PROCESS OF RIPENING IN TEtE TOMATO. 15 



METHODS OF ANALYSIS. 



Sampling and preservation. — In order to obtain representative 

 samples at each stage of ripening and to avoid the necessity of 

 analyzing a large number of individual fruits to determine existing 

 variations, composite samples were resorted to. These composite sam- 

 ples were taken from approximately 20 tomatoes. To eliminate error 

 due to possible correlations between size and chemical composition, 

 tomatoes were chosen so that each composite sample was obtained from 

 fruits of all sizes, with the exception of abnormally large or small 

 fruit which were discarded. The method of collecting the samples 

 was uniform throughout. Where the fruits were small (e. g., those 

 14 days old) a 200-gram lot was made by using entire tomatoes, but 

 with larger fruit samples of 200 grams were made up by removing a 

 cylinder from each tomato with a half-inch cork borer. The cylinders 

 were taken through the equator perpendicularly to the axis. A fairly 

 representative sample was obtained in this manner, for the portion 

 removed from each tomato was roughly proportional to the size of 

 the whole fruit. The method of preserving samples for analysis was 

 similar to that used by Hasselbring and Hawkins (21) in their studies 

 of sweet potatoes and identical with the procedure of Kraus and 

 Kraybill (28) with tomatoes. The material was heated with 80 per 

 cent alcohol for 1 hour at 70° to 75° C, with the addition of cal- 

 cium carbonate (CaC0 3 ) to insure the neutralization of acids. Two- 

 quart glass-top jars were used, and approximately 1,065 c. c. of 95 

 per cent alcohol and 0.5 gram of precipitated CaC0 3 were added, 

 after which the heating was carried out on a boiling water bath. 

 Moisture and ash samples were merely covered with 95 per cent 

 alcohol without subsequent heating. 



In preparing the samples for analysis (with the exception of certain 

 moisture, dry-weight, and ash samples) the alcohol was removed from 

 the insoluble residue by filtering into a 2-liter volumetric flask. The 

 residue was thoroughly extracted with warm 80 per cent alcohol, 

 which was cooled, filtered, and added to the original filtrate. The 

 volume of the flask was then made up to mark at 20° C. (referred 

 to later as the original extract) and one-tenth and three-twentieths 

 aliquots pipetted off and placed in separate Florence flasks, which 

 were stoppered, labeled, and set aside. The residue was dried at 

 80° C. in an air oven for a few days and then allowed to come to 

 air-dry weight, after which it was weighed and finely ground in a 

 drug mill (referred to later as the original residue) . One-tenth and 

 three-twentieths portions were weighed and stored in small stop- 

 pered vials. 



Moisture, dry weight, and ash. — An entire 200-gram sample covered 

 with 95 per cent alcohol was placed in a large beaker and evaporated 

 nearly to dryness on a steam bath. It was then transferred to a 



