INDUSTRIAL AND ENGINEERING CHEMISTRY
574
lines, and to W. J. Sweeney who suggested the determination of c. F. R. octane numbers and arranged with the Standard Company for their determination. The oil assistance of A. H. Mazzarola and €3. W. Thomas in the fractionations is gratefully acknowledged.
Literature Cited (1) Egloff, G . , Oil Gas S.,34, No.44,140 (1936). (2) Fenske, M.R., Tongberg. C. O., Quiggle, D., and Cryder, D. S., IND.ENQ.CHEM.,28, 644 (1936). (3) Francis, A.W., Ibid., 18,821 (1926).
VOL. 29, NO, 5
(4) Ipatieff, V. N.,Ibid., 27,1067 (1935). ( 5 ) IPatieff, N., and Corson, B. B . , Ibid., 28,860 (1936). (6) Ipatieff, V.N., and Pines, H., Ibid., 28,684 (1936). (7) McIlhiney, p. C., J.Am. Chem. Sac., 21, 1084 (1899). (8) Mulliken, S. P., and Wakeman, R . L.,IND.ENG. CHEM.,Anal. Ed., 7, 59 (1935). (9) Soday, F. J., and Boord, C. E., S. Am. Chem. Soc., 55, 3293 (1933). (10) Tongberg, C. O., Quiggle, D., and Fenske, M. R., IND. ENQ. CHEM.,28, 201 (1936).
v.
RECEIVED October 2, 1936. Presented before the Division of Petroleum Chemistry at the 92nd Meeting of the American Chemical Society, Pithsburgh, Pa.,September 7 to 11, 1936.
Composition of Citrus Fruit Juices JOHN A. ROBERTS Florida State Department of Agriculture, Winter Haven, Fla.
CITRUS
juice has become in recent years an important article of commerce, primarily because of its dietary value. Knowledge of the mineral content of the juice is useful for two reasons: (a) The mineral content plays an important role in its dietary value, and (6) it may furnish some clue toward better practices in grove fertilization. Data on the complete analysis of citrus juice which would show the relation of ash constituents to the other solids present in the juice are very meager. With the object of supplying these data, the work here reported was undertaken. Analytical data were obtained on the juice and on the ash of the juice. In examining the composition of the ash, chemical methods were used to determine the principle constituents, and spectrographic methods were used to determine the trace elements. Since primary interest was in fruit which was ready for market, samples were taken direct from the packing house. I n order to ensure a sample of adequate size, one-half box (0.8 bushel) was taken for analysis. The data given for each sample are not to be considered statistically representative of variety differences but concern only the sample analyzed.
LEONARD W. GADDUM University of Florida, Agricultural Experiment Station. Gainesville, Fla.
lated from total solids, and percentage of organic matter from water and ash content. All other determinations on the juice were made according to the methods of the Association of Official Agricultural Chemists. Preparation of the ash and TABLEI. DESCRIPTION OF SAMPLES ANALYZED Sample
No. Variety 1 Seedling oranges 2 3 4
5. 6 7
Blood oranges Valencia oranges Lue Gim Gong oranges Marsh wedless grapefruit Seedy (common) grapefruit Tangerines
Location of Packing Date House, Received, County 1936 Polk March Lake March Polk April Polk April Highlands April Highlands April Lake March
all chemical methods were also those of the A. 0. A. C. (Realizing the possibility of contamination of the calcium oxalate precipitates by other metals present in the ash, spectrographic examination of the ignited precipitates was made and the findings are reported here.) Analyses For the spectrographic determinations, a Littrow spectrograph with linear disEersion of about 30 inches (76 cm.) A description of the samples analyzed is given in Table I. between 2250 and 5500 A. was used. About 20 mg. of the All juice was extracted by hand in order to avoid contaminahomogenized material were volatilized in a 220-volt arc tion by metals, and precautions were taken to avoid conusing a current of 9 to 10 amperes. Electrodes of specially tamination bv the oil of the citrus rind. aurified erawhite were In analyzyng the employed. Repeated juice, c i t r i c a c i d , TABLE11. ANALYSISOF CITRUSJUICES spectra of the electotal solids (degrees Marsh trodes were made to Brix), and ratio of Seedensure control of electotal solids to citric SeedVaJen- Lue Gim less Seedy Tanling Blood cia Gong Grape- Grape- gertrode impurities. In acid (maturity ratio) Analysis Orange Orange Orange Orange fruit fruit ine order to avoid fracwere determined by 1.35 1.26 1.05 0.89 1.11 0.98 0.74 Citric acid, % 1.051 1.049 1.048 1.051 1.028 1.039 1.058 tionation during volaSp. gr., 20°/20” C. methods of the Citrus 9.74 14.33 6.95 11.80 12.60 12.65 12.15 Degrees Brix t i l i z a t i o n , the arc 7.22 11.37 Fruit I n s p e c t i o n 7.81 17.09 10.96 12.04 12.00 Maturity ratio * 3.0 3.2 3.0 3.3 3.5 3.63.2 was maintained until Bureau of the Florida 87.30 87.85 88.20 87.40 93.05 90.26 85.67 Eter, % 9.33 13.93 6.73 11.39 12.20 the sample was comOrganic matter 70 12.20 11.67 State Department of 0,099 0.092 0.090 0.094 0.043 0.052 0.069 Nitrogen orgagic % p l e t e l y volatilized. 0.43 0.33 Agriculture (1). The 0.59 0.27 0.56 0.58 0.62 Protein (‘N X 6.2b), % 3.09 3.96 4.32 3.44 3.46 3.95 4.48 Reducing sugar, Yo Spectra of mixtures quinhydrone method 7.89 2.24 1.34 4.89 5.02 4.97 4.86 Sucrose % 6.20 10.98 9.21 4.78 9.34 8.48 8.92 Total &gar % containing v a r y i n g was used t o deter0.025 0.004 0.004 0.007 0.005 0.002 0.006 Pectio acid,’% proportions of t h e mine pH. Percentage 0.453 0.482 0.412 0.403 0.218 0.414 0.401 Ash, % elements served as of water was calcuY
A
MAY, 1937
INDUSTRIAL AND ENGINEERING CHEMISTRY
TPLBLE 111. PRINCIPAL ASHCONSTITVENI :5 Marsh Seedless Lue Gim Blood Valencia Gong Grapefruit Orange Orange Orange In Per Cent of Elements in Juice x 0.187 0.185 0.172 0.157 0.089 0.030 P 0.028 0.010 0.032 0.030 0.009 0.011 0.011 0.016 Ca .~~ 0,008 0.005 0.003 S 0.004 0,002 0.002 0.005 0.010 0.006 0.005 0.005 Mg 0.008 Na 0.009 0.007 0.007 0.004 0.0002 0.0005 Fe 0.0001 0.0001 0.00009 0.0004 0.0008 AI 0.0006 0.0003 0.0003 0.019 0.039 0.035 C 0.032 0,035 0.19 0.20 0 (calcd.) 0.17 0.18 0.093 0.003 0.003 0.003 0.003 c1 0.001 .. In Per Cent of Elements in Ash 41.1 38.3 41.8 x 38.9 40.9 6.60 5.70 P 7.87 7.47 4.82 2.52 2.16 2.74 3.64 3.47 @a 0.881 0.600 0.744 0.744 1.07 S 2.12 1.28 1.37 2.08 1.25 1.65 1.81 1.86 1.69 1.94 0.023 0.024 0.047 0.099 0.039 Fe 0.155 0.092 0.139 0.084 0.163 A1 7.76 8.68 8.68 7.34 8.74 C 0.732 0.752 0.531 0.654 0.688 c1 0 (calcd.) 44.6 38.9 43.0 44.2 42.7 0.080.00080.00010.0001- 0.0008Sr 0.3 0.001 0.003 0.003 0.001 0.0080.00080.080.0001- 0.0008Ba 0.03 0.3 0.003 0.001 0.003 0.0008- 0.0008- 0.0001- 0.00080.0008Cr 0.003 0.003 0.001 0.003 0.003 0.008Mn 0.0080.0050.0030.0080.03 0.03 0.01 0.008 0.03 N. D.a N.D. N.D. N.D. N.D. co N. D. 0.0008- Trace Trace 0,0001Zr 0.003 0.001 Trace N. D. Trace Trace N. D. Ni Trace Trace Trace N. D. 0.0001Ag 0.001 0.0030,0001- 0.0080.0001N. D. Ti 0.008 0.001 0.03 0.001 0.0080.0080.0080.0050.008CU 0.03 0.03 0.01 0.03 0.03 0.0008- 0.008Trace N. D. 0.003Sn 0.003 0.03 0.008 N. D. N.D. N.D. N.D. N.D. Cd N. D. N. D. N. D. N. D. Trace V N. D. N.D. N.D. N.D. N.D. Mo N.D. N.D. N.D. N. D. N.D. Bi N. D. 0.0008- N. D. Trace 0.0008Pb 0.003 0.003 0.0030.0080.0030,0080.01Zn 0.05 0.008 0.03 0.008 0.03 0.0050.0010.0030.00080.0008B 0.008 0.01 0.005 0.003 0.003 Not detected. Seedling Orange
:E
TABLIJI IV.
Seedy Grapefruit 0.171 0.030 0.012 0.004 0.009 0.007 0.00008 0.0007 0.037 0.11 0.002
Tangerine 0.177 0.015 0.014 0.006 0.007 0.006 0.00028 0.0003 0.036 0.17 0.003
41.4 44.1 7.04 3.72 2.94 3.10 0.871 1.38 2.18 1.72 1.71 1.45 0.020 0.070 0.172 0.087 8.90 9.02 0.548 0.802 45.8 42.7 0.0001- 0.00080.001 0.003 0.0008- 0.0080.003 0.03 0.0008- 0.00080.003 0.003 0.0080.030.03 0.08 N. D. N. D. 0.00080.00080.003 0.003 N. D. Trace Trace Trace Trace
N. D . N. D . N. D. N. D. Trace
0.00010.001 0.080.3 0.00080.003 N. D. N. D. N. D. N. D. Trace
0.010.05 0,00080.003
0.0030.008 0.0030.008
>0.1 Trace
ALKALINITYOF ASH
Marsh Lue SeedVelen- Gim less Seedy TanBlood cia Gong Grape- Grape- gerOrange Orange Orange fruit fruit ine 5.69 5.15 5.62 3.06 5.90 5.82 11.6 12.5 14.0 14.0 14.2 14.5 acid necessary to neutralize the ash from 100
Seedling Orange Alkalinityof ash’ 6.31 Alkali numberb 13.9 a Number of ml. of normal grams of sample. b Number of ml. of normal acid necessary to neutralize 1 gram of ash.
standards with which the density of the lines in the spectra of the samples were compared. These density comparisons served as an index to the proportions of the elements present. The data thus obtained are not intended as precision determinations but are indicative of the (‘order of magnitude” of the proportions of the elements present. To avoid misunderstanding as to precision and also to retain a legitimate basis of comparison, the data are presented in (‘range” form. For example, 0.01-0.05 recorded in the tables should be read: The proportion of the element in the sample lies between 0.01 and 0.05 per cent. I n his study of the food value of oranges and grapefruit, Jones (2) gives data on the following elements: calcium, sodium, potassium, magnesium, phosphorus, chlorine, sulfur, and iron. I n so far as these elements are concerned, the results reported are in fairly close agreement. In addition, Table ‘611shows that the citrus juices contain appreciable
675
amounts of manganese and copper, which are of considerable nkxitional value. Also the ash contains other elements not previously reported. Strontium, barium, aluminum, and chromium occur consistently in the samples a n a 1y z e d . Titanium and zinc occur with less consistency; lead, tin, nickel, and silver are found sporadically and could have been introduced either through contamination in the laboratory or through the fertilizers and sprays used.
Calcium Determination In other work it has come to the authors’ attention that the ignited calcium precipitate obtained from the A. 0. A. C. method is contaminated with other metals, in some cases to an appreciable extent. Since this contamination could affect the accuracy of the calcium determination by the official method, the authors felt that some knowledge of the extent of this contamination would be of value. Table V shows data on the spectrographic examination of the precipitates used in the analysis. These results are in accord with the authors’ general experience in the examination of calcium precipitates obtained from a large number of workers. Generally these contaminations were in direct proportion to the amounts of these elements present in the original samples. Since in general the citrus juice ash contained smaller quantities of strontium, barium, etc., than do certain other plant ashes, the contaminations in the present case were relatively low.
Literature Cited (1) Florida Citrus Inspection Bur., Ann. Rept. for 1935-36, pp. 117-22. (2) Jones, D.B., “Food Value of Oranges and Grape-
fruit,” p. 7, U. in 1935.
s. Dept. Agr. pamphlet, published
RnoEIvnr December 23, 1936.
TABLEV. SPECTROGRAPHIC ANALYSISOF IQNITED CALCIUM OXIDEPRECIPITATES USED IN CHEMICAL DETERMINATION OF CALCIUM”
Marsh Seedless Seedy TanConstituBlood Grape- Grapegerentb Orange fruit fruit ine Sr 0.0080.008- 0.0001- 0.0080.03 0.03 0.001 0.03 Ba 0.080.010.0s0.080.008- 0.0008- 0.010.3 0.05 0.3 0.3 0.03 0.003 0.05 Cr 0.001- 0.0008- 0.003- 0.008- 0.0008- 0.001- 0.0010.005 0.003 0.008 0.03 0.003 . . ~0.006 ..... 0.005 Mn 0.0008- 0.0008- 0.003- 0.0050.0008- 0.0030.003 0.003 0.008 0.01 I 0.003 0.008 A1 0.080.03- 0.08- >0.1 0.03- 0.05- 0.05n z 0.3 0.08 0.08 0.1 0.1 co N. D. N. D. N.D. N. D. N. D. N. D. N. D. Zr N. D. N. D. N. D. N. D. N. D. N. D. N. D. Ni 0.03- 0.03- 0.03- 0.003- N. D. N, D. N. D. 0.08 0.008 0.08 0.08 0.0008- Trace 0.003- 0.0001- 0.0008- 0.0008- Trace Ag 0.003 0.008 0.001 0.003 0.003 Ti Trace Trace 0.0008- 0.0008- Trace Trace 0.00080.003 0.003 0.003 cu 0.08- 0.03- 0.08- 0.03- 0.008- 0.03- 0.0080.3 0.08 0.3 0.08 0.03 0.08 0.03 Sn 0.03- 0.03- 0.080.01- 0.003- 0.01 0.050.08 0.08 0.3 0.05 0.008 0.05 0.1 Cd N. D. N. D. N. D. N. D. N. D. N.D. N. D. V Trace N. D. N. D. N. D. N. D. N. D. N. D. Mo N. D. N. D. 0.008- 0.0008- N. D. N. D. N. D. 0.03 0.003 Bi N. D. N. D. N. D. N. D. N. D. N. D. N. D. Pb 0.03- 0.03- 0.030.003- 0.003- 0.008- 0.080.08 0.08 0.08 0.008 0.008 0.03 0.3 a Based on percentage of the dry precipitate. b Magnesium and silicon were present in quantities too great to be estimated on the spectrograph. Seedling Orange >0.1
Va!en- Lue Gim cia Gong Orange Orange 0.0008- 0.030.003 0.08
