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UNITED STATES DEPARTMENT OF AGRICULTURE

Washington, D. C. vV November 27, 1922

A PHYSICAL AND CHEMICAL STUDY OF MILO AND
FETERITA KERNELS.

By Grorce L. BioweEtt, Lesiiz E. Borst, and Joun D. Bow1ine, Caitle Food and
Grain Investigation Laboratory, Miscellaneous Division, Bureau of Chemistry.

CONTENTS.

Page. Page.
Purpose of investigation.............-------- 1 | Malting of Kafir, milo, and feterita.._._..__. 5
Physical properties of kernels.........--.--- Ze ESTER. <e_. GE on ee e ea 7
Chemical composition of kernels............- Sig ost bliopraphyss3 57. ss) 525 SU Sines 3 ae 7

PURPOSE OF INVESTIGATION.

The grain sorghums are a comparatively new crop in the United
States, where they have been grown for only 25 or 30 years (2).!
At first their use was largely restricted to the feeding of farm animals.
These grains, however, are now being used in increasing quantities
for human food and various industrial purposes, and are receiving
attention from manufacturers of alcohol and starch. Feterita and
milo, which contain on an average 65 per cent of starch, seem to be
especially suitable as raw material for the manufacture of high-grade
starch by commercial processes.

As a basis for a process utilizing nonsaccharine sorghums in the
manufacture of starch and feeding stuffs, and to provide data for
engineers who may be called upon to design machinery for their
treatment, the Bureau of Chemistry has conducted a study on the
physical characteristics and the chemical composition of milo and
feterita kernels and the various parts into which they might be
separated by milling. This study is a continuation of similar work
done on the Kafir kernel, the results of which are published in United
States Department of Agriculture Bulletin 634. Milo and feterita
have the same botanical characteristics and the kernels very much
the same structure as the kafir kernel (Fig. 1). The data on corn
and kafir herein reported are taken from Bulletin 634.

1 The numbers in parentheses throughout this bulletin refer to the bibliography on page 8.
12343°—22

2 BULLETIN 1129, U. S. DEPARTMENT OF AGRICULTURE.

PHYSICAL PROPERTIES OF KERNELS.

Fifty kernels of milo and 50 kernels of feterita were measured
with a micrometer in three directions.? As the kernels lay on a flat
surface, the vertical diameter was called the thickness, the distance
from the hilum to the opposite end the length, and the dimension at
right angles to these the width. The maximum, minimum, and
average dimensions are given in Tables 1 and 2.

TABLE 1.— Measurements of 50 kernels of dwarf milo.

Maxi- Mini- Aver-
mum. mum, age.

Dimensions.

Milli- Milli- Milli-
meters. meters. meters.
Sak: 2.31 2
5.05 2.69

TRANSVERSE LONGITUDINAL

Fig. 1.—Sections of kafir kernels showing (4) germ, (B) starchy endosperm, (C ) horny endosperm.

One thousand kernels of milo weighed 33.9 grams. Therefore,
one kernel weighs on an average 0.0339 gram. Calculated from the
measurements recorded in Table 1, the average volume of these
kernels is 29.8 cubic millimeters and the surface of such a kernel is
48.3 square millimeters.

TABLE 2.— Measurements of 50 kernels of dwarf feterita.

Dimensions. ape a. age
Milli- Milli- Milli-
meteTs meters meters
IRRICKTICSS Hee a ao ies ae = ne ea ae oe at A oe Ae a a Rete oo 3.12 2.28 2.76
Misti) mi hasierdmnc ov Ho. jo pilergan alt. Tee | 4.82 3.83 4.18

One thousand kernels of feterita weighed 32.7 grams. Therefore,
one kernel weighs on an average 0.0327 gram. Calculated from the
measurements recorded in Table 2, the average volume of these

2 The feterita and milo used in this work were obtained from the Office of Cereal Investigations, Bureau of

Plant Industry, U. S. Department of Agriculture, and were identified under the following numbers:
Dwartf Milo C. I. 332 and Feterita C. I. 182.

MILO AND FETERITA KERNELS. 3

kernels. is 25.5 cubic millimeters and the surface of such a kernel is
44.9 square millimeters.
Table 3 gives the proportions of the component parts of the kernel.

TABLE 3.—Proportion of component parts of kernels.

Bran. Germ. Endosperm.
Kernels. Propor- | “Y@Fage | propor- | AVeFaBe | Propor- | Average
volume volume Pp volume
, tion of k 1 tion of |. if 1: tion of |. i 1
kernel "ealee kernel Gale, kernel mC e aeae
separated. lated). separated. lated ). separated. lated.)

Cubic mil- Cubic mil-| Cubic mil-

Per cent. | limeters. | Per cent.| limeters. | Per cent. | limeters.
COB SS ye ERR ee. oe Se Ue A edetcle ct 3D} [Rasen SU ees
VNTR Tos To Ot Sa UN 1 OM So 6.1 1.02 10. 0 1.68 83.9 14.10
SMU Coe ete Oe a See De a Oe at) 1.63 HG 3. 30 83. 4 24. 80
EME) SCE on ER SS eal NG A Ua 6.6 1.68 7.3 1. 86 86. 1 21. 93

The calculations in Table 3 are based on the assumption that the
different parts of the kernel have the same specific gravity. On this
assumption the thickness of the milo bran would average 0.033 milli-
meter, while that of the feterita bran would be 0.037 millimeter.
It is realized that there are differences in the specific gravity of these
tissues, but they are too small to affect the conclusions here drawn.

CHEMICAL COMPOSITION OF KERNELS.

Table 4 gives a comparison of the composition of the whole kernels
of the kafir, milo, and feterita, on a water-free basis.

TaBLE 4.—Comparison of composition of kafir, milo, and feterita kernels on a water-

Sree basis.
Propor- Nitrogen-
Kernels. tion of Ash. ee Protein. Grade free ex- Starch. Bento;
kernel. : tract. iE

Per cent. | Per cent. | Per cent.| Per cent.| Per cent. | Per cent. | Per cent. | Per cent.
LGA haeemicich SRM SANE 4 100 1.8 4.10 12. 70 1. 80 79. 60 61. 90 3. 30
Milos eet 100 1. 89 3. 47 13. 99 1. 93 78. 72 68. 52 3.95
Peteritas. os Mees 100 1.79 3. 06 16. 69 2. 22 76. 24 64, 16 3. 38

In these comparisons the greatest differences are observed in the
protein and starch content. The other results show little variation.

In Tables 5, 6, 7, and 8 comparisons are made between the parts
of the corn and kafir kernel and the corresponding parts of the milo
and feterita kernel.

TABLE 5.—Comparison of corn hulls and kafir bran with milo and feterita brans.

Propor- Ether Crude }|Carboh

F F P y- Pento-

Material. wen of extract. Protein. fiber. drates. Starch. sans.
Per cent. . | Per cent. | Per cent. | Per cent.| Per cent.| Per cent.| Per cent.

Comhulls =e 5: 7.4 0. 79 0. 89 SH OGTR Se vane O4 36) 535 eS oc es ee ee

afin branes ss. 45 42 6.1 i 6. 80 4, 80 16. 20 GONZO Ee sernetate 18. 40

Mil ojbranee.sae. secee 5.5 i 4. 33 7. 08 15. 36 70. 16 60 OAT B55

4 1,
Feterita bran:-..-.... 6. 6 . 5. 74 6. 85 13. 56 70. 90 3. 89 15. 79

4 BULLETIN 1129, U. S. DEPARTMENT OF AGRICULTURE.

In studying these results it will be noted that the amount of ash
and ether extract in the corn hulls is decidedly lower than that in the:
bran of kafir, milo, or feterita. These determinations in the kafir,
milo, and feterita appear to resemble one another fairly closely.

TABLE 6.—Comparison of corn and kafir horny endosperm with milo and feterita horny

endosperm.
EEOBOr Ether C
: : tude |Carbohy- Pento-
Horny endosperm. Hon s f Ash. extract. | Proteim-| fiber. diates: Starch. a

Per cent.| Per cent. | Per cent. | Per cent. | Per cent. | Per cent. | Per cent. | Per cent.

Corn pty Scns? 50. 6 0. 44 1.15 ING CR) ||Soodoccnoe 80/563) fo ce ocecee| seeaeeea ee
Kafr ge) J) Sica a5. 48. 9 - 30 - 70 14. 50 0. 70 83. 80 68. 80 0. 70
Mill oes pee! o4. 7 - 06 15 15.11 69 83. 49 72. 24 . 69
Hoberitas- a een 2-8 61.1 SAL -33 19. 75 2.12 77. 09 60. 36 2.12

The most noticeable differences among these results are in the
comparatively high fat content of the corn and the comparatively
high protein content of feterita.

‘TABLE 7.—Comparison of corn and kafir starchy endosperm with milo and feterita starchy

' endosperm.
Propor-
F Ether . Crude | Carbohy- Pento-
Starchy endosperm. won G Ash. Sad Protein. Aor estes Starch. cl

Per cent.| Per cent.| Per cent.| Per cent.| Per cent. | Per cent.| Per cent. | Per cenit.

GORE ero cence: 22 25. 5 0. 26 0. 24 Ubek} | scdoeeeaac\e MICO bespecedodl lctacecoode
LGA i ea ee era oo Nene 35. 0 . 30 - 80 11. 66 0. 80 86. 44 70. 40 1. 90
Milos Set Sees 28. 7 6 (Al - 28 8. 91 - 81 89. 29 82. 50 4, 35
Heberitges-- Ssea- 54: 25. 1 - 96 . 64 10. 61 2. 38 85. 41 75. 84 4, 66

These results show a marked similarity, the protem content being
slightly higher in the kafir than in the other grains.

TABLE 8.—Comparison of the corn and kafir germ with the milo and feterita germ.

: Ether : Crude perboby Pento-
Germ. tion of Ash. etniee Protein. Aber fentes Starch. sence

Per cent. | Per ceni.| Per cent.| Per cent. | Per cent. | Per cent. | Per cent. | Per cent.
34. 84 19. 80

COLay ae SARIS ae eI a 5. 9.90 Po S484 AGS SO oo SS SONAR Pe eee ee ere
Kiahirs fei Se Aes 10. 0 13. 20 31. 50 19, 30 3. 80 32. 20 Le aye eee 6. 10
IMAL OSS i Ny SS WEES Se eo 9. 46 19, 92 20. 84 9.11 40. 67 1.53 8. 57
Heteritae . fee Lee: se 11. 35 25. 45 21. 70 8. 54 32. 96 2.16 6.95

In Table 8 notice is immediately taken of the low ether extract of
the milo germ. The other results show a great similarity.

A general consideration of all the tables shows that the protein
content of the feterita is higher than that of the other grains. The
horny endosperm in each case has more protein than the starchy
endosperm. The germs of these sorghums are very similar in com-
position.

MILO AND FETERITA KERNELS. 5
MALTING OF KAFIR, MILO, AND FETERITA.

While the work just reported was in progress the question of the
diastatic power of malts made from these sorghums arose. For some
time little attention has been paid to grains other than barley for
malting purposes, as this grain has served the brewing industry
satisfactorily. However, it was thought that a comparison of the
diastatic power of barley with that of the sorghums, kafir, milo, and
feterita might be of value.

MALTING PROCESS (5).

The grain was washed free from chaff, weed seeds, and other foreign
material, covered with clean, fresh water, and allowed to stand for
12 hours, the water being replaced once or twice during this period.
The water was then removed and the grain was allowed to stand for
an additional 12 hours. This entire operation was repeated for such
a time as was required to bring about complete steeping. The grain
was considered thoroughly steeped when it could be crushed between
the thumb and fingers and the inside was not hard or glassy, but soft
and chalklike.

SPROUTING.

After the water had been removed the steeped grain was allowed
to. germinate at a temperature of 15.5° C. In about six days the
sprouts which had been developing inside the seed coat forced their
way out at the end of the grain opposite the rootlet. The germi-
nation was continued for from 8 to 14 days, or until the sprouts were
about three or four times the length of the grain.

DRYING.

All moisture possible was expelled, at first at room temperature
and finally at 40° C. It was found especially advantageous to
observe the following precautions (4). To prevent molding as much
as possible, the grain after being washed and soaked for one hour in
water was allowed to stand for one-half hour in 0.24 per cent solution
of formaldehyde, after which the steeping in water already described
was continued. The grain was germinated between approximately
sterile damp towels to prevent molding and drying, the towels being
replaced every other day.

COMPARISON OF TEMPERATURE, TIME OF STEEPING, AND TIME OF GERMINATION OF
GRAIN SORGHUMS.

A comparison of the temperature, time of steeping, and time of
germination of the grain sorghums investigated is shown in Table 9.

6 BULLETIN 1129, U. S. DEPARTMENT OF AGRICULTURE.

TaBLE 9.—Com parison of temperature, time of steeping, and time of germination of
grain sorghums.

Average
aie daily
Time of | tempera-
Malt. see ermina-| ture
pe tion. during
germina
tion
Hours. Days. Ve:
NEG tO eae ART saan ee A Seles Noda ESP AAO ad hs lace IS Cech ae Aue lal ie 30 14 uZ/
Ins Kl Ko eee eR Nis ah ep et Agar pen MS al Nee a Cg Since aS ae a Gy I oP 30 8 20
WOGCLIGA Ss =o Ree oe hae oe wale ei elektro ee ee Ce ee secre 22 10 20

The difference in the time of steeping shown in Table 9 is due to
the capacity of the various grains to absorb water, this capacity
being governed principally by the hardness and compactness of the
grain. The interior starchy portion of the kafir and milo kernels is
harder and more glassy than that of the feterita, and consequently
requires a longer time for the complete absorption of water. The
time of germination varies in each case, but is governed to a large
extent by the temperature. The grain required a shorter time for
germination in cases where the temperature was higher.

DIASTATIC POWER OF MALTED GRAIN SORGHUMS.

After the malting was completed the finished malt was analyzed
by the following methods:

Preparation of sample.—After the malt had been thoroughly mixed
and a uniform sample taken, it was ground to pass a 20-mesh sieve.

Moisture.—Two grams of the ground malt was accurately weighed
in a covered weighing dish and dried at 60° C. in a vacuum to con-
stant weight.

Diastatic power (3).—Twenty-five grams of ground mae was
extracted with 500 cubic centimeters of distilled water (free from
ammonia, nitrates, etc.) for 3 hours at 21° C. and filtered. The first
100 cubic centimeters of the filtrate was rejected. Then 100 cubic
centimeters of a 2 per cent starch solution (soluble starch prepared
according to Lintner) was treated with 1 cubic centimeter of the
malt extract of diastase solution for 1 hour at 21° C., 50 cubic centi-
meters of Fehling solution was added, and the whole was heated
rapidly to 98°C. It was next placed in a boiling water bath for seven
minutes, and, without being diluted, the cuprous oxid was filtered
immediately, dried, and weighed. The weight of cuprous oxid was

calculated to copper by the following factor: ae Cu,0~°- 8882. The

weight of copper found minus the weight of copper reduced by 100
cubic centimeters of the 2 per cent starch solution (determined by a
blank on this amount carried through the regular procedure) was
divided by 0.441 (gram of copper in 50 cubic centimeters of Fehling
solution), and this result, multiplied by 100, gave the Lintner value.

MILO AND FETERITA KERNELS, 7

Acidity.— Fifty grams of ground malt was digested with 300 cubic
centimeters of distilled water at 15.5° C. for three hours. The
acidity of the filtered extract was measured by titrating against
N/20 sodium hydroxid and calculated to percentage of lactic acid.

A comparison of the diastatic power of some of the malted grain
sorghums with that of a barley is shown in Table 10.

TaBLE 10.—Comparison of the diastatic powers of barley, kafir, feterita, and milo malts.

: : Acidity as lactic
Diastatic power. cide
Malt. Moisture.

Moisture Dry Moisture Dry
basis. basis. basis. basis.

Per cent. | Degrees. | Degrees. | Per cent. | Per cent .
6.73 162. 4 174.1

aArleysce eee ues sl eS MRE RE Bo 2 PRD be Mee 0.176 0.189

ea L Tee ees mrp RU i AE LE Te 6. 88 9.5 10. 2 221 227
Betehitalwe beer ek By (co a ee ee .aeens, 92 35.0 BEG TA. Peal ee
FN coe oie ae ce eA eta le cee a see | 5.97 35.3 CUS | Mee ea tired eb NES

The sample of barley malt shown in Table 10 is of exceptionally
high diastatic power, being much higher in diastase than the ordinary
dried brewing malts, which range between 20° and 40° Lintner, and
therefore can not be taken as an average representative of that type.
From the standpoint of the brewer, the color, flavor, and percentage
of soluble material play a very important part, and the diastatic
power is sacrificed to some extent to bring about these factors through
the action of heat durmg drying. The grain sorghums shown in
Table 10 were malted under conditions that would give the highest
possible diastatic power, the other requirements of a good brewing
malt being sacrificed to obtain this property.

The acidity of the kafir malt was determined as a check on the
malting process for the purpose of showing that the acidity was not
high enough to have any effect upon the diastatic power.

The results obtained show conclusively that the sorghums investi-
gated do not meet the requirements of a green malt. The diastatic
power of these sorghums, with the exception of kafir, is comparable
with that of dried malts, when malted under conditions that would
give the highest possible diastatic power. When subjected to tem-
peratures that would give the color and flavor required in a dried
malt, however, this diastatic power would be too low for all practical
brewing purposes. |

SUMMARY.

On the whole, the kafir, corn, milo, and feterita resemble one
another in composition and appearance. The proximate constituents
of the kernels of these four sorghums indicate their value as food for
man and domestic animals, and show the possibility of their being
used as raw products in certain important commercial operations
having for their purpose the manufacture of starch, sirup, alcohol,

8 BULLETIN 1129, U. S. DEPARTMENT OF AGRICULTURE.

and oil, when proper machinery and processes have been devised.
It has been found, however, that it would probably be impracticable
to use them commercially for malting purposes.

BIBLIOGRAPHY.

(1) Brmwe tt, G. L. A physical and chemical study of the kafir
kernel. U.S. Dept. Agr. Bul. 634,6 pp. 1918.

(2) CHurcHILL, O. O., and Wricut, A. H. The grain sorghums.
Okla. Agr. Exp. Sta. Bul. 102,68 pp. 1914.

(3) SHermMaAN, H. C., Kenpatt, E. C., and Ciarx, E. D. Studies
on amylases. I. An examination of methods for the deter-
mination of diastatic power. Jn J. Am. Chem. Soc. (1910),
of: 10%:

(4) Stewart, Ropert, and STEPHENS, JoHN. The effect of formalin
on the vitality of seed grain. Utah Agr. Exp. Sta. Bul. 108,
10 pp. 1910.

(5) Wente, A. O., and Totman, L. M. Potato culls as a source of
industrial alcohol. U.S. Dept. Agr. Farmers’ Bul. 410, p.
19-23." F910.

This bulletin is a contribution from—

ERUECHIE Of CRCMASIFIE = ee AS. tea WALTER G. CAMPBELL, Acting Chief.
Miscellaneous Division......-..--------- J. K. Haywoop, Chief.

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