46 



ANNUAL REPORT 1920 AND 1921 



so that the results must be studied with this fact in mind. Practically all of the 

 trees used were young, strong growing specimens, bearing 25 to 75 fruits. Monthly 

 samples of fruit consisting of from 2 to 6 avocados were taken. 



When these samples were received at the laboratory, one half of the number 

 taken were analyzed at once; the other half were carefully wrapped in paper, 

 laid aside until the flesh had softened satisfactorily, and then subjected to anal- 

 ysis. If for any reason, either analysis had to be delayed, the samples were 

 kept in cool storage (from 35 to 45° F.) until used. In the text, the samples 

 analyzed at once are referred to as hard samples, while those not Jinalyzed until 

 they had softened are called soft samples. 



In preparing them for analysis, the fruits were weighed first in air and then 

 under water, and the specific gravity calculated. They were then halved, the 

 seed carefully removed and the flesh scraped from the skin with a spoon. In 

 the case of immature fruit, where the analyses were made before the flesh had 

 softened, this separation was very difficult and in a great majority of cases, the 

 skin was removed by paring with a knife. The skin, seed and flesh were each 

 weighed and their proportion calculated. 



The flesh of the fruits was finely ground by passing through a food grinder 

 repeatedly, and the following determinations were made upon it: Water, ash, 

 protein, fat, sugar and crude fiber. The methods of the Association of Official 

 Agricultural Chemists were used and need not be further described, except to 

 say that water was determined by mixing the pulp with asbestos fiber and drying 

 in vacuo at 70° C. 



Significance of the Determinations Made 



The specific gravity of the fruit chiefly indicates its texture or compactness. 

 Avocados with loose seeds and hollow centers have a low specific gravity. 



The moisture which the fruit contains is not indicative of its quality as far 

 as our observations go; green fruit contains more water than ripe, for, as the 

 proportion of fat increases, the proportion of water decreases. 



So far as the study of maturity goes, ash is a relatively unimportant con- 

 stituent of the avocado. It has, however, some importance when food values 

 are considered. Protein is a very important food material and occurs in unusual 

 quantities for a fruit, but does not vary greatly as the avocado matures. 



Fat is the characteristic constituent to which the fruit owes its popularity. 

 It must not be thought, however, that fat alone is the determining factor in the 

 quality of a variety. The amount of this constituent increases rapidly as the 

 fruit matures, and affords one basis for the study of the maturity. 



Sugar is relatively not important, but is extremely interesting both on 

 account of its constitution and its disappearance as the fruit matures. 



Tables I to IX 



Discussion of the Data 



The data derived from the analysis of the samples are presented in nine 

 tables. For better comparison, the hard samples and soft samples picked at the 

 same time are grouped in the tables. In order to better compare the varieties, a 

 table is also given showing the composition of each variety at the time of its 

 maximum fat content. The results in this table are from the fruit that had been 

 stored until soft. A figure is also given which illustrates the changes in fat 

 content of each variety as it matures. 



