CITRUS Byproduct Uses May Greatly Influence Fresh-Fruit Market

In the statistical section of this Yearbook will be found data showing the production of citrus fruits in the United States. These figures show that production is increasing rapidly. The rate of increase is greater than that of population. This means that the demand must be extended by creating new markets or new uses. Foreign markets are being supplied in part by other recently developed citrus-growing areas such as Palestine, South Africa, and Australia. Canned grapefruit has created a market for itself which can no doubt be extended. Because of its less perishable nature it is better adapted for distant markets than fresh fruit. Why should the citrus industry limit itself to only one product in exploiting these markets?

Virtually Noncompetitive Uses Available

Some citrus products may enter into competition with fresh fruit while others will have uses so far removed that competition will not be felt. Under citrus products which may compete may be listed canned grapefruit hearts and juice, and canned orange juice. When such products go to new markets or into new uses there is no competition and they may even serve to create a demand for citrus fruits. Many people have learned to eat grapefruit because they tried the canned product and immediately liked its milder flavor.  There is a second class of products such as marmalades and beverages which in no way compete with the fresh fruit.

The Citrus Products Station of the Bureau of Chemistry and Soils at Winter Haven, Fla., has succeeded in developing on a laboratory scale a full line of alcoholic citrus beverages such as wines, brandies, and cordials. The wines are prepared by adding corn sugar to increase the sugar content of the juice to about 25 percent, inoculating with a pure culture of wine yeast, and allowing fermentation at a low temperature. The fermentation is followed by clarification and aging.  Two distinct types of citrus wine have been prepared, one resembling a sauterne, the other a sherry. Brandies were prepared by distilling fermented sweetened citrus juices. Cordials were prepared by adding sugar, water, and oil from the peel of citrus fruits to citrus brandies.  The results of this work point to the possible large-scale utilization of surplus and cull citrus fruits in the manufacture of products not in competition with fresh fruit.

These products are well adapted to large-scale manufacture at relatively low cost and to the utilization of surplus fruit not taken by other uses in that the quantity used in any single year can be adjusted to supply. Excess production of these products in a season of bountiful yield can be carried over to years of low yield with no deterioration but actual improvement in quality.

The preservation of unfermented orange juice by heat has not become of such commercial importance as that of grapefruit juice because of the difficulties encountered in retaining the flavor of the fresh juice.  Results obtained during the past 3 years indicate that flash pasteurization following deaeration is well suited for the production of a satisfactory commercial product. The method consists of cutting the fruit in half and extracting the juice from the halved fruit on slowly revolving ribbed cones. Because flavor changes are due primarily to oxidation, the reamed juice is immediately deaerated. This is accomplished by exposing the juice in thin layers to a vacuum of about 28 inches, thereby removing a considerable quantity of the dissolved gases. Although deaeration is not complete, this treatment has been found highly beneficial. After deaeration, the juice is pumped through the flash pasteurizer, consisting of a coil of tin pipe whose walls are about 2 millimeters apart, and surrounded by a steam jacket. Here the juice is exposed to a temperature not higher than 205° F. for approximately 5 seconds. It is then immediately cooled to 160° and filled into the containers at this temperature. The ‘closed cans are cooled in running water. The process is continuous, and the juice, after being extracted from the fruit, is sealed within the final container in about 5 minutes.

Flash-pasteurized grapefruit juice yields a product superior to that obtained by exhausting and then sterilizing as now generally practiced on a commercial scale.

The criterion of the value of flash pasteurization rests on the stability of the product during periods of storage. It has been found that flash-pasteurized orange juice protected from high storage temperatures will retain an acceptable flavor for at least a year or even longer.

Both the alcoholic and the nonalcoholic types of citrus products have definite and promising commercial possibilities and thus will provide additional returns to the grower.

H. W. VON LOESECKE and H. H. MOTTERN, Bureau of Chemistry and Soils.