12 CHEMICAL COMPOSITION OF SOME TROPICAL FRUITS. 



ORANGE (NARAN.TA). 

 ( Citrus aurantium.) 



The oranges of Cuba as a rule are smaller, more fibrous, and con- 

 tain more seeds than the same varieties grown in this country, but 

 they are very juic} T and have a good flavor. These qualities could 

 undoubtedly be improved by modern methods of selection, grafting, 

 and cultivation. The fruit retails at a very low price in the Havana 

 market, sometimes selling for 50 cents a hundred, although the usual 

 price is from 60 cents to $1. 



Two varieties of orange (Citrus aurantium) were found, one a thin- 

 skinned small fruit known as the "china," and the other a much 

 larger fruit with a thick skin. The former is superior in quality, 

 having less fiber and a better flavor. Table I, on citrus fruits and 

 preserves, giving the composition of these fruits, shows that there is 

 but a slight difference between these varieties in the content of sugar. 

 The " china", however, contains twice as much acid and only one-fourth 

 the amount of insoluble solids as the thick-skinned orange. In this it 

 resembles the American varieties, the analysis of 80 samples of which 

 gave 1.28 per cent of acid and 10.68 per cent of sugars/' 



In sample No. 506, Table I, the very exceptional fact is noted that 

 the polarization after inversion was to the right, showing a different 

 ratio between the dextrose and levulose than that which usually 

 exists in fruits, right-hand readings being very rare. In some pre- 

 vious work on fruits done in this Bureau* an exception of this kind 

 was also noted in the case of a sample of plums which after inversion 

 gave a reading of +1.3. 



The bitter orange, "naranja agria" (Citrus bigaradia), resembles 

 the large, thick-skinned, sweet orange in appearance, having a some- 

 what thicker skin, but being about the same size. It grows in a semi- 

 wild state in many parts of the island, but is little used except for 

 making "dulces" (sweets). Some of the finest Cuban preserves are 

 made from this fruit. The chief difference between this variety and 

 the sweet orange is in the amount of acid present, both containing 

 about the same amount of sugars. 



Four kinds of orange preserves were examined. ''Pasta de naran ja " 

 is a thick orange paste sold in wooden boxes lined with paper. This 

 packing is not sufficient to protect the preserves, as a sample kept in 

 the laboratory dried out and became wormy in the course of a year. 

 The paste was probably made by boiling down the pulp and inner skin 

 of the orange. Owing to the small amount of acid present but little 

 of the cane sugar was inverted. 



"Cull.v. California Agr. Expt. Sta. Rept., 1shl>-!»:;, j>. 246. 

 '>['. s. Dept. of A.gr., Bureau of Chemistry, Fruits and Fruit Products: Chemical 

 and Microscopical Examination, Bui. No. <i<i. p. 19. 



