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ILLUMINATING GAS-For a cell of sufficient size to produce 9401.4 X 6 (volts) = 56.41 kw.-mo. Allowing 25 per cent (14.10) for interruptions, 70.51 kw.- a ton of magnesium in 720 hrs., 50,000 cu. ft. of illuminating gas would be required to form a reducing atmosphere above mo. would be required for the production of 2000 Ibs. FREIGHT AND HAKDLING OF RAW MATF,RIAIB--T~~ p h t t the electrolyte. would be within a few miles of the source of the raw material, COST O F PRODUCING 1 TONOW MAGNESIUM hence freight and handling would be a comparatively small Crude MgCIz.6HzO Il.ltonsat$30.00 $ 333.00 Commercial hTHiCl 11.1 tons a t $60.30 ........... . .. .. .. .. .. .. .. .. 67.00 item of expenqe. For each ton of metal produced, 18.85 Commercial NaCl 1.64 tons a t $7.00 . . 11-48 Oil for dehydration 5.02 bbls. a t $1.80 . . . . . . . . . . 9.04 tons of material would need to be freighted and handled. Illuminating gas 50,000 cu. ft. a t $0.50 . . . . , . . . . . 25.00 LABoR-Six men, including a chemist, would handle the Electric power 70.51 kw.-mo. a t $4.00. . . . . . . . . . 282.04 Oil for heating cell 5 tons a t $10.00 proposed plant. Anode carbon 200 Ibs. a t $0.04 .. .. .. .. .. .. .. .. .. .. 50.00 8.00 and handling of raw OIL FOR HEATIKG csLI.-The crude oil for outside heating Freight materials 18.85tons a t $5.00 . . . . . . . . . . . . 94.26 6 men, including a chemist . . . . . . 1000.00 of the cell would be required, a t most, during one-fourth of Labor the run. For this heating 5 tons would be required. TOTAL .............. $1879.81 CARBON AIioDEs--,kbout 200 lbs. of carbon anodes would 182000 79.81 = $0.939 per Ib. to produce a ton of magnesium be consumed per ton of metal.
Loss of Carbon Dioxide from Dough as a n Index of Flour Strength”” By C. H. Bailey and Mildred Weigley DIVISIONOF AGRICULTURAL BIOCHEMISTRY, MINNESOTA AGRICULTURAL EXPSRIMENT STATION, UNIVERSITY FARM,ST. PAUL, MI”.
Flour strength studies conducted during the past quarter century have usually employed as the ultimate criterion of strength the comparative physical properties of yeastleavened loaves of bread produced on baking. I-Iuniphries and Biffin3 suggest that “a strong wheat is one which yields flour capable of making large, well-piled loaves.” Quality of the loaves is thus determined by their size or volume, and the texture and other related properties of the crumb. Baliing tests, however, are not exact procedures which yield uniform results when the same materials are employed. Judgment comes into play to a considerable extent, and experts sometimes differ in their opinion of the relative merits of different flours which are being compared. Such tests do not of necessity indicate the reasons for variations that are observed, or the methods for effecting desired improvements. For these reasons efforts have been directed toward developing more exact methods for testing the properties of flour that are of significance in this connection. The work reported in this paper represents an attempt in this general direction. PROPERTIES THAT CONSTITUTE STREWTII A consideration of the factors involved in the production of “large well-piled” loaves suggested to one of the authorsi that “the strength of flour is determined by the ratio between the rate ol production of carbon dioxide in and the rate of loss of carbon dioxide from, the fermenting mass of dough.” The absolute rate of carbon dioxide production in doughs made from different flours varies, to be sure, through fairly wide limits. When known, the rate can be varied in the desired direction, however, by adjustments in the formula, and particularly in the proportions of yeast, yeast accelerators, salt, fermentable sugars, and diastase preparations. The retention of gas is much more difficult to bring under control, since it is apparently determined in large measure by the percenhage and physical properties of the gluten proteins in the flour. Hence, in testing flours, the ratio between production nnd loss of carbon dioxide apparently becomes of practical significance, and this was the point attacked in the present investigation. Presented before the Division of Biological Chemistry a t the 62nd Meeting of the American Chemical Society, New York, N. Y ,September 6 to 10, 1921. Published with the approval of the Director as Paper No 274, Journal Series, Minnesota Agricultural Experiment Station. * “The Improvement of English Wheat,” J. Agu Sci , 2 (1907), 1 4 C. H. Bailey, THIS JOURNAL, 5 (1916), 208.
CHaRACTER OF FLOURS EMPLOYED 1K INVES’IIGA‘I’ION Two flours were employed, a “strong” flour milled from hard spring wheat, and a “weak” flour milled a t Spokane, Washington, from typical soft wheat of that region. The composition, and the baking qualities of the two flours, determined by the method previously described by are shown in Table I. The strong flour contained a materially higher percentage of crude protein, and on baking gave a loaf of larger volume and better texture than did the weak flour. The differences in these respects were considerable. As the flours mere of about the same grade, as indicated by the ash content and color score, they were well suited to a study of properties rcsponsible for variations in baking Strength. TABLE I-ANALYSES AND BAKINGTESTSOF STRONG AND WEAKFLOURS ExpanCrude Volume simMois- Protein of eter ture (NX5.7) Ash Loaf Color Tex- Test MARK Percent Percent Percent Cc. Score ture Cc. B878, weakflour 10.88 8.00 0.52 1200 97 85 520 Composite,strongflour 8.95 12.00 0.56 1580 98 100 910
.... ..
That the two flours also varied widely in colloidal properties was established by the procedure developed by Gortner and Sharp,5 in which the change in viscosity of ii mixture of water and on the addition of normal lactic acid solution is traced by a iLIacR/Iichael viscosimeter. Table I1 gives the results of this testUEQuite evidently there are decided differences in the properties of these two flours which are responsible for variations in the viscosity of such preparations. The 11-VISCOSITY I N MACMICHAEL DEGREESOF FLOUR AND WATER MIXTURESOF WEAKAND STRONG FLOURS (Mixture contained equivalent of 25 g. dry matter f 100 cc. water) Normal Lactic Weak Flour Strong Flour Acid Added (B878) (Composite) cc. Degrees MacMichael Degrees MacMichael 68 0.0 32 0.5 73 32 1.0 104 38 1.6 135 43 161 2.0 50 183 2.5 53 196 3.0 56 212 4.0 60 22 1 5.0 61 222 6.0 62 222 8.0 62 21 9 10.0 fil
TAB&
III6 “The Physicochemical Properties of Strong and Weak Flours. Viscosity as a Measure of Hydration Capacity and the Relation of the Hydrogen-Ion Concentration to Imbibition in the Different Acids.” Presented before the.Division of Physical and Inorganic Chemistry a t the 62nd Meeting, A. C . S., New York, N. Y., September 6 to 10, 1921. 8 Determinations made by Paul F. Sharp.
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flour which is regarded as “strong” 011 the basis of the baking tests gives a much more viscous preparation when mixed with water and lactic acid than does the weak flour. JfETHOD O F
DETERMINING LOSS OF CARBOX DIOXIDE FROM DOUGH
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the end of the absorption period by titration with standard hydrochloric acid solution. The titration data were c d culated over into terms of milligrams of carbon dioxide. It was customary in these experiments to collect the gas given off during a period of exactly 30 min., then to switch
The two flours were mixed into doughs with a mechanical dough mixer, using the following formula: Flour. ..........
....
...................... ......................... .. ............. .......................
Yeast... Salt.. Sugar. Water..
Grams 350.0 4.25 5.25 8.75 Sufficient
The water used in preparing the weak flour dough was equivalent to an average of 56 CC. per 100 g. of flour, while with the strong flour an average of 61.4 cc. per 100 g. of flour was used. These proportions of water resulted in doughs of as nearly the same consistency as could be produced with flours of such different properties. Two series of determinations were made with these doughs. I n the first. the dough was divided into aliquot part9, and the determination of the diffusion of carbon dioxide out of the dough was begun without any preliminary fermentation. Such doughs are referred to in the following discussion as “no previous fermentation” doughs. After removal from the mixer, the othcr serics of doughs were allowed to ferment for several hours in a thermostat a t 28” C. before the diffusion of carbon dioxide was determined. These doughs are designated as “normally fermented.” The fermentation period varied somewhat, averaging 274 min. in the case of the strong flour and 248 min. in the case of the weak flour. During this period the doughs were “punched” or worked lightly three times. At the end of the period the doughs were regarded as ready for molding into loaves, and were accordingly kneaded vigorously on the bread board to remove as much as possible of the occluded gas. In both series the doughs were weighed, and three aliquot portions were scaled off, each repmsenting one-seventh of the total dough, or 50 g. of flour. All three portions were subjected to the same treatment with respect to kneading and molding. The first was dropped into a 1000-cc. measuring cylinder which contained 600 cc. of water and its volume W R S determined by the rise in the water level. The second portion was molded into a cylindrical form and placed in a dry 250-cc. measuring cylinder where its subsequent volume could be determined as fermentation proceeded. The third portion was molded to fit B shallow iron pan, about 7 cm. in diameter and 1.8 cm. deep, This quantity of dough filled the round pan about level full when firmed down. The pan was covered with a ground glass plate in an inverted dialyzer. The plate and the neck of the dialyzer were fitted with tubes as shown in Fig. 1. Both tubes were tightly sealed in place with wax and, when the glass plate was vaselined and seated, constituted the only means for the passage of gases into and out of the apparatus. The entire apparatus was placed in an air thermostat maintained a t 34’ C. (93.2” F.). The inlet tube in the plate was connected to a source of moist, COz-free air a t 34’ C. (This air had been bubbled through 50 per cent sodium hydroxide solution, and then through water into a large cylinder where it attained the temperature of the thermostat before entering the dialyzer or fermentation chamber.) The outlet tube WRS connected to a Truog’ tower as modified by Bailey,8 where the carbon dioxide was absorbed in a known amount of barium hydroxide solution. The residual barium hydroxide was determined a t THISJOURNAL, 7 (1915), 1045. “Respiration of Shelled Corn,” Minnesota Agricultural Experiment Station, Technical Bulletin 3. 7
8
I
;i
\
+
l o absorotlon To&;
FIG. CHAMBER AND DOUGHARRANGEDFOR DETERMINATION OR Loss OF CARBON DIOXIDEDURING FGRMENTATION
the outlet tube to another Truog tower, where the gas was collected for another 30-min. period. During the second period it was possible to determine the residual barium hydroxide in the first tower, and recharge it for the third 30-min. period. In this way two towers served for the determination by 30-inin. periods of the gas diffusing out of each dough until it definitely “fell” or partly collapsed. At the end of each period the volume of the dough in the graduated cylinder was noted, and these values, minus the initial volume of the same dough, represented the increase in volume due to retention or occlusion of the gases of fermentation. The maximum volume attained by each dough was recorded. RELATION OF STRENGTH TO GAS RETENTION Table I11 and Figs. 2 and 3 give the average data obtained wit$ the strong and weak flours. From five to nine replicates are included in each set of averages in the table. Two series of comparisons are thus afforded: (a)The loss of carbon dioxide from the doughs per unit of time, and (6) the expansion of the dough per unit of time. The graphs establish the fact that the weak flour dough consistently lost more carbon dioxide per unit of time than did the strong flour dough. The largest relative difference is found a t the end of 120 min. in the doughs not previously fermented when the strong flour dough had lost a total of only 56.6 mg. of carbon dioxide in expanding 140 cc., while the weak flour dough had lost a total of 113.0 mg. of carbon dioxide in expanding 120 cc. Less difference in the loss of carbon dioxide per unit of time was found when the strong and weak flour doughs fermented normally were compared. Such differences as existed were uniformly in the direction of smaller losses from the strong flour dough. The total losses of carbon dioxide up to the time of falling or collapse of the two doughs were apparently about the same in both cases, but owing to the dificulty in judging of the exact time when such a collapse or fall occurred, it was impossible to determine with precision the total loss of gas up to that time. The general shape of the curves, the distance between them, and the quantity of gas lost up to the
Feb., 1922
THE JOURNAL OF INDUXTRIAL AND ENGINEERI,VG CHEMIXTRY
point where the curves begin to “break” or change shape sharply appear of more significance than the quantity of gas lost up to the time of apparent collapse of tthe dough.
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strong flour dough. Thus when the normally fermented strong and weak flour doughs had expanded 80 cc. they had lost 30 and 42 mg. of carbon dioxide, respectively, and when they had expanded 120 cc. they had lost 50 and 100 mg. Even greater differences between the two flours are observed when the doughs not previously fermented are compared.
CHANGES I N EXPANSION AND GAS RETENTION OF DOUGH
