UNITED STATES DEPARTMENT OF AGRICULTURE 



BULLETIN No. 454 



Contribution from the Bureau of Plant Industry 

 WM. A. TAYLOR, Chief 



Washington, D. C. 



PROFESSIONAL PAPER 



December 9, 1916 



THE EFFECT OF CULTURAL AND CLIMATIC CONDITIONS 

 THE YIELD AND QUALITY OF PEPPERMINT OIL. 



By Frank Rabak, 

 Chemical Biologist, Drug-Plant and Poisonous-Plant Investigations. 



CONTENTS. 



Page. 

 Introduction 1 



EfEect 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 conn- 

 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. 



60372°— 16 



