MILK Effect of Different Sources of Radiant Energy on Flavor and Antirachitic Potency flavor is produced, the resultant antirachitic quality is greatly dissimilar. A n analysis of the emission of the various arcs, in so far as the data are available, permits the conclusion that energy ranging in wave lengths from 2600 to 3100 A. is less active in flavor production than energy of wave length less than 2600 A. A similar analysis of the radiation of the spectral region 3100 to 7000 A. indicates that radiations of 3100 to 3800 A. are more active in producing flavor than those of wave length 3800 to 7000 A.
When radiant energy from carbon arcs
and quartz mercury vapor arcs is used for the antirachitic activation of milk, definite changes in flavor are produced with excessive exposure. The effect is due to radiations from that part of the spectrum which is known to have an antirachitic effect as well as to parts of the spectrum devoid of such properties. When radiant energy as filtered through quartz from these sources is used to irradiate milk until a uniform intensity of
HE commercial irradiation of milk is essen-
may be called Liburnt,”“burnt protein,” “burnt feather,” or “mushroom” flavor. This flavor is to be definitely distially a process whereby milk is exposed to tinguished from the so-called papery, cardboard, or cappy radiant energy of a certain quality and flavors, which may result from the action of radiant energy or intensity to increase its antirachitic potency. For the inducmetals on the lipids or fats in milk. The flavor under intion of this, antirachitic activity, ultraviolet radiations, acd vestigation may be spoken of as an “activated flavor” and is specifically those ranging in wave length from 2300 to 3130 A., to be definitely distinguished from an ozone flavor. The are essential. Within this range, except for the upper limits, latter is particularly nauseating. The activated flavor has it is apparently immaterial from the standpoint of efficiency been found to be definitely associated with the protein fracwhich wave lengths are used ( 3 ) . Unfortunately, however, tion of milk (6). It may be distinguished from other flavors it is impossible to produce the desirable radiations without by the action of heat, which tends to intensify it when the generating ultraviolet of longer wave length as well as visible milk is brought to the boiling point for a few minutes and light; nor can these radiations of longer wave length be subsequently cooled. eliminated eficiently by use of screens. Such screens as might be used are usually too absorbent for the radiations of shorter wave length as well. Irradiation Experiments Light energy, under certain conditions, will cause the deThe experiments reported deal specifically with an attempt velopment of an unnatural flavor in milk. Hammer and to determine what part of the spectrum of the various availCordes (4) and Tracy and Ruehe (6) reported that flavor able sources of ultraviolet are particularly instrumental in the defects were obtained in milk exposed under varying conditions, to sunshine. The irradiation of milk, as commercially production of an activated flavor. The use of different parts of the spectrum as obtained from a Bausch and Lomb prism practiced, involves the use of the total emission (ultraviolet, monochromater and a water-cooled constricted quartz mervisible, and infrared) from various sources. Improper or uncury-vapor arc failed to provide sufficient intensity for decontrolled application of the process may result in the dev e l o p m e n t of the flavor. and the velopment of a flavor defect in milk K. G. WECKEL, H. C. JACKSON, use of special filters proved difficult whiih may interfere with consumer acR. HAMAN, AND H. STEENBOCK because for the most part they do ceptance of the product, however denot function with a high degree of sirable nutritionally. The acceptance University of Wisconsin, Madison, Wie. of the process of pasteurization was s e l e c t i v i t y . The direct radiation retarded for some t i m e following its introduction partly because of the presence of a “heated” flavor. The perfection of the pasteurization process served to reduce, if not prevent, the undesirable flavor effects. A study was therefore undertaken to determine what factors were involved in causing the development of a flavor defect when milk is irradiated under certain conditions for the purpose of increasing its antirachitic properties. The flavor defect may be described best as a “flat” flavor in its incipient stage, gradually changing with continued exposure into what
of v a r i o u s a r c s w a s t h e r e f o r e utilized in most of the experiments. Three sources of radiant energy were used for irradiation of the milk-viz., the carbon arc, the quartz mercury-vapor arc, and the cold-quartz arc. Five types of carbon electrodes, the C, B, U, Magnesium, and Sunshine (National Carbon Company), were employed. The quantitative emission from the carbon arcs was determined from the emission curves presented in Figure 1 ( 2 ) . These curves reveal important differences in the relative emission of the arcs in the zone 2300653
VOL. 28, NO. 6
INDUSTRIAL AND ENGINEERING CHEMISTRY
63 4
test technic. The Steenbock and Black ration 2965 was fed rats 21 to 25 days old until rachitic; the milk supplement was then given for 7 days, and the calcium deposits determined on the tenth day.
Flavor Formation
’f
2500
3SOO
An&sfrom
I 4500
I
u Corbon
I
8 Corbon
I
I 5500
I
The activated flavor was induced in milk when sufficiently irradiated through either quartz or glass. The flavor in either case was the same, or at least similar. The short-wave transmission limit of quaztz is approximately 2000 d., and of the glass used here 3100 A. Visible and infrared radiation as obtained from a Burdick Roalite Infra Red lamp did not produce a similar flavor effect. It may be assumed tohat the lower limit of radiation of the infrared lamp is 7000 A. The change in flavor, therefore, may be assumed to be due to radiations of this wave length or less. TABLEI. EFFECTS OF VARIOUS TYPES OF RADIATION ON FLAVOR
I
-Minutes Requiredto Produce Flavor
6500
Unifs
Through
FIGURE1. COMPARISON O F SPECTRAL DIBTRIBUTION CURVESOF CARBONARCS (35 VOLTS,25 AMPERES) 2600,2600-3100, and 3100-7000 A. For the zone 2300-3100 h;. the emission of the U carbon arc operating at 35 volts and 25 amperes was 4922 ergs per sq. cm. per second, the C carbon 3692, the B carbon 2872, the Magnesium carbon 2444, and the Sunshine carbon 788. Available data on the energy distributi2n of the various arcs were limited to the region 2300-7000 A. The effects of Tadiation outside this range, especially of those less than 2300 A., were assumed as being due to energy within the range 2300-7000 h;. The emission of the Hanovia mercury-vapor arc is distributed in various lines on a faint continuous spectrum. The intensity of these lines diffezs tremendously (1). The energy for the region 2300-.3$60 A., inclusive, is principally 6.88; distributed as f o l l o ~ s ;2480 A, 1.58 ger cent; 2537 2650 8., 7.26; 2803 A., 2.40; 2967 A., 3.61; 3025 A,, 25.5; 3130 h;., 23.36; 3341 8.,3.44; and 3660 A,, 34.41 per cent. Approximately 90 per cent of the emission of the colGquartz mercury arc is radiated in a limited zone at 2530 A. Detailed differential analyses of the emission of the coldquartz arc were not made.
&.,
In all experiments the milk was irradiated in 50-cc. quantities The inside measure of the cells was 10.5 cm. square, approximately 1 cm. deep. One face of the cells was cut away to allow the insertion of a pane of quartz or glass, 12.0 cm. square. The cells were placed 50 and 85 cm. from the carbon arc and quartz arcs, respectively. During exposure the milk was agitated continuously by rotating the cell on its short axis by means of a motor and with its face exposed continuously to the source of light. Churning of fat in the cells was avoided by use of homogenized milk, previously heated to prevent lipolytic activity. The use of filters in the cells was restricted to that of window glass 1.5 mm. thick, and of quartz, 2.0 mm. thick. The transmission properties of the filters was determined by means of a Hilger quartz spectroscope employing a sector photometer and hydrogen discharge tube, The milk was exposed to the radiant energy from the respective arcs until a slight but definitely perceptible flavor was obtained. The presence of such an intensity of flavor was arbitrarily designated as a “unit” of flavor. The uantity of radiant energy of given quality to which the milk ha! been exposed when the unit of flavor was produced was calculated from the emission curves of the respect,ivearcs. The results were expressed as ergs per cc. of milk. Determinations of the antirachitic potency of the milk possessing a unit, of flavor were made by the Johns Hopkins line
Throunh
quartl. glassEnergy Source (2300(3100(Aro) 7000 d.) 7000 A.) U carbon 11 60 C carbon 12 90 B carbon 13 75 Mctenesium cirbon 30 120 Sunshine .- ~ .
-Calculated Source ofActivated Flavor, Units Produced
By emiaBy emisBy.tota1 sion in B ~ O Uin emission 2300-3100 3100-7000 (2300-7000 4. 4. A*, Region Region 1.0 0.816 0.184 1.0 0.867 0.133 1.0 0.827 0.173 1.0
0.75
0.25
0.571 0.965 0,929
0.429 0.035 0.071
~ ~ . ~ ~ .
carbon 30 70 1.0 26 Cold-quartz 7200 1.0 10.5 Mercury-vapor 150 1.0 a Flavor not evident even after thia period.
The comparison was made of the rate of flavor formation in milk when irradiated either through quartz or glass by the emission of the various arcs. When irradiated through quartz, the effect was the result of the action of the sum tot$ of the emission from the lower limits of approximately 2300 A. to the upper limits. When irradiated through glass the effect was due to the radiation with a minimum wave length of 3100 A. and a maximum wave length approximately the same as for quartz. By the differential effect, using the two filters, i t was possible to determine the relative effectiveness of the energy ranging in wave length from 2300 8.t: 3100 A., and the radiations ranging in wave length from 3100 A. to 7000 8.
in brass cells heavily coated with block tin.
I
-
Rodufibn fmrn,&,&on 2600 -3/00A.
n
I
4L OF COMPUTED RADIATION NECESSARY FIGURE2. COMPARISON TO PRODUCE UNIFORM CHANGEIN FLAVOROF MILK FROM VARIOUS ARCSI N THE REQION 2300-3100 A.
JUNE, 1936
INDUSTRIAL AND EXGINEERING CHEMISTRY
The results of the rates of flavor formation in milk are presented in Table I. The data show that a marked difference occurs between the various sources of radiant energy in the time necessary to produce the flavor when the energy is transmitted first through quartz and then glass. For example, with the U carbon arc, 11 and 60 minutes were required to produce the flavor through quartz and glass, respectively, whereas by the use of the mercury vapor arc, 10.5 and 150 minutes were required. Another interesting comparison is found where, by the use of the Magnesium carbon arc, 30 and 120 minutes were required to produce the flavor through quartz and glass, respectively, whereas by the use of the Sunshine carbon arc, 30 and 70 minutes were required. The data in Table I show that in every case a relatively greater part of the flavor is produced by the action of radiation of wave lengths less than 3100 A., and that, therefore, energy of this quality as obtained from the arcs is relatively more potent in bringing about the flavor. Thus, when the cold-quartz and mercury-vapor arcs are used, 96.5 and 92.9 per cent, respectively, of the total flavor produced by the total emission of the arcs is brought about by the action of radiation of wave lengths less than 3100 A. When the Magnesium and Sunshine carbon arcs are used, the percentage figures are, respectively, 75.0 and 57.1.
655
_ _ _ _ _ ~
Source ss OFU Raa’ianfC €nerdy MG (ARC)8
-
3
T‘ ’s d
-
b
3 lu
Rodidon from R e e n 3800 - 70008..
4-
2-
-
-
FIGURE 3. COMPARISON OF RADIATION NECESSARY TO PROUNIFORMCHANQE IN FLAVOR OF MILK FROM VARIOUS ARCS w THE WAVE-LENGTH REQION TRANSMITTED THROUGH GLASS DUCE
The data in Table I1 show further that, if radiation only in TABLE 11. COMPARISON OF RADIATION FROM VARIOUSSOURCES the region 2300-3100 1.as obtained from the various arcs is NECESSARY TO PRODUCE UNIFORM FLAVOR CH.4NGE used to produce a unit intensity of activated flavor, the Units of Flavor estimated radiation required ranges from 5,493,000 ergs for Radiation ReProduced b y uired t o ProRadiation of Rethe Sunshine carbon to 12,756,000 for the Magnesium carbon Radiation (23001 uce Uniform Change in Flavor arcs. The magnitude of these differences suggests that cer3100 A.) Expended When Emission When Change in tain parts of the spectral region are more active in producing Is Limited t o ReFlavor Is Produced Energy Source (Arc)
U carbon C carbon B carbon Magnesium carbon Sunshine carbon Cold-quartz Mercuryvapor
by Total Radiation of Arc Ergs/cc. milk 7,146,000 5,848,000 4,928,000
gion 2300-3100
(Table I )
A.
0.816 0.867 0.827
Ergs/cc. mal k 8,758,000 6,753,000 5,966,000
9,567,000
0.750
12,756,000
3,120,000
...
0.571 0.965
5,493,000
10,458,000
0.929
11,270,000
...
TABLE 111. COMPARISON OF ANTIRACHITICACTIVITY OF MILK EXPOSED TO TOTtlL RADIATIOX FROM VARIOUS ARCS Source of Radiant Energy Assay (Arc)
Level a t Which Milk Was Fed Intern. units/qt.b 198
Sunshine carbon
4
hZ-5
Sunshine carbon
4
’564
11-3
B carbon
4
264
M-2
Antirachitic Potency When milk is subjected to the radiation transniittecl through quartz, as obtained from one of the several arcs, until a unit intensity of activated flavor is discerned, theoamount of antirachitic energy of wave lengths less than 3100 A. which is imparted will depend in part upon the relative amounts of flavor produced by the radiation in the zones from 2300-3100 and 3100-7000 A. A comparison was made of the relative amounts of such radiation imparted to milk when irradiated under the previously described conditions until a uniform intensity of activated flavor was obtained. The results of the expeiiments presented in Table I, in correlation with the radiation of the zone 2300-3100 A. as calculated from the spectral distribution curves of the various arcs reveals, as shown in Table 11, significant differences in the suitability of the arcs for the purpose of irradiating milk. For examgle, the estimated radiation limited to the region 2300-3100 A. and expressed as ergs per cc., which is applied to the milk when the unit flavor is obtained, ranges from 3,120,000 for the Sunshine carbon to 10,458,000 for the mercury-vapor arcs. The antirachitic quality of the milks thus irradiated follows a like order as determined by the bioassays; the results are summarized in Table 111.
No. of Animalsa
Calcium Deposition 2 narrow continuous line
1narrow t o mediumline 1 medium t o wide line
1 wide rachitic metaphysis 1 calcification on sidee 1 narrow broken line 1 medium metaphysis 1 specks 1narrow continuous line 1narrow t o medium line
1 medium line
M-1
C carbon
5
264
M-4
Magnesium carbon
4
264
M-7
C carbon
4
280
3 narrow line 1 narrow to medium line
M-8
Magnesium carbon
4
280
4 medium line
11-12
Mercuryvapor
7
330
2 narrow broken line 2 narrow line 3 narrow t o medium line
M-16
Magnesium carbon
4
330
2 narrow continuous line 1 narrow t o medium line 1 medium line
M-7
C carbon
5
561
5 wide rachitic m e t a p h y ~ i s
M-8
Magnesium carbon
4
561
3 narrow continuous line 2 medium line 1 medium line
1narrow metaphysis 2 wide line
1 wide rachitic metaphyais 1narrow broken line 2 narrow line a Includes only those animals having satisfactory food consumption and gain in weight. b T h e factor 3.3 was used t o convert Steenbock units t o International units.
456
VOL. 28, NO. 6
INDUSTRIAL AND ENGINEERING CHEMISTRY
.
flavor than others. The plausibility of this suggestion is brought out by the data presented in Figure 2. When the different arcs are compared by computing the radiation of the region 2300-3100 8. that would be required to develop a unit degree of activated flavor in milk, it becomes evident that substantially the same radiation of the region less than 2600 d. is involved for all the arcs studied, whereas the radiation of the region 2600-3100 8. is extremely variable. In order to keep the activated flavor to a minimum in the antirachitic activation of milk by irradiation, it would, therefore, seem advisable either to screen out radiation of short wave length or to select a source of radiant energy which has a low emission within the region less than 260: A. as compared with the emission in the region 2600-3100 A. A study similar to that described was made of flavor produstion by radiations of wave lengths greater than 3100 A. Experimentally the radiations from the various arcs filtered through glass were allowed to act until a uniform unit intensity of flavor had been produced. By means of the relationship between the time of exposure and the intensity of the radiation, an estimation of the radiation expended was made
as has been described. The data in Figure 3 show that, with all arcs, approximqtely the same amount of energy from the region 31OC-3800 A. had beeon used, whereas the amounts of radiation from 3800-7000 A. varied considerably. Therefore, the conclusion appears justified that radiations ranging in wave length from 3100-3800 d. are more responsible for production of flavor than those of 3800-7000 d.
Literature Cited (1) Anderson, W. T., Jr., emission curves and data, Newark, Hanovia Chemical and Mfg. Co., 1934. (2) Downes, C. A., emission curves and data, Cleveland, National Carbon Co., 1934.
(3) Haman, R. W., and Steenbock, H., Ann. Rept. Wis. Agr. Expt. Sta., Bull. 428 (1934). (4) Hammer, B. W., and Cordes, W . A., Iowa Research Bull. 64 (1920). (6) Tracy, P. H., and Ruehe, H. A., J.Dairy Xci., 14,250 (1931). (6) Weckel, K. G., and Jackson, H. C., Ann. Rept. for 1936, Wis. Am. Expt. Sta., 1936. RECEIVED February 24, 1936. Published with the permission of the Director, Wisconsin Agricultural Experiment Station.
Age Resisters in Vulcanized Rubber Hydroxy-Substituted
N-Phenyl Morpholines N THE general study of age resisters for rubber and other commercial materials, a number of hydroxy-substituted N-phenyl morpholines were prepared and tested. It was found that certain of the hydroxy-substituted N-phenyl morpholines are excellent age resisters (S), of activity comparable to that of phenyl-p-naphthylamine but with less staining in lightcolored compositions. The structure of the morpholines is probably not well known; therefore, the following structural formulas will suffice to describe these new compounds: Hz 4 0 1 - h l c 3 2
\c----d
HZ
C
In general, the new compounds referred t o in the paper are readily prepared by treating the proper aryl amine with 8, /3'-dichlorodiethyl ether in the presence of water and calcium carbonate at 100' C., with violent agitation.
Aging Tests To illustrate the effectiveness of hydroxy-substituted N phenyl morpholines compared with phenyl-&naphthylamine 2
and the unprotected control, physical tests of artificially aged rubber stocks are listed in Table I. The basic stock is a carbon black tread of low quality, ohosen so that the effectiveness of an antioxidant would be apparent on the physical tests. The general recipe is as follows: Rubber. smokedsheets No. 1 Sulfur .' Zinc oxide Carbon black
52.46 3.01 15.06
20.09
Palm oil Mineral rubber Hexamethylene tetramine Age resister
3.01
6.02 1.36
0.50 100.50
The oven-aging (2) consisted of exposing standard dumbbell test strips in a current of air at 70" C. for the period speci-
B
Hz H2 Phenyl morpholine or 4phenyltetrahydro-l,4-oxazine
1
ARTHUR W. CAMPBELL1 A N D MARION C. REED2 B. F. Goodrich Company, Akron, Ohio
Present address, Thermatomic Carbon Company, Terre Haute, Ind. Present address, National Carbon Company, Cleveland, Ohio.
The hydroxy-substituted N-phenyl morpholines as a class are age resisters in vulcanized rubber. I t is indicated that the hydroxyl group is most effective as an age resister when present in the 4- or para position. The position of the hydroxyl group or hydrocarbon radical in the molecule is important, the 2-methyl4-hydroxy-N-phenyl morpholine causing the least staining. A hydrocarbon radical in the 3-position increases solubility in rubber.
