364 



Journal of Agricultural Research voi. xiii, no. 7 



Table X. — Production of aldehyde in the olive oil 



The relative amount of aldehyde present in the samples was estimated 

 by the depth of color produced. Air and air-moisture produced a small 

 amount of aldehyde, which was first noticed on the third year. Air- 

 light and air-light-moisture produced a larger amount, first noticed on 

 the second year. Evidently air was the essential factor accelerated by 

 Hght. 



The original olive oil was carefully examined for enzyms by Dr. G. H. 

 Chapman, of this Station, and although their presence was not detected, 

 it is impossible to say whether any of the changes noted were induced or 

 accelerated by their action. 



DISCUSSION OF RESULTS 



Air effected no appreciable change in the color of olive oil for two years ; 

 then it caused a slow but marked destruction fully equal to light at the 

 close. The tintometer for the last two years (191 5-1 91 6) showed air 

 more destructive than light and light-moisture. Air alone was not 

 active in producing rancidity, which was not noticeable until the sixth 

 year. Air had no hydrolytic action but was the active factor in the 

 decomposition of unsaturated acids and in the production of aldehyde. 



Light was more active in destroying color than air or air-moisture, but 

 according to the tintometer for the last two years it did not effect as com- 

 plete destruction as air and air-moisture. Light alone was not active in 

 producing rancidity, which was not noticeable until the sixth year, 

 probably owing to a small amount of inclosed air. Light alone had no 

 hydrolytic action on the glycerids or decomposing action on the unsatu- 

 rated acids. 



Moisture had no effect on the chromogenic bodies and did not appear 

 a factor of any consequence in producing rancidity. Moisture caused 

 the formation of a precipitate and a turbid oil. Moisture was the essen- 

 tial factor in hydrolysis and although only moderately active, gradually 

 effected a considerable amount. 



Air-light, like air-light-moisture, was the most active and effective 

 in destroying color and in producing rancidity, which was noticeable on 

 the second year. Air-light increased the refractive index and viscosity 

 of the oil. Air-light had no hydrolytic action for two years; then it 



