The Olive

by K. G. Bitting

The olives are placed in an alkaline solution, usually sodium hydrate as it is stronger in action than potassium hydrate. The strength varies with the different packers but is generally in the neighborhood of 1½%. After 6 to 8 hours, the lye is drawn off and the olives exposed to the air in order that they may oxidize and darken, since the lye removes some of the natural color. The operation is repeated with the same strength or less of lye solution and the fruit exposed to the air until examination of the pulp shows that the lye has penetrated to the pit. The lye solution is then replaced with clear water which is changed twice a day, until the lye and bitterness are removed, which requires from 4 to 8 days. The olives are then treated with brine solutions, starting with 1%, and increasing the strength at intervals of about 2 days until about 4% is used, when they are ready to be put in glass jars or cans and sealed.

The brine is used very weak at the start and gradually increased so that the osmotic action may be so controlled as not to cause the fruit to shrivel as it would if placed in a strong solution at the start. Some packers permit the olives to stay in the weak brine long enough for fermentation to take place as done with the imported green olives so as to develop an acid flavor. The more recent tendency, however, is toward packing them with the least possible change, and to depend upon the distinctive natural flavor of the fruit itself. A similar tendency toward retaining the natural color, rather than that induced by oxidation, might be advantageous.

If it be the intent to hold the olives in bulk, they are treated with increasingly strong brines until 10

to 12½% is used, the latter amount being required to carry them safely through the summer.

The process is modified in practise to suit the conditions, as variations in varieties of fruit, in temperature, and in the lye have to be considered. There are also variations in practise due to individual experience. During the time the olives are in the various solutions they are stirred frequently, so as to change their position in the vats, and also to change the solution in contact with them. The stirring was, and is done yet in some cases, by hand, with wooden paddles, which is laborious besides causing more or less damage to the fruit. Recently compressed air has been piped to the vats and directed into the solutions with sufficient force to keep the olives agitated. This method is said to hasten the action of the lye solutions with consequent improvement in the fruit. It also obviates the drawing off the solutions and the exposure of the fruit to the air, as a certain amount of oxidation takes place in the solution.

As the operators place the olives in the bottles or cans, the soft and defective ones are discarded. The containers are then filled with a 3% brine at a temperature of 175 or 180 degrees F. The air is exhausted, during which the temperature is raised to 185 degrees, and the containers sealed, after which they are processed. The large olives in a 26 ounce glass jar are cooked for 50 minutes; extra large, 55 minutes; mammoth, 58 minutes; and colossal 60 minutes; at 240 degree F. in some factories, or for a longer period if processed at a lower temperature.

The time required for heat to penetrate to the center of an olive is longer than has been generally supposed. This was determined by carefully drilling into the pit, first with a fine drill and then with increasingly larger ones, until an eighth inch hole was made. The bulb of a small thermometer was inserted, and to prevent heat being carried to the bulb by means of the glass stem, sections of olives were placed around the stem immediately above the olive being tested, and tied securely. Jumbo olives at room temperature placed directly in a boiling bath required on an average fourteen and one-half minutes for the temperature to reach 209 degrees F., which is practically the maximum which can be attained under the conditions. When the olive was placed in cold water and the bath heated rapidly under conditions similar to home canning, the average time required to reach 209 degrees F. was 29 minutes. The former experiment represents a more favorable condition for heat penetration than prevails in factory operations, and the latter probably the least favorable, but both show that in the ordinary process all parts of the olive do not reach the high temperature supposed to be produced by that of the bath for more than a few minutes.

At the University of California ripe olives have been canned without brine. After pickling, the olives have been placed in 3% brine for several days, then heated in the brine to about 180 degrees F. after which they are taken from the brine, put in the bottles or cans, sealed, and processed. No shrinking, wrinkling, softening, nor change in color is said to take place. By the elimination of the brine in the container, there results a saving in freight of 31.5% with cans and 16.6% with bottles.