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different mechanisms, resulting in a mixture of pheophy-tins and pheophorbides in the final product (85). In relation to the carotenoid fraction, only ^-carotene and lutein are resistant. Phytofluene and ¿'-carotene disappear, and vio-laxanthin, luetoxanthin, and neoxanthin give rise to their isomers auroxanthin and neochrome. The degradation taking place, however, does not give rise to uncolored final products with pigmentation loss, and the total balance of pigments remains constant with time.

In the case of Greek-style natural black olives in brine, prepared without a previous lye treatment, the concentration of soluble sugars remains relatively high (SO.3%) even after long storage in brine. The same happens to oleuropein and tannins, as a consequence of a very slow fermentation process. For that reason, sensory properties of this final product are quite different from those of the other two types and are also very appreciated by the consumer.

The main difference between Californian-style pickled black olives in brine and those previously described is due to the oxidation in an alkaline medium. If storage in brine before processing is used, the characteristics of the fruit at that stage are similar to those processed as natural black olives in brine, with only the difference in color due to the stage of maturity at which they are harvested. As a result of the processing conditions, tannin and oleuropein content, as well as total acidity of the final product, are very low, and it must be sterilized by heat as a consequence of the relatively high pH value.

In summary, the changes that occur during processing may be divided into three groups: (1) compounds that are simply lost during the different stages of the process; (2) compounds that are transformed by simple chemical reaction or by the action of enzymes originally present in the fruit or produced by microorganisms; and (3) compounds produced during fermentation by different microorganisms. Table 7, Table 8 and Table 9 show the main changes produced in the three types of processing mentioned in this article.

Main Industrial Processes

Spanish-Style Pickled Green Olives in Brine. Within the green-olive type, which accounts for ca. 42% of the world production of table olives, the most important commercial preparation is that of Spanish- or Sevillan-style, which in turn accounts for the highest percentage of the international trade. They generally may be preserved as is; however, if the fermentation is only partial, they keep the denomination pickled green olives in brine but do not enter within the Spanish style. In that case, their further preservation, at a pH value within the limits specified in that standard, may be ensured by (1) sterilization or pasteurization, (2) the addition of preserving agents, (3) refrigeration, or (4) inert gas, without brine.

Other green olives are prepared without a prior alkaline treatment and are placed directly into the brine, either to undergo a natural fermentation or to be preserved by any of the procedures mentioned earlier. In those cases, they keep the denomination green olives and the word pickled disappears. Their commercial importance is minor, although final products of excellent quality may be obtained by those procedures. Table 7 shows the different phases for the processing of Spanish-style pickled green olives in brine.

The fruits are picked when their color is still green or yellowish green and are harvested by hand, although numerous attempts have been made to harvest them mechanically. Tree shakers have not been well accepted yet because of the damage they cause to the trees and fruits.

Fresh fruits are then transported to the factory either in crates of perforated plastic material that allow access of air, with a 20 to 25-kg capacity, or in bins with perforated mesh walls of higher capacity. The fruits remain in their containers for a period varying from several hours to 3 or 4 days, depending on the variety. After sorting and an optional size grading, the fruits proceed to the lye treatment.

Fruits are treated with a diluted solution of sodium hydroxide to eliminate the greater part of the bitter glucoside oleuropein. In this treatment, the lye penetrates the pulp to a depth of two-thirds to three-fourths the distance between the skin and the stone. The lye concentration used varies generally between 1.3 and 2.6% (wt/vol), depending on temperature, variety, and stage of maturity of the fruits,

Table 7. Spanish-Style Pickled Green Olives in Brine: Scheme of the Process and Compositional Changes

Phases

Operations

Flow chart

Changes in composition

Prior phase

None

Fresh olives

Harvesting

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