July, 1918
T H E JOCR,VAL OF I N D C S T R I A L A N D ENGI-VEERING C H E M I S T R Y
Vr -
X 273 X
P R E P A R A T I O S O F SAMPLE
0.001965
760 a n d call this t h e constant for the apparatus, K . We then have : KP W t . of coz = 273 t T h e percentage of COZin t h e carbonate t h e n follows, thus IOO K P Percentage of COz = (273 t ) X Wt. of sample‘ By use of logarithms t h e necessary calculation may be made in less t h a n 2 min. The total time consumed in making a determination, including t h e weighing and calculation, need not be over I j min. After completing a determination t h e capsule may be lifted out of t h e apparatus b y means of a wire hook, a n d t h e spent acid may be drawn out with a pipette. T h e apparatus is then ready for the next determination without even refilling with COZ. ~
+
+
Calcite Per cent COz 43.53 43.67 43.40 43.52
Av., 43.51 By ignition 43.59
24.71 24.34 24.67 24.36 24.59
NanCOa aq. Per cent COz 34.74 34.40
By absorption method
-
34.59 34.30
Av. 24.53 B y absorption method 24.47(a)
( a ) Average of 100 determinations varying from 24.1 per cent to 24.8
per cent. SEVERANCE CHEMICAL LABORATORY OBERLINCOLLEGE, OBERLIN,OHIO
A PROXIMATE ANALYSIS OF THE SEED OF THE COMMON PIGWEED, AMARANTHUS RETROFLEXUS L By EVERHART P. HARDINCAND WALTERA. EOGE Received August 3, 1917
I t was thought b y t h e authors of this paper t h a t t h e partially carbonized bracts of t h e seeds of this common plant might make a good filtering medium €or decolorizing sugar and other colored solutions. This suggested other possible uses of t h e seeds which led t o their proximate analysis. D E S C R I P T I O N O F PL.4NT’
This variety of pigweed is commonly called “red root,” “rough pigweed,” “green amaranthus” and “Chinaman’s greens.” I t is a n annual weed which grows from a well-formed a n d fairly deep-rooted t a p root. The root is generally red. The plant grows from I t o 3 f t . high and is branched, t h e branches coming obliquely from t h e stem. T h e stem and leaves are rough. T h e plant flowers fron; July t o September. These flowers are very inconspicuous, appearing in t h e angle formed by t h e stem and leaf stalk. The seeds are oval, black and shiny, a n d ripen during August, or before. The weed occurs in all parts of t h e State of Minnesota a n d thrives in all kinds of soil, b u t prefers a rich loam. It is common in gardens and waste places and does most injury b y crowding out crop plants. 1
p. 37.
The seeds were stripped from plants growing in Waseca County in t h e southern p a r t of Minnesota. They were cleaned b y removing foreign matter and chaff (bracts). The separation and removal of t h e bracts was difficult and tedious. Approximately 7 5 per cent of t h e seeds were black a n d fully matured, t h e rest were red, showing varying degrees of maturity. The sample was rapidly ground t o 20-mesh size and t h e moisture determined on a portion of this size t o represent total moisture in t h e seeds. The rest was air-dried for 7 days and then ground t o a 7a-mesh size. Moisture and all other determinations were made on this size sample. AKALYSIS
AND 7 2-MESH S A M P L E S - O ~ ~ gram samples were dried in an electric drying oven a t exactly 100’ C. Preliminary tests showed t h a t 14 and 4 hrs., respectively, were required t o bring the 20- and 72-mesh samples t o constant weight. MOISTURE
IN
20-
-20-Mesh-
RESULTS Argillaceous Limestone Per cent COz
529
Minnesota Agricultural Experiment Station, Bull. 129, March 1913,
I
....
I1
Moisture content, grams., 0.1127 0 . 1 1 2 9 Average percentage of moisture 11.28
-72-Mesh-
I
I1
I11
0.0860
0.0860 8.60
0.0860
AsH-Ash was determined on one-gram samples in an electric muffle a t a temperature of 620’ C. I
....................... 0.0445 ......... .....
Ash content in grams., Average percentage of a s h . .
I1
I11
0.0448 4.46
0.0446
It was very difficult t o burn t h e substance completely t o a n ash- over a Bunsen burner. D E T E R M I N A T I O K O F O I L ( E T H E R EXTRACT)-AbOUt one-gram portions of t h e material, dried respectively t o constant weight in a n air oven a n d in a vacuum sulfuric acid desiccator, were extracted in Soxhlet extractors with anhydrous, alcohol-free ethyl ether t o completion, which required 16 hrs. I Oven dried, grams o i l . . . . . . . . . . . . . . . . . 0.0798 Desiccator dried, grams oil. . . . . . . 0.0814 Oven dried, average percentage of o i l . . . Desiccator dried, average percentage of oil
I1
I11
IV
0.0793 0.0788
0.0788 0.0801
0.0791
....
7.92 8.46
The dried oil dissolved in cold sulfuric ether, b u t not in cold petroleum ether. PRoTEIK-Protein was determined b y Gunning’s modification of Kjeldahl’s method, using one-gram samples a n d t h e nitrogen conversion factor 6.2 j . I Proteincontent, grams.. . . . . . . . . . . . . . . . 0 . 1 8 8 0 Average percentage of protein. , , . , . . ,
. .
sT A R cH
DE T E R MIN A TI
I1
I11
0.1873 0 . 1 8 6 7 19.13
o N (ACI D c o N V E R SI o N
IV 0.1880
ME T H OD)
-Three-gram samples were used. The usual acid conversion1 of starch into dextrose was made and t h e amount of dextrose determined b y t h e MunsonWalker method.z The seeds occupied a volume of 2.10 cc., for which allowance was made. Aliquot parts of t h e solution equivalent t o 0.30 g. of substance were used in t h e reductions a n d t h e starch conversion factor of 0.90 was used. The following amounts of reduced cuprous oxide and t h e corresponding weights of dextrose and starch were found. ISachse, Chem. Zenlr., 1877, 732; Bureau of Chemistry, U. S . Dept. of Agriculture, Bull. 107. 2 Browne, J . A m . Chem. Soc., 1906, 439.
T H E JOURNAL OF I N D U S T R I A L A N D ENGINEERING C B E M I S T R Y
530
-I---. 1 2 CueO, mg . . . . . . . . . . 299.6 298.0 Dextrose, mg . . . . . . . 137.0 136.2 Starch, mg . . . . . . . . . 123.3 122.6 Percentage of starch 41.09
7111 2 297.5 298.4 135.95 136.40 122.4 122.7 40.91
7-111-----. 1 2 300.1 299.4 137.25 136.90 123.5 123.2 40.98
Average percentage of s t a r c h . . . . . . . . . . . . . 4 0 . 9 6
METHOD)-Threegram samples were used and t h e diastase conversion carried out as outlined in Leach’s “Food Inspection a n d Analysis,” p. 284. The Munson-Walker method was used for determining t h e amount of dextrose. The reductions were determined on an aliquot p a r t of a definite volume equivalent t o 0 . 2 4 0 g. of material. For t h e conversion 0 . 6 0 g. of commercial diastase with a reduction equivalent of 33.1 mg. of cuprous oxide was used. STARCH D E T E R M I N A T I O N (DIASTASE
CuzO, mg . . . . . . . . Dextrose, mg .....
..
starch
.........
7 1 7 1 2 233.9 234.1 89.40 89.50 80.46 80.55 33.53
33.56
Average percentage of starch
----II----. 1 2 232.8 233.3 88.85 89.10 79.96 80.19 33.32
...
7-1117 1 2 232.8 232.0 88.85 88.46 79.96 79.61
33.41
33.32
33.17
33.39
D E T E R M I N A T I O N O F S U G A R ( R E D U C I N G SUGARS)-The determination of sugar was difficult on account of the colloidal condition of t h e sugar extract. This difficulty was finally overcome b y keeping t h e solution just slightly alkaline, which seemed t o settle t h e colloids. Filtering was avoided as far as possible b y increasing t h e volume of t h e solution and pipetting an aliquot volume. Five-gram samples were boiled in 1 5 0 cc. of 5 0 per cent neutral alcohol for a n hour on a steam bath, with reflux condenser. The solution was cooled t o room temperature and t h e volume made u p t o 500 cc. with 9 5 per cent alcohol made just alkaline. After thoroughly mixing and settling over night, 400 cc. were pipetted off with continuous suction and evaporated on a water bath t o 20 cc. This volume was made u p t o 2 5 0 cc., using 2 cc. of lead acetate t o clarify. After clarifying, 2 0 0 cc. were pipetted with continuous suction into a beaker and t h e excess of lead precipit a t e d with anhydrous sodium carbonate. T h e solution was filtered a n d jo cc. of t h e filtrate used for determining t h e sugar b y t h e Munson-Walker method. From a n aliquot p a r t of t h e solution equivalent t o 0.80 g. of material only a mere trace of CuzO was formed. DETERMINATION
OF
SUGAR
(AFTER
INVERSION)-
Fifty cubic centimeters of t h e solution in t h e preceding determination from which t h e excess lead was precipitated were pipetted into a 100-cc. graduated flask, 5 cc. of concentrated hydrochloric acid added, t h e volume made up t o I O O cc. with distilled water, and allowed t o remain over night a t about z o o C. --I---. 1
CuzO, mg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.00 9.40 Dextrose, mg.. . . . . . . . . . . . . . . . . . . . . . . . . . Percentage of dextrose,. , , . , , , , , . , , , . , , . 2 . 3 5 Average percentage of dextrose.. . . . . . . . . . Percentage calculated as cane sugar.. . . . . .
2 21.40 9.56 2.39
c---II--. 1 2 21.90 21.10 9.44 9.76 2.44 2.36 2.39 2.15
The acid was nearly neutralized and t h e sugar determined in an aliquot part of t h e solution, equivalent t o 0.40 g. of material, b y t h e Munson-Walker method.
Vol.
IO,
?Jo. 7
D E T E R M I N A T I O N OF C R U D E FIBER-This determination was made on 2-g. samples containing 8 . 5 7 per cent of moisture. Kennedy’s modification’ of Sweeney’s method was used and modified b y filtering a n d igniting in alundum crucibles. Crude fiber and ash, grams..
I I1 I11 IV 0.2585 0.2650 0.2590 0.2580 0.0358 0.0380 0.0398 0.0382 0.2127 0.2220 0.2192 0.2198 10.63 11.1100 10.96 10.99 10.92
....
,
TANNIr;-Qualitative
tests showed tannin.
SUMMARY -PERCENTAGES ON20-Mesh 72-Mesh OvenCONSTITUENTS as Received Air-Dried Dried Moisture. 11.28 8.60 0.00 . . . . . . . . . . 4.33 4.46 4.88 Oil (ether extract). . . . . . . . . . 7.03 7.24 7.92 20.93 Protein. 19.13 Starch (diastase). 33.39 36.52 40.98 44.83
.................
........
F
DesiccatorDried
....
.... 8.46
.... ....
---PERCENTAGES ON-20-h.Iesh 72-Mesh OvenCONSTITU~NTS as Received Air-Dried Dried Hemicellulose (starch by acid conversion . . . . . . 7.37 7.59 8.31. . . . . . . trace trace trace Sugar (after inversion). . . . . . . . . . . . . . . . . . 2.32 2.39 2.31 Sugar (after inversion computed t o cane sugar) ....................... 2.08 2.15 2.35 Crudefiber ............................ 10.59 10.92 11.92 Tannin and other undetermined substance by difference ......................... 6.35 6.52 7.17
The proximate analysis shows t h a t the seeds would make a good component part of a stock food a n d a s seeds of related species have been found t o contain considerable amounts of potassium nitrate, t h e rather high protein content would suggest t h a t t h e y might. be valuable as a chicken or bird food. CHEMICALLABORATORY UNIVBRSITY OF MINNESOTA MINNEAPOLIS
THE DETECTION OF VEGETABLE GUMS IN FOOD
PRODUCTS By A. A. COOK AND A. G. WOODMAN Received M a y 2, 1918
The use of gums in food products is dependent mainly on their physical properties, t h e most noteworthy of which is their colloidal nature. This property enables t h e gum substance t o hold within itself relatively large quantities of water and still impart a decided “body” t o t h e mixture. Their use is specifically, then, as thickeners and binders in such food products as marshmallow preparations, ice cream, custards, pie fillings, egg substitutes, a n d flavoring emulsions. The gums ordinarily employed are gum arabic, gum tragacanth, Indian gum, agar-agar, a n d commercial dextrin. Gelatin, egg albumin, a n d . commercial glucose, as well as starch, are also used for t h e same purpose. EXISTING METHODS
The methods which have been proposed for t h e detection of this class of materials are based for t h e most p a r t on isolated reactions for a particular gum, depending on some color or solubility test of t h e crude gum itself , a n d having no -reference t o t h e detection of small amounts of t h e gum in a complex food mixture. Of t h e few t h a t are more general perhaps t h e best . 1
THIS JOURNAL, 4 (1912), 600.
