CALIFORNIA A\'OCADO ASSOCIATION 



61 



In the case of the avocado, the flesh contains no starch from which sugar 

 can be produced after harvesting; indeed, sugar plays no appreciable part in the 

 composition of its flesh, and in all probability gives no indication of maturity. In 

 fact, so far as the limited data on hand go, they show less sugar by far in the 

 matured fruit than in the green. Apparently also the sugar decreases after the 

 fruit is removed from the tree. 



We must, therefore, turn to other constituents to determine the maturity of 

 the fruit, and naturally the oil content presents the best indication of success. From 

 what the oil content of the avocado is derived, I cannot say at this time. I can say 

 that in all the varieties examined by us the oil content increases as the avocado 

 matures. The actual am.ount of oil in some varieties increases to a shght extent 

 after the fruit is removed from the tree. With varieties that are now mature, 

 there has been an increase of nearly 400% in the oil content since we began the 

 analysis in September. 



If the oil content is the best indication of the maturity of the fruit, the 

 question at once arises as to the practicability of such a standard to the grower. 

 Manifestly one of two things must be accomplished in order to make it possible for 

 him to utilize the information. Either a simple method for the determination of 

 oil must be devised or the oil content must be correlated with some physical char- 

 acteristic of the fruit which can be readily distinguished. Fortunately both meth- 

 ods seem possible of accomplishment. It does not seem at all difficult to adopt the 

 Babcock test, used for fat determinations on milk, to properly prepared avocado 

 pulp. Also there are certain characteristics developed by the fruit as it matures 

 which it may be possible to utilize as an indication of maturity. At the present 

 price of avocados, the oil determination method, it is believed, will not become 

 popular, for manifestly the fruit will have to be destroyed for the test, so that we 

 are concentrating on the study of the correlation method. 



With many fruits, it is easily possible to predict maturity from the physical 

 characteristics of the fruit. Usually color is thought to be the first evidence of 

 ripening, and often is. But it is also true that some fruits color before they be- 

 come palatable. Next to color, the "feel" of the fruit is most often used; not 

 many fruits can be left on the tree, however, long enough to become soft, as the 

 shipping quality would be lost. The color of the stem is also an indication of 

 maturity. With some fruits the color and condition of the seed or seeds is some- 

 times used. In the case of Bartlett pears, the color of the seed is taken by many 

 growers as an indication of ripening, and also the ease with which the stem 

 can be broken from the branch. 



One naturally looks to the seed as a good indication of maturity, but this 

 examination is not available in the case of the avocado at present, as the fruit is 

 too expensive. We have been observing carefully the appearance of the seed as 

 the fruit grows, and there is a marked change, but the only indication given from 

 the outside is the loosening of the seed in its cavity and when this stage is reached, 

 the fruit of some strains at least is over ripe. Advanced maturity is often indicated 

 by the facility with which fruit separates from the twig, but too often this takes 

 place only after it is too ripe for commercial use. The avocado separates naturally 

 from the fruit spur in two places, one at the junction of the fruit and its stem, 

 the other at the point where the fruit stem is attached to the parent plant. In our 

 experience, many strains of avocados are mature enough to store before they will 

 separate readily at either point. So far, the physical characteristics which seem 

 to us to give the best indication of maturity are the color of the fruit and of the 

 stem. 



