Due to the investigations of M. E. Jaffa and his associates at the University of California, much light has been thrown on the food value of the avocado in recent years. The following table shows the composition of several well-known varieties, one of each of the recognized horticultural races, and the hybrid Fuerte. In presenting this table, which is based on the work of Jaffa, it is necessary to explain that the proportions of the constituents have been found to change in each variety according to the degree of maturity of the fruits. They may fluctuate also in different years. Variation is particularly noticeable in regard to the fat-content. For example, in specimens of the Chappelow examined at different times, the percentage of fat ranged from approximately 14 to 30, while in specimens of the Challenge it ran from 3 to 17. Fruits showing the lowest percentages were immature at the time the analyses were made, but they were no more so, probably, than many which are put on the market. Up to a certain point, the fat-content increases with the maturity of the fruit: after this point is reached, there is quite often no further increase, no matter how long the fruit may remain on the tree.
The total dry matter in the edible portion of the avocado is greater than in any other fresh fruit, the one nearest approaching it being the banana, which contains about 25 per cent. An average of twenty-eight analyses showed the avocado to contain about 30 per cent.
Trapp .... (West Indian)
Puebla .... (Mexican)
Fuerte .... (Hybrid)
The protein-content, which has been found to average about 2 per cent, is higher than that of any other fresh fruit.
The percentage of carbohydrates is not high compared with that of many other fruits, because the avocado contains almost no sugar. F. B. La Forge of the Bureau of Chemistry at Washington has found in the avocado a new sugar, called D-Mannoketoheptose, which is believed to be present in amounts varying from 0.5 to 1 per cent.
The amount of mineral matter is much greater than is found in other fresh fruits. Soda, potash, magnesium, and lime compose more than one-half the ash or mineral matter, which places the avocado among the foods which yield an excess of the base-forming elements, as opposed to nuts, which furnish acid-forming elements in excess.
Jaffa 1 says: "So far as protein and ash in fresh fruits are concerned, the avocado stands at the head of the list, and with reference to the carbohydrates, contains on an average fully 50 per cent of that found in many fresh fruits. These facts alone would warrant due consideration being given to the value of the avocado as a fresh fruit. Its chief value as a food, however, is due to its high content of fat. This varies, as shown by the analysis, from a minimum of 9.8 per cent to a maximum of 29.1 per cent, with an average of 20.1 per cent. The only fruit comparable with the avocado in this respect is the olive."
Experiments carried on at the University of California have shown that the digestibility of avocado fat is equal to that of butter-fat, and not below that of beef fat.
As to the caloric or energy-producing value of the avocado in twenty-eight varieties examined, one pound of the flesh represents an average of 1000 calories. The maximum and minimum were 1325 and 597 respectively. The maximum "corresponds to about 75 per cent of the fuel value of the cereals and is not far from twice that noted for average lean meat."
In the following table the avocado is compared, in caloric value, with several common foodstuffs. For this comparison a pound of avocado flesh has been considered to represent 1000 calories; this is not showing the avocado at its best, for, as just stated, in some varieties a pound represents over 1300 calories:
100 grams (about 3½ oz.) boiled rice...............
100 grams white bread...............
100 grams avocado....................
100 grams egg..........................
100 grams lean beef........................................
It must not be assumed from the figures that the avocado has a total food value greater than that of lean beef. It is only the caloric or energy-producing values that are shown, and much of the value of meat as a food lies, of course, not in the energy which it produces, but in its ability to build up and repair the tissues of the body.
1 Bull. 254, Calif. Agr. Exp. Sta.
In the United States the avocado is commonly used in the form of a salad, either alone or combined with lettuce, onions, or other vegetables. Up to the present, no satisfactory ways of cooking or preserving this fruit have been developed. Experiments in extracting a table- or cooking-oil have been encouraging, but as yet the production of avocados in this country is not great enough to permit the commercial development of this field. In the tropics, the fruit is added to soups at the time of serving; mashed with onions and lemon juice to form the delectable guacamole of Cuba and Mexico; or eaten as a vegetable, without the addition of any other seasoning than a little salt. In Brazil it is looked on more as a dessert than as a staple foodstuff, and is made into a delicious ice-cream. Numerous recipes appear in cook-books which have been published in Cuba, Florida, California, and Hawaii.