Varieties and Harvesting of Olives!
There are 5 main varieties of olives grown in bearing hectarage (acreage) in California. The Mission olive, formerly the main olive of the industry has, during the past 25 years or so, declined to last place in importance because of its tendency to produce small fruits and its propensity for late maturity.
The main varieties grown now, in commercial importance, are the Manzanilla, Sevillano, and Ascolano in the order named. Lesser varieties also are grown, including the Barouni which now is seldom used for canned ripe olives but is utilized in all sizes for Spanish-type olive production.
It is also sold on the fresh-produce market for home pickling as are some of the Northern California Sevillano fruits and other varieties, at the discretion of the fresh-market shippers. All except the Mission olive are of foreign origin- the Manzanilla and Sevillano olives were imported from Spain, the Ascolano from Italy, and the Barouni from Tunisia.
Each variety is distinctive in size, shape, and general utility. The Sevillano olives are the largest, followed in order by the Ascolano, Barouni, Manzanilla, and Mission varieties. The Manzanilla variety most nearly approaches the requirements of an all-purpose olive, since it may be used for the production of California ripe olives, green fermented olives, or olive oil. The other varieties have characteristics which limit their usefulness in one way or another.
Most of the olives used for ripe or green pickling are harvested starting between the middle or latter part of September and ending at about Thanksgiving time (late November) if the crop is large, The time will depend on the variety of fruit, the locality, the growing season, climatic conditions, and other factors. A sharp frost means termination of picking olives for processing. Frosted olives generally are salvaged for oil production. It is desirable to remove all, or nearly all, of the fruits produced in a season to help ensure a good set of fruit the following year.
Because canned black-and-green-ripe olives are the main products of the California olive industry, harvesting practices favor the selection of fruit most desirable for production of these two commodities. Therefore, when the majority of the fruit in an orchard has reached the desired maturity, the harvest is started and continued until all, or nearly all, of the olives have been gathered.
Mature (tree-ripened) olives do not have the final dark purple to jet black color at the time of harvest for pickling, but are at the color turning stage, from green to straw yellow or, at most, light cherry red. More highly colored fruit may be overripe. Over ripe fruit, which is highly colored, generally deteriorates during the lye pickling process, and consequently is diverted to oil production, or if the texture still is quite firm, may be used for the preparation of the Greek-type brine-cured or salt-cured olive specialties.
California canned black-ripe olives (generally uniformly black in color after canning) are made from fruit ranging in color from green to not more than cherry red at harvest. The California green-ripe or “home-cured” olives (yellowish-green to light greenish-brown, frequently mottled color after canning) are made from fresh olives having a green to not more than cherry red color. California fermented green olives (Sicilian- and Spanish- types) are produced from fruits ranging from green to straw yellow in color.
Harvesting, formerly all done by hand, is slowly becoming mechanized Machine tree-shakers are being used in newer groves where the trees have been pruned in a fashion to promote removal of olives by shaking. However, in old groves the trees were pruned in such a manner that machine removal was impractical because of failure to remove enough fruit, or the trees were infirm and there was much damage due to limb breakage.
Studies also have been made with chemical spray treatment to facilitate machine harvest of the olives. Unfortunately, fresh olives are quite easily bruised and the amount of bruising is accentuated with mechanical harvesting, but fortunately, the bruises do not affect the appearance of the processed black-ripe olives or Greek-type olives. However the bruised spots do persist in the processed green-ripe and the fermented green Sicilian-type and Spanish-type olives.
In the interest of economy, hand labor is reduced as much as possible. Harvested fruit whether hand- or machine-harvested is placed in bulk-bins for transportation to the pickling plants by truck or other mechanized equipment. These bins, widely used in the food industry, are designed to be handled by forklift trucks. They are approximately 4 ft2 and 2 ft deep, have a 2-port pallet entry, and, if filled completely, hold 453.6 kg (1000 lb) or more of fruit.
Sweating of the fruits held in bins can be a problem. To avoid possible fruit damage caused by sweating, the olives should be put through the various plant operations in as short a time as possible; preferably all bins of olives should have been delivered to the plant, dumped onto the transfer lines, put through the destemmer, and sorted and size graded in not more than 24 hr.
In years of high yields of olives, some packers store fruit under refrigeration for varying lengths of time. The olives are cold-susceptible so they should not be stored below 7.2°C (45°F) in order to avoid an undesirable taste in the processed fruit. Freshly harvested olives can be held under refrigeration without undue mold development if the refrigerated storage is properly operated. On longer holding, molding becomes a problem in the center of the mass of olives, and the loss increases with the increase in storage time.
Olives can be held in light brine (5% NaCl) under refrigeration for a period of at least 6 months without loss resulting from microbial activity if the containers are anaerobic or nearly airtight at the least.
Once the harvested olives have been destemmed, sorted, and size-graded, they ate ready to be processed, stored in salt brine for future processing, or made into fermented Sicilian- or Spanish-type green olives.