RECENT WORK IN AGRICULTURAL SCIENCE. 



AGRICULTURAL CHEMISTRY— AGROTECHNY. 



Tlic odorous constituents <»1" apples. — Emanation ol" acetaldeliyde from 

 tlie ripe fruit, F. B. Powkk uiid V. K. Chesnut {Jour. Aiiier. Vhem. Soc, k' 

 (19^U), Xo. 7, pp. 1509-15^6). — A detailed investigation of tlie chemical nature 

 of the odorous constituents of apples is reported from the Bureau of Chemistry, 

 U. S. Department of Agriculture. The varieties of apples used in the investiga- 

 tion inchuled the Ben Davis, Springdale. and a variety of crab apples known as 

 the Golden Beauty. 



The i)reliminary extraction of the odorous constituents was effected by pro- 

 longed disliiiatioii with steam of fresh parings from the apples ami repeated 

 cohohatiuu of the aciueous distillate in a current of steam until the distillate 

 was concentrated to about one-hundredth of its original volume. A detaileu 

 chemical study of this distillate and of the aqueous liquids remaining from the 

 concentration of the original distillate led to the following conclusions : 



" The odt)rous constituents of api)les have been found to consist essentially of 

 the aniyl esters of formic, acetic, and caproic acids, with a very small amount 

 of the caprylic ester and a considerable proportion of acetaldeliyde. In consid- 

 ering the relative amounts of the respective alcohols and acids it seems probable 

 that the latter are also present to some extent in the free state. 



" It has been shown that acetaldehyde is a product of the vital activities of 

 the fruit, and that it occurs in the exhalations of ripe apples. This observation 

 is deemed of considerable biological importance, especially as it has hitherto 

 been assumed that the lower aliphatic aldehydes are tirst formed during the 

 process of steam distillation. It is, for example, quite probable that the 

 exhalation of acetaldehyde may prove to be one of the factors involved in the 

 production of so-called 'apple-scald,' an affection to whicli some apples are 

 subject when stored without free circulation of ail". 



" The acpieous distillate from fresh apple parings has been found to contain, 

 in a<ldition to the above-mentioned substances, exceedingly small amounts of 

 methyl and ethyl alcohols and also a small amount of furfural. Inasmuch as 

 the last compound is doubtless produced by chemical changes in the material 

 during its distillation, it can not be regarded as one of the odorous con.stituents 

 of the apple. 



"The essential oil, as extracted by means of ether from a concentrated dis- 

 tillate of either ordinary apple parings or those of the crab apple, is at ordinary 

 temperatures a yellowish, .somewhat viscid li<iuid, becoming much darker on 

 keeping. When slightly cooled it forms a concrete mass, due to the separation 

 of small acicular crystals which consist of a paraffin hydrocarbon. It possesses 

 In a high degree the characteristic, fragrant odor of fresh apples. Besides the 

 esters mentioned, it has been found to contain, by specific tests, small amounts 

 of acetaldehyde and furfural. The yield of oil from the parings of the Ben 

 Davis apple was O.CH)35 per cent, and that from the more odonuis crab apple 

 0.0043 per cent, which corresponds to about 0.0007 and 0.UO13 per cenr, respec- 

 tively, of the entire ripe fruit. 



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