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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
Water was added t o unpolished, uncooked rice, and small amounts of this material were sterilized in Erlenmeyer flasks. Strain A from silage, strain C from red rice, and strains D and E isolated from cheeses, were used. The silage organism gave a pink color t o rice grains, and caused some of the grains t o split into small portions, while others could be crumbled into smaller, hard particles. Strains C and D produced very deep, almost red-black color throughout the rice, but they broke down the grains so completely t h a t the mass became slushy. I n the belief t h a t the softening might proceed still further with no definite results, the reddened rice grains were spread out on a paper and dried. On drying they became a brilliant t o black-red, crumpled and shrunken, with grains adhering in small masses, and tough in texture. The mold discoloration penetrated almost completely. The use of strain E , also from Chinese soy cheese, resulted in more promising material. After being dried out from a somewhat slushy consistency, each grain of rice stood intact, although not plump or regularly defined. The superficial deep red layers crumbled in what was considered the approved' fashion, but below these the rice was hard and pinkish as in the case of strain A. The material, however, was considered worthy of exhibition. These laboratory products were compared with a sample of red rice collected in China by Dr. Yamei Kin, of the Bureau of Chemistry. I n this typical sample each rice grain is a regular, clear-cut particle, of a deep but dull carmine color. On rubbing between the fingers, these red rice grains crumble into a tissue-like envelop formed by the exterior surface of the grain, and a very fine, soft red powder, the particles of which go into suspension in water and into solution in ethyl alcohol or chloroform as well as in other solvents. A second experiment was laid out with exactness, replacing the rough, preliminary methods. Uncoated and unpolished rice was sterilized in Erlenmeyer flasks. After cooling, 2 5 per cent additional sterile water was added t o some samples and 3 0 per cent additional sterile water t o others. The results obtained with strains A, C, and D are worthy of note. On rice t o which 2 5 per cent of water was added, strain A grew with a most delicate rosy color, and caused a somewhat more complete disintegration of the rice grains t h a n in the preliminary experiment. It did not grow a t all on the rice t o which 30 per cent of water was added. It is evident, then, t h a t less than 2 j per cent of water should be added t o obtain red rice. Strain C produced a dull, orangered color on rice t o which the 2 j per cent of water had been added. The grains adhered occasionally, and when a n attempt was made t o crush them they merely split into smaller hard portions. The same results were obtained when 30 per cent additional water was used, except t h a t a rather noticeable amount of close, felty mycelium, cementing the grains together, was obtained. It is believed t h a t too much water is a n inhibiting factor here. On rice to which 2 5 per cent
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of water was added, strain D actually produced reddened rice kernels, which may without hesitation be called American-made Chinese ang-khak. The rice kernels, which were well shaped, each intact in itself, and of a rich carmine-red, crumbled t o powder between the fingers, and the outer layers resembled a tissue-like coating. Thirty per cent additional water caused this strain t o act like strain C, the material, however, being tougher, more floccose, and entirely unsatisfactory. Evidently rice which contains an addition of 25 per cent of water, when held a t room temperature (22-24' C.), is a t a critical point, so far as the various strains of Monascus purPureus Went are concerned. This fungus, although employed commercially only in the Orient, is more cosmopolitan in its habits t h a n its applied use would indicate. Apparently, Monascus purpureus Went is a specific name applicable t o a. group of strains having a rather consistent morphology, but varying greatly in their quantitative production of the same substances. SUMMARY
I-The characteristics of red rice, a common Chinese vegetable color used in food products, are due t o a mold. 11-This mold, known as Molzascus purpureus Went, although apparently found outside the Orient, is utilized in this way only in China. 111-All strains of Molzascus purpureus are not adapted t o the production of red rice, since each varies quantitatively in its physiological activity. Only those strains which produce a rich dark red growth throughout rice with a water content low enough to permit well-appearing grains in the finished product are acceptable for this purpose. THE EFFECT OF MOLD UPON THE 0J.L IN CORN By Frank Rabak BUREAUOB PLANTINDUSTRY,U. S. DEPARTMENT OP AGRICULTURE, WASHINOTON,D. C. Received July 23, 1919
Under certain conditions of storage, corn ,undergoes spoilage induced largely by a n excess of moisture a n d usually manifested by a moldy appearance. A common mold which attacks corn under these conditions is Penicillium, the growth of which necessarily causes deterioration, the extent and nature of which depends upon the length of the growing period of the mold and the particular constituents of the corn which are subject t o decomposition. From the general appearance of corn attacked by this mold i t is evident t h a t changes are taking place in the grain and i t was for the purpose of studying the effect of the mold upon the f a t t y oil in the corn t h a t this investigation was undertaken. I t is natural t o assume t h a t as the time period during which the mold is allowed t o grow, increases, certain constituents of the corn are contributing t o t h e growth and are therefore undergoing change, while certain other compounds are possibly being metabolized by the mold. The fatty oil belonging t o
Jan., 1920
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TABLE I-DESCRIPTION, TIMEOF SPOILING, PERCENTAGE OF MOISTUREAND OF OIL IN CORNSAMPLES, AND PHYSICALPROPERTIES OF THE OILS Time of MoisSpoilture ing Per .SAMPLE CONDITION Days cent 1 Market sample, fair . 21.9 condition. Kernels yellow in color 2 Most of corn affected 17 18.2 with mold. Kernels gray and dirty. Musty odor 3 Whole mass of corn 34 20.1 affected with mold. Dirty gray in color Intense moldy odor
.
4
5
Dirty gray mass with strong musty odor. Yellow color of kernels gone Dirty gray, moldy, solid mass, with strong, offensive odor
55
90
21.62
17.0
Oil (Calculated on Dry Weight) Per cent 5.58 4.33
2.67
2.06
2.02
-
-- PHYSICALPROPERTIESOF
THE
FIXED OIL-
Color Pale brownish red
Odor Mild, fatty
Pale brownish red. Some solid matter separated on stand1ng Brownishred. Darker than Nos. 1 and 2. Considerable yellowish solid matter separated on standing Very dark brown. Much solid separated on standing
Strong, fatty, slightly acid
Taste Bland, fatty, becoming slightly bitter Fatty, becoming bitter
Strong, musty. Disagreeable, sour
Fatty, bitter
Disagreeable, strong, sour, musty
Strongly bitter
Dark, reddish brown, almost black. Large portion of oil became semi-solid
Intensely strong, disagreeable, sour, musty
Strongly moldy
the former class of substances forms the basis of this paper, in which are discussed the general changes which take place in its content and composition. Under favorable conditions the fatty oil contained in the germ of the corn readily becomes rancid, as do other oils under the same conditions. The development of rancidity is accompanied by more or less severe changes in the composition of the oil, which is evidenced by a noticeable difference in its taste and odor due t o the formation of certain compounds of acid, aldehydic, or ketonic character. The prime object of this work was t o study what changes, if any, take place in corn oil due t o the growth of Penicillium on the corn. A small part of a market sample of corn, presumably in the condition in which i t is ground into meal, was taken for oil determination, and the remainder was placed in a large stone jar and inoculated with the mold Penicillium and set aside. After a short period a second sample of the corn was taken for analysis and the remainder again set aside. This sampling was continued a t intervals for a period of go days, four samples of the spoiled corn being obtained in all. Determinations were then made of the moisture and oil content of each sample. Physical constants and chemical examination of the mixed acids (insoluble acids), liquid and solid acids of each oil were also determined in order t o enable comparisons t o be made. All determinations were made according t o the methods prescribed by the Association of Official Agricultural Chemists.l For the purpose of comparison the several samplestaken were described as t o condition, general appearance, and time of spoiling. The percentage of moisture and of oil in the corn samples, and the physical properties of the oils, including color, odor, taste, specific gravity and refraction, were added t o the data and are given in Table I. It will be observed from Table I t h a t as the mold progressed in growth the original yellow color of the corn kernels was gradually displaced by a dirty gray until the whole developed into a solid mass, while the musty or moldy odor gradually became more offensive. The percentage of moisture fluctuated slightly 1 H. W. Wiley, "Official and Provisional Methods of Analysis," J. Assoc. Official Agr. Chemists, U. S. Dept. of Agr., Bureau of Chemistry, Bulltiin 107 (Rev.).
strongly
bitter,
Specific RefracGravity tion 0.9204 1.4712 (23' C.) (23' C. 0.9228 (23'C.)
1.4722 (23' C.)
0.9212 (23OC.)
1.4725 (23' C . )
0.9307 (24' C . )
(24' C.)
0.9444 (24' C )
(24' C.)
1,4780
1,4800
during the first j 5 days, dropping t o the lowest point a t the end of 90 days, when the mass of corn kernels was hardly recognizable. A constant decrease was noted in the oil content of the samples, from 5.58 per cent in the market sample t o 2 . 0 2 per cent in the thoroughly decomposed sample. Likewise the color of the oil became progressively darker with an increased amount of solid matter separating. The odor of the oil from Sample I , which was mild and fatty, developed into a very strong, musty, and disagreeable odor, while the taste gradually became very bitter and moldy. The first indication of any noteworthy change in the composition of the oils is displayed in the specific gravities and indices of refraction, both of these physical constants increasing in magnitude as spoiling developed. CHEMICAL EXAMINATION O F CORN OIL SAMPLES
I n order t o show the changes in the oils as observed from the examination of the physical properties, a careful analysis of each sample was made with respect t o acid, saponification and iodine values, and the percentage of volatile acids (Reichert- Meissl value), soluble acids, insoluble acids, acetyl value and unsaponifiable matter (Table 11). TABLE 11-CHEMICAL PROPERTIESOF OILS FROM CORNSAMPLFS Soluble InsolAcids uble (Calcu- Acids lated (Hehncr Volatile as Bu- NumUnsaponSaponiAcids tyric) ber) ifiable OIL Acid fication Iodine (Reichert- Per Per Acetyl Per SAMPLE Value Value Value Meissl) cent cent Value cent 1 13.6 190.3 121.0 12.8 1.3 93.6 15.3 4.13 2 46.7 191.7 121.3 2.95 1.5 90.5 10.6 9.9 3 84.6 192.4 120.4 2.23 3.28 92.3 61.1 10.8 4 68.7 185.1 119.9 2.92 2.35 91.7 28.4 15.3 5 72.1 126.6 9 6 . 6 Insuffi- 4.05 . . . . 6 8 . 4 25.4 cient oil
The acidity of the oil samples shows a general increase of considerable magnitude. Sample I exhibits a rather high acid value which is probably accounted for by the fact t h a t the market sample was only fair in condition and contained a high percentage of moisture, which was more or less conducive t o spoilage. After the first sampling the acid value of the oil had increased more t h a n threefold. The highest acid value was found in Sample 3 a t the end of 3 4 days of spoilage, followed by slight diminution in Samples 4 and 5 a t the end of 55 days and go days, respectively.
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TABLE 111-PHYSICAL AND CHEMICALPROPERTIES OF MIXSD ACIDS (INSOLUBLE ACIDS) OF OILS FROM CORNSAMPLES OIL
SAMPLE COLOR 1
Light yellowish brown
ODOR Fatty
TASTE Bland, fatty
2
Brownish red
Fatty, not agreeable
F a t t y , bland, becoming bitter
3
Reddish brown
Fatty, disagreeable, musty
4
Brown
Disagreeable, fatty, rancid
F a t t y , becoming bitter and unpleasant Very bitter, f a t t y
5
Dark brown
Rancid (semi-solid)
Disagreeable, bitter
TABLEIV-PHYSICAL OIL Yield SAMPLEPer cent COLOR 1 84.4 Light reddish brown 2 3 4 5
80.0 79.5 82.7
....
ODOR Mild, fatty
TABLSV-PHYSICAL Yield Per cent 11.1 10.3 12.6 9.09
SAMPLE I . . . . ................... 2 3 4 5
.......................
....................... ....................... ...........................
....
Refraction 1.4659 (220 C.) 1.4653 (23' C.) 1.4672 (24' C.) 1.4700 (23' C.)
Neutralization Value 184.8
....
Iodine Value 129.1
183.2
142.2
188.8
126.6
186.5
122.9
114.8
...
CHEMICALPROPERTIES OF LIQUID ACIDS OF OILS Specific Neutralization TASTS Gravity Refraction Value F a t t y , slightly acid, becoming 0.9105 (22' C.) 1.4674 (22" C.) 184.4 bitter F a t t v , becoming bitter 0.9087 (23'C. 1.4670 23OC.1 185.8 F a t t y , bitter 0.9110 (24" C. 1.4665 124' C.) 175.3 Fatty, becoming bitter 1.4730 (23OC.) 171.7 0.9194 (23'C.
AND
Brownish red F a t t y bland Dark brown Faint,' fatty Dark brown Unpleasant, fatty Insufficient oil for separation of liquid acids
OIL
Specific Gravity 0.9038 (220 C.) 0.9055 (23O C.) 0.907 1 (24' C.) 0.9169 (23' C.)
AND
1
Iodine Value 146.5 153.0 135.3 132.8
CHEMICALPROPERTIESOF SOLIDACIDS OF OILS
APPEARANCE ODOR Pale yellow, tallow-like None Pale yellow, waxy None Pale yellow, waxy None Darker yellow None Insufficient oil t o make separation of solid acids
In saponification values the same general increase is noted in Samples I , 2 , and 3, followed by a decrease in Sample 4 and a sharp decline in Sample 5 , indicating a consumption or decomposition of the glycerides a t this point. The iodine values remain almost constant in the first three samples, with a decided decrease in Samples 4 and 5 , indicating a lowering of t h e content of unsaturated acids. The high percentage of volatile acids in the original oil and the extremely sharp decrease, remaining almost constant, in the remaining oils points t o the possible decomposition of these constituents by the mold as rapidly as formed. The formation of soluble acids apparently was assisted by the gradual spoilage of the corn. The formation of insoluble acids, on the other hand, appears t o have been retarded slightly after the molding began, The acetyl value, which is a measure of the hydroxylated glycerides, exhibits noteworthy fluctuations, being especially high in Samples 3 , 4) and 5 , showing a rapid formation of these constituents as the experiment progressed. One of the most remarkable changes brought about by the growth of the mold was the formation of unsaponifiable substances in t h e oils, a steady increase t o 25.4 per cent having been found. I t is very probable t h a t the solid matter mentioned in the discussion of Table I, and which was observed increasing in each sample of oil, consisted largely of unsaponifiable substances elaborated from the oil by the mold.
LIQUID AND SOLID ACIDS O F OILS
A separation of the liquid and solid acids was made from the insoluble acids by methods prescribed by t h e Association of Official Agricultural Chemists. The physical and chemical properties of the liquid acids were determined (Tables IV and V).
Melting Point Deg. C. 55-58 55-56 52-55 53-56
Neutralization Value 207.9
208.4 214.2
...
The yields of liquid acids are shown t o fluctuate considerably, a lower yield being indicated in oil from the moldy corn. The color, odor, and taste are also more pronounced in the moldy samples. A slight increase is observed in the specific gravity and refraction of the most moldy samples. The neutralization values and also t h e iodine values of these same samples are noticeably lower t h a n the acids from less spoiled samples, indicating a decomposition of these acids during spoilage. The yields of solid acids from the respective oils likewise differ, a perceptible drop being observed in Sample 4. The melting points also fluctuate. Neutralization values show slight increase as the spoilage continued, showing t h a t a material effect was being produced even on the solid acids of the oils. CONCLUSIONS
It may be stated t h a t the effect of the spoilage of corn from the growth of mold was noticeably manifested in connection with t h e f a t t y oil. A consumption of oil by the mold was apparent, as manifested by the decrease in the yield of oil a t each stage of decomposition. As regards composition of the oil, spoilage of the corn caused very decided increase in the free acids, the soluble acids, hydroxylated acids (acetyl value), and unsaponifiable constituents, with a decrease in the percentage of volatile acids, insoluble acids and unsaturated acids. INSOLUBLE SOLIDS IN JAMS, PRESERVES, AND MARMALADES By C. A. Clemens
I N S O L U B L E ACIDS O F OILS F R O M CORN SAMPLES
The insoluble acids (mixed acids) obtained from each sample of oil were subjected t o physical and chemical examination (Table 111.)
TASTE Tallow-like Tallow-like Tallow-like Tallow-like
SOUTH DAKOTA FOOD AND DRUGDEPARTMENT, VERMILION, S. D . Received August 9, 1919
The official method for the determination of insoluble solids in fruit products' is slow and cumbersome. A method has been worked out which is rapid, easily manipulated, and a t the same time obviously offers greater accuracy. By the substitution' of a n alundum crucible for a linen filter i t becomes possible t o apply suction and a t the same time t o have a better filter1
J . Assoc. O f i c i a l Agr. Chemists,[2] 2, 177.
