In California the commercially prepared olives are practically all ripe,
only a very limited quantity of green ones being prepared. Since the
olives, even on the same tree, ripen at various periods, three pickings
are made during the season, when olives well colored and of an equal
degree of ripeness are taken. In excessively ripe olives, the skin
toughens, and the fruit is difficult to pickle. The trees are pruned so
as to keep them low enough to be reached by the harvesters on step
ladders, in order that all picking may be done by hand. The picked fruit
is taken to a central point to be filled into boxes or barrels, for
transportation to the factory. For the best grades of olives, particular
care is taken during this part of the work to avoid bruising the fruit,
which is picked into canvas bags, pails, etc., then poured into barrels
partly filled with water, so that the water will furnish a cushion for
the fruit. The olives are transported to the factory in these barrels.
These precautions are taken as bruised spots soften and become black,
and the resulting processed fruit will not be of first quality. Many
[Illustration: Sorting Olives for Size by Machine]
growers deliver fruit dry in lug boxes, but bruising and crushing are
liable to occur during transportation. The fruit is delivered into a
hopper filled with water, then from the hopper into boxes where the
fruit is drained. The fruit is delivered in the factory to be first
sorted which is done on a moving belt, and here all stems and defective
fruit are removed as the fruit is carried slowly past the workers who
sit or stand on either side. In some factories the sorting is done after
the fruit is pickled, but is much more difficult due to the change in
color
[Illustration: Sorting Olives for Quality by Hand]
through the action of the lye and of oxidation. The fruit is next passed
to the grader, which separates the various sizes. From the grader the
three largest sizes are each delivered to a moving belt to be sorted for
color, degree of ripeness, and culls, as the curing must be modified to
suit the particular degree of ripeness, a crisp firm olive requiring a
heavier treatment than does a riper, softer-textured one. The olives as
sorted, are passed to small side belts, which thus deliver fruit uniform
in size and color to the receiving boxes. Great care is taken in the
sorting of olives, different varieties are not mixed, nor even fruit of
the same variety but from different localities. In grading for size by
machine, 1/16 of an inch is the variation between each size and the
next; those less than 10/16 are removed to be used for other purposes.
When the minimum is due to the variety and not to stunting, the fruit
may be pickled, because aside from the larger proportion of pit, the
flavor is equal to that of the large fruit. Usually the smaller olives
were used for oil, but more recently are used for relishes and sauces.
The sizes upon which the different grades are made are based upon the
short diameter of the fruit, and have been adopted by the California
Olive Association:
Number Diam. in
Grade per lb. inches
Standard 120-135 10/16-11/16
Medium 105-120 11/16
Large 90-105 12/16
Extra Large 75-90 13/16
Mammoth 65-75 13.5/16
Giant 55-65 14/16
Jumbo 45-55 15/16
Colossal 35-45 16/16
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
1-1/2%. 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
[Illustration: Curing Vats]
to 12-1/2% 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.
The history of the olive and its method of preparation show that no
organisms pathogenic to man are normally present and that if such
organisms be associated with it in any way, it must be from the outside
and through local infection.
More care is required in processing at high temperatures, than at
boiling. A high internal pressure is developed inside the cans or jars,
due to the expansion of the contents and of the enclosed gases, which
has a tendency to loosen or blow off the covers. This tendency may be
overcome by applying air or water pressure on the outside of the cans or
jars to counteract that generated within. This is done while they are
inside the retort and by means of automatic pressure controllers. There
is no essential difference in the sterilizing and cooling of tin cans
and glass jars, both forms of containers are responsive to treatment
with high temperatures and both require proper care and handling. As
with pickled olives, however, glass jars permit the purchaser to see the
size and the condition of the fruit.
The canning of ripe olives in California was originated by F. T.
Bioletti, zymologist in the University of California, and came about
through an
[Illustration: Packing Olives in Jars]
investigation in 1889 on the spoiling of olives. When pickled olives
were held, the quality deteriorated in some of them, they softened
during the summer, and seldom remained in an edible condition for a
year. As a result of his experiments on methods of keeping, he found
that the olives could be sterilized in sealed containers and be kept in
edible condition indefinitely. The commercial application of the method
and the popularizing of the ripe olive is due to Mrs. Freda Ehmann, a
pioneer olive grower, who applied scientific methods, with marked
success, to both the development and canning of the olive.
The sustained scientific work along developmental and preserving lines
in this country, has been done mainly by Wickson, Bioletti, and Cruess
of the state university staff to whom great credit is due for the
advancement made. Many improvements have naturally been made by
manufacturers in the preparation of the ripe olive but are held by the
factories for their own use solely.
Recently Cruess has developed methods for treating the ripe olive with
aerated hot solutions which have permitted the preliminary treatments to
be done in 3 to 6 days, instead of as formerly in 3 to 6 weeks. The
methods promise to be of great economic value, and have been patented
for the benefit of the public.
The olives which are too small or misshapen to be used in the regular
pack are sometimes used for other purposes besides oil extraction in
which size and appearance are not factors. The flesh is ground and
seasoned and thus furnishes a mixture for relishes and sandwich filling,
or the flesh is mixed with pickled cucumbers, capers, pimiento, tomato,
etc., in various combinations for the same purposes or to flavor sauces.
The appetizing ways in which olives may be used alone or in combination,
and the attractive dishes which can be prepared from them are endless.
A preparation which has considerable vogue with lovers of ripe olives is
to take the olives from the brine some hours before using and cover
them with olive oil. This preparation may be further enhanced by rubbing
the dish before using, with a cut clove of garlic. The use of aromatics
in the preliminary preparation, then packing in oil, as done by the
Greeks, Italians, and Spaniards, with some of their best olives, produce
very fine products that are far ahead, in both flavor and food value, of
the ordinary preparations.
The olive, though used almost exclusively as a relish or appetizer in
this country, is a valuable food. This is true for both the green and
the ripe, the difference in the two not being so great as is frequently
claimed. The pickled green olive has supplanted the cucumber pickle to a
very considerable extent in the trade. The canned ripe olive is
distinctive and depends upon an entirely different quality for its
favor. As long as the present prices prevail, they can not be considered
on the basis of staples or in competition with many other foods in
furnishing nutritive elements.
The flesh of the American olive consists of about 80 per cent of the
fruit, and of this the solids average 38 per cent, oil 25 per cent, and
protein 1.2 per cent.
In spite of the fact that olives have been used as a food from time
immemorial, very little systematic analytic work seems to have been done
on the whole fruit in the various stages of maturity and in determining
the effect of the various treatments for the removal of the bitterness.
Much of the analytic work has been devoted to analyses of the oil and
to methods for determining adulteration. The methods followed in this
country and abroad are not the same and the results are therefore not
comparable. It seems strange that so old and so commercially important a
fruit has not been investigated to the minutest detail.
It is stated that the olive on reaching full size increases in weight
and oil content as it matures, the various stages being approximately
determined by the change in color from green to yellow, red, and finally
black. When, however, one finds analyses of typical fruit of one variety
and from the same place which show the flesh of the green olive to
contain 23.55 per cent; yellowish green, 20.37 per cent; red, 27.35 per
cent; and purple to black, 24.89 per cent oil, it discounts the color
value. Other available analyses show similar discrepancies between the
chemical composition and the color test as indicative of maturity.
Variation in composition occurs in the same variety of fruit grown in
different places as well as in the different varieties and, as with
other fruits, one is dependent upon the skill of the packer in selecting
raw stock and in handling it in the process of manufacture, for the
quality of the article received. It is only natural to expect that a
product containing so much oil and subjected to the action of lye, might
be greatly changed during its preparation. The data available, however,
does not sustain this premise, but shows that very little change
actually takes place.