in which D is the weight of dextrose found by analysis A when referred to column 1 of table 104, p. 609; M is the weight of maltose which corresponds to the milliliters of 0.1 N iodine which is obtained if the volume used in analysis A but calculated to Fehling solution by column 2 is deducted from the volume of iodine consumed in analysis B. Tis the weight of total dextrose corresponding to the volume of iodine consumed in analysis C; and W is the weight in milligrams in the respective aliquot samples, that is, 175 mg.

Example.-8.75 g of a glucose sirup was analyzed as described above. Analysis A.-9.17 ml of 0.1 N iodine was consumed. The aliquot contained 175 mg of the original sample. The 9.17 ml corresponds to 26.25 mg of dextrose. 100X26.25 175

Dextrose =

=15 percent.

Analysis B.-16.60 ml of iodine was consumed. According to the table, 9.17 ml of iodine (analysis A) is equivalent to 8.24 ml when the analysis is carried out by the Soxhlet reagents. Hence, by deducting the reduction by dextrose, 16.608.24 8.36, we obtain the reduction caused by maltose. This volume of iodine corresponds to 45.5 mg of maltose by column 3

Analysis C.-21.56 ml of iodine was consumed by a sample half as great as in the preceding analysis. This corresponds, by column 4, to 72.82 mg of dextrose, which, multiplied by 2, equals 145.64 mg from a 175-mg sample. Deduct the dextrose and maltose already present before hydrolysis, that is, 26.25+45.5= 71.75. 90 (145.64-71.75)

Dextrin

=

175

38 percent.

5. REFERENCES

[1] R. F. Jackson, J. Assn. Official Agr. Chem. 13, 198 (1930).

[2] C. A. Browne, J. Am. Chem. Soc. 28, 439 (1906).

[3] C. A. Browne, Handbook of Sugar Analysis, (John Wiley & Sons, New York, N. Y., 1912).

[4] O. Gubbe, Ber. deut. chem. Ges. 18, 2207 (1885).

[5] Wiley Agricultural Analysis 3, 267 (1897).

[6] R. F. Jackson and J. A. Mathews, J. Research NBS 8, 419 (1932) RP426. [7] R. E. Lothrop, J. Assn. Official Agr. Chem. 21, 419 (1938).

[8] A. W. van der Haar, Biochem. Z. 81, 263 (1917). Chem. Weekbl. 13, 1204 (1916). cf. Anleitung zum Nachweis, zur Trennung und Bestimmung der Monosaccharide und Aldehydsäuren (Gebrüder Borntraeger, Berlin, 1920.)

[9] S. F. Acree, Chem. Abst. 15, 2545 (1921).

[10] E. Bourquelot and H. Hérissey, Compt. rend. 129, 339 (1899).

[11] H. Pellet, Bul. assn. chim. sucr. dist. 16, 1181 (1898-99); 18, 758 (1900-1901). [12] C. Neuberg and J. Wohlgemuth, Z. physiol. Chem. 35, 31 (1902). cf. C. Neuberg, Ber. deut. chem. Ges. 35, 2243 (1902).

[13] A. D. Dickson, H. Otterson, and K. P. Link, J. Am. Chem. Soc. 52, 775 (1930).

[14] D. R. Nanji, F. T. Paton, and A. R. Ling, J. Soc. Chem. Ind. 44, 253T (1925). [15] C. A. Browne and M. Phillips, Int. Sugar J. 41, 430 (1939).

[16] R. L. Whistler, A. R. Martin, and M. Harris, J. Research NBS 24, 13 (1940) RP1268.

[17] K. V. Lefèvre and B. Tollens, Ber. deut. chem. Ges. 40, 4513 (1907). [18] W. F. Hillebrand and G. E. F. Lundell, Applied Inorganic Analysis, p. 623

(John Wiley & Sons, New York, N. Y., 1929).

[19] W. B. White, Bul. 234, New York State Dept. of Agr. and Markets (1930). [20] F. W. Zerban and M. A. Wiley, Ind. Eng. Chem., Anal. Ed. 6, 354 (1934). [21] F. W. Zerban, Ind. Eng. Chem., Anal. Ed. 8, 321 (1936).

[22] C. Erb and F. W. Zerban, Ind. Eng. Chem., Anal. Ed. 10, 246 (1938). [23] G. Steinhoff, Z. Spiritusind. 56, 64 (1933).

XI. ANALYSIS OF SPECIAL PRODUCTS

1. HONEY [14]

(a) PREPARATION OF SAMPLE

(1) LIQUID OR STRAINED HONEY.-If the sample is free from granulation, mix it thoroughly by stirring or shaking before weighing portions for the analytical determination. If the honey is granulated, place the container, having the stopper loose, in a water bath and heat at a temperature not exceeding 50° C, with occasional stirring until the sugar crystals dissolve. Mix thoroughly, cool, and weigh portions for the analytical determinations. If foreign matter, such as wax, sticks, bees, particles of comb, etc., is present, heat the sample to 40° C in a water bath and strain through cheesecloth in a hotwater funnel before weighing portions for analysis.

(2) COMB HONEY.-Cut across the top of the comb, if sealed, and separate completely from the comb by straining through a 40-mesh sieve. When portions of the comb or wax pass through the sieve, heat the sample as in (1) and strain through cloth. If the honey is granulated in the comb, heat until the wax is liquefied; stir, cool, and remove the wax.

(b) MOISTURE

Proceed as directed under (c), page 262 of this circular.

(c) ASH

Weigh 5 to 10 g of honey into a platinum dish, add a few drops of pure olive oil to prevent spattering, heat carefully until swelling ceases, and ignite at a temperature not above dull redness until a white ash is obtained.

(d) DIRECT POLARIZATION-TENTATIVE

(1) IMMEDIATE DIRECT POLARIZATION.-Transfer 26 g of the honey to a 100-ml flask with water, add 5 ml of alumina cream, dilute to the mark with water at 20° C, filter, and polarize immediately in a 200-mm tube.

(2) CONSTANT DIRECT POLARIZATION.-Complete the mutarotation by allowing the solution prepared for polarization to stand overnight before making the reading or by adding a few drops of NH2OH to the solution before making to volume. If necessary to conserve the sample, the solution from the tube used in the immediate direct polarization (1) may be returned to the flask. Make the final reading at 20° C in a 200-mm tube.

(3) MUTAROTATION.-The difference between (1) and (2) is a measure of the mutarotation.

(4) DIRECT POLARIZATION AT 87° C.-Polarize the solution obtained under (2) at 87° C in a jacketed 200-mm metal tube, preferably of silver.

(e) INVERT POLARIZATION-TENTATIVE

(1) AT 20° C.-Invert 50 ml of the solution obtained under (d), using either invertase or hydrochloric acid as directed on pages 157-58, or page 155 this Circular, and polarize at 20° C in a 200-mm tube. (2) AT 87° C.-Polarize the solution obtained under (1) at 87° C in a 200-mm tube.

(f) REDUCING SUGARS

Dilute 10 ml of the solution used for direct polarization (d) to 250 ml and determine reducing sugars in 25 ml of this solution by Lane-Eynon method, p. 185, or by the Munson-Walker method, p. 170, of this Circular. Calculate the result to percentage of invert

sugar.

(g) SUCROSE

(a) Calculate from the data given in (d) (2) and (e) (1) if inversion is made by invertase, as directed on page 157. Use the formula given on page 158.

FIGURE 40.-Apparatus for high-temperature polarization.

Multiply the direct reading at 87° C, (d) (4), by 1.0315, and subtract the product from the constant direct polarization at 20° C, (d) (2); divide the difference by 2.3919 to obtain grams of levulose in a normal weight of honey. From this figure calculate the percentage of levulose in the original sample.

Multiply the percentage of levulose (h) by the factor 0.915, which gives its dextrose equivalent in copper-reducing power. Subtract the figure obtained from that of the reducing sugars (f), calculated as dextrose, to obtain the dextrose in the sample. Because of the difference in the reducing powers of the different sugars, the sum of the dextrose thus found and the levulose as obtained under (h) will be greater than the quantity of invert sugar obtained under (f).

(j) DEXTRIN (APPROXIMATE)—TENTATIVE

Using not more than 4 ml of water, transfer 8 g of the sample (4 g in the case of dark-colored honeydew honey) to a 100-ml flask by allowing the sample to drain from the weighing dish into the flask and then dissolving the residue in 2 ml of water. After adding this solution to the contents of the flask, rinse the weighing dish with two 1-ml portions of water, adding a few milliliters of absolute alcohol each time before decanting. Fill the flask to the mark with absolute alcohol, shaking constantly. Set the flask aside until the dextrin has collected on the sides and bottom and the liquid is clear. Decant the clear liquid through a filter paper, and wash the residue in the flask with 10 ml of 95-percent alcohol, pouring the washings through the same filter. Dissolve the dextrin in the flask with boiling water and filter through the filter paper already used, receiving the filtrate in a weighed dish prepared as directed on page 262, (c). Rinse the flask and wash the filter a number of times with small portions of hot water, evaporate on a water bath, and dry to constant weight at 70° C under a pressure of not more than 50 mm of mercury.

After determining the weight of the alcohol precipitate, dissolve the latter in water and make up to definite volume, using 50 ml of water for each 0.5 g of precipitate or part thereof.

Determine reducing sugars in the solution both before and after inversion by the method of Munson and Walker, p. 170, expressing the results as invert sugar. Calculate sucrose from the results thus obtained, and subtract the sum of the reducing sugars before inversion and sucrose from the weight of the total alcohol precipitate to obtain the weight of the dextrin.

(k) FREE ACID

Dissolve 10 g of the honey in water and titrate with 0.1 N NaOH solution, using phenolphthalein indicator. Express the results in terms of milliliters of 0.1 N NaOH required to neutralize 100 g of the sample.

(1) COMMERCIAL GLUCOSE

(1) QUALITATIVE TEST-TENTATIVE.-Dilute the honey with water in the proportion of 1:1 and add a few milliliters of iodine solution (1 g of I, 3 g of KI, 50 ml of water). In the presence of commercial glucose the solution turns red or violet, the depth and character of the color depending upon the quality and nature of the glucose used. A blank test with a pure honey of about the same color should be made in order to secure an accurate color comparison. Should the honey be dark and the percentage of glucose very small, precipitate the dextrin that may be present by adding several volumes of 95-percent alcohol. Allow to stand until the precipitate settles (do not filter), decant the liquid, dissolve the residue of dextrins in hot water, cool, and apply the above test to this solution. A negative result is not proof of the absence of commercial glucose, as some glucose, especially of high conversion, does not give reaction with I. [2]

(2) QUANTITATIVE METHOD TENTATIVE. An approximate determination can be made by Browne's formula as follows: Multiply the difference in the polarizations of the invert solution at 20° and 87° C, (e) (1) and (e) (2), p. 232, by 77, and divide this product by the percentage of invert sugar found in the sample after inversion. Mul

tiply the quotient by 100 and divide the product by 26.7 to obtain the percentage of honey in the sample; 100 percent minus the percentage of honey gives the percentage of glucose. [2]

(m) COMMERCIAL INVERT SUGAR [3]

(1) RESORCINOL TEST [4]-TENTATIVE.

a. Resorcinol solution.-Dissolve 1 g of resublimed resorcinol in 100 ml of HCl (sp gr 1.18 to 1.19).

b. Determination. Introduce 10 ml of a 50-percent-honey solution into a test tube and add 5 ml of ether. Shake gently and allow to stand for some time until the ether layer is clear. Transfer 2 ml of this clear ether solution to a small test tube and add a large drop of the recently prepared resorcinol solution. Shake, and note the color immediately. A cherry-red color appearing at once indicates the presence of commercial invert sugar. Yellow to salmon shades have no significance. (2) ANILINE CHLORIDE TEST [5]-TENTATIVE.

a. Reagent. Aniline chloride solution. To 100 ml of chemically pure aniline add 30 ml of 25-percent HCl.

b. Determination.-Introduce 5 g of the honey into a porcelain dish and add, while stirring, 2.5 ml of the recently prepared aniline reagent. In the presence of commercial invert sugar, the reagent assumes immediately an orange-red color turning dark red. Yellow to salmon shades have no significance.

The resorcinol test and the aniline-chloride test, when negative, may not be regarded as conclusive evidence of the absence of commercial invert-sugar sirup in honey.

(n) DIASTASE [6]-TENTATIVE

Mix 1 part of honey with 2 parts of sterile water. Treat 10 ml of this solution with 1 ml of 1-percent soluble starch solution and digest at 45° C for an hour. At the end of this time test the mixture with 1 ml of iodine solution (1 g of I, 2 g of KI, 300 ml of water). Treat another 10 ml portion of the honey solution, mixed with 1 ml of the soluble starch solution without heating to 45° C, with the reagent and compare the colors produced. If the original honey has not been heated sufficiently to destroy the diastase, an olive green or brown coloration will be produced in the mixture that has been heated at 45° C. Heated or artificial honey becomes blue.

(1) SIRUP.

2. MAPLE PRODUCTS [7, 14]

(a) PREPARATION OF SAMPLE

For solids determination.--If the sample contains no sugar crystals or suspended matter, decant sufficient of the clear sirup for use in the determination. If sugar crystals are present, redissolve them by heating. If suspended matter is present, filter the sample through cotton wool.

For other determinations.-If sugar crystals are present, redissolve them by heating. If other sediment is present, distribute it evenly through the sirup by shaking. Transfer approximately 100 ml of the sirup, with its suspended sediment, to a casserole or beaker, add one-quarter the volume of water and evaporate over a flame. When the temperature of the boiling sirup approaches 104° C, draw a small