of t h e clarified cane juice is imperative, b u t t h e method of filtration a n d t h e number of fi trations are points still somewhat in dispute. Some sugar houses allow t h e clarified juice t o settle a n d pass t h e decanted, clear juice through bag filters. Occasionally t h e filtered juice is filtered again before final evaporation, b u t ordinarily i t passes direct t o t h e effects, where it is evaporated t o a Brix of from 50 t o 5 5 ” . There is considerable difference of opinion as t o t h e proper subsequent treatment of this syrup. Sometimes a little sulfur dioxide or phosphoric acid is added t o restore t h e initial acidity, b u t usually t h e syrup is passed into t a n k s , where it is allowed t o settle from 2 t o 4 hrs., gradually falling in temperature during t h a t time. When t h e syrup is finally drawn from t h e t a n k s , there is always t o be found a precipit a t e , which is separated as well as possible by decantation. I n certain houses t h e a t t e m p t has been made t o filter t h e syrup through leaf presses. This gives a bright filtrate, b u t t h e process, being tedious and expensive, is ordinarily dispensed with, though something is always removed from t h e syrup. If what it removes does no h a r m in t h e subsequent manufacture of white sugar from t h e cane i t is evident t h a t syrup filtration could be safely omitted and t h e cost of manufacture lessened. T h e syrup precipitate is probably not present in t h e solid form in t h e freshly evaporated syrup, inasmuch as i t will f o r m in t h e course of several hours in syrup which has been previously filtered, h o t , through paper.
