UNITED STATES DEPARTMENT OF AGRICULTURE 
BULLETIN No. 454 j 
^-* Contribution from the Bureau of Plant Industry 
J\&&jC wm - a - taylor > CIlief 
Washington, D. C. PROFESSIONAL PAPER December 9, 1916 
THE EFFECT OF CULTURAL AND CLIMATIC CONDITIONS ON. 
THE YIELD AND QUALITY OF PEPPERMINT OIL. 
By Frank Rabak, 
Chelnical Biologist, Drug-Plant and Poisonous-Plant Investigations. 
CONTENTS. 
Page. 
Introduction 1 
Effect of soil and climate on the composition 
of peppermint oil 2 
Yield of oil from fresh and from dry plants at 
various stages of growth 3 
Physical and chemical properties of pepper- 
mint oil from fresh and from dry plants at 
various stages of growth 5 
Effect of light and shade 11 
Effect of frost action 12 
Conclusions 15 
INTRODUCTION. 
The peppermint plant, known botanically as Mentha piperita L., 
is cultivated extensively both in the United States and foreign coun- 
tries as the source of a volatile oil which is widely used as a flavoring 
and therapeutic agent. The value of the oil depends much upon its 
composition. The principal ester constituent, menthyl acetate, pos- 
sesses a very fragrant minty odor, to which the agreeable aroma of 
the oil is largely due. The alcoholic constituent, menthol, possesses 
the well-known penetrating minty odor and characteristic cooling 
taste. The flavoring properties of the oil are due largely to both the 
ester and alcoholic constituents, while the medicinal value is attributed 
to the latter only. The elaboration of these constituents depends 
upon the various cultural and climatic conditions to which the plant 
is subjected during growth. 
In order to obtain data bearing on possible variations in the com- 
position of peppermint oil under varying conditions, plants were 
grown under various conditions of soil and climate and were har- 
vested at various stages of growth. The oil was distilled from certain 
parts and also from the entire herb in both the fresh and the dry 
condition and was then subjected to thorough examination. 
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