9,4 Mb - formato pdf - Enoteca Regionale

PROCESSING AND CONSERVATION METHODS
The “Spanish method” processing cycle is as follows:
- debittering by soaking in a dilute caustic soda solution;
- fermentation in brine.
DEBITTERING aims to solubilize the bitter element in the olives, oleuropein, a glycosidetype
substance. Debittering is achieved with dilute solutions of caustic soda (NaOH) to
hydrolyse oleuropein to glucose, enolic acid and dihydroxyphenylethanol, compounds that
later removed by rinsing. Concentrations used may oscillate from 2 to 2.2%, depending
on ambient temperature, variety and ripeness of the fruit. During the alkaline treatment,
the olives are constantly immersed in the aqueous solution, since they turn black if left
in the air and debittering would be partial, with negative effects on product edibility;
moreover, the soda must be changed regularly in order to keep the concentration constant.
The debittering treatment is complete when the soda solution has penetrated 2/3-3/4 of
the flesh of the olives, a limit not be exceeded if the quality and quantity ratio equilibrium
of the fruit is to be safeguarded for the product in pursuing fermentation which may
effects the end results of this process negatively if they develop incorrectly.
This alkaline treatment usually takes 7-10 hours, depending mainly on the concentration
of the soda and the temperature.
WASHES: the olives are washed by leaving them in water that is changed a regular basis
until the pH is found to be about 7-7.5. During these operations it is important to avoid
too much ventilation of the mass and exposing the fruit to the air, which will cause damaging
oxidising browning that depreciates the commercial value of the end product.
Three rinses are generally performed, requiring a total time of 24-27 hours.
The rinsing water can be changed at flexible intervals without adverse effects on the end
result, nevertheless, when choosing and scheduling washes a series of technical factors
must be considered, inherent to the specific characteristics of each variety and the concentration
of soda used in the olive debittering phrase, since the flavour of the finished
product will depend on this.
FERMENTATION: after the olives have been washed they must be left to soak in a saline
solution with the NaCI concentration at 7-8%, prepared with water that has limited alkaline-earth
metals (Ca, Mg, Ba) content, which may create abnormal flavour in the fruit.
A salt balance is generally achieved between the olives and the brine after 7-12 days,
and periodic additions of salt (NaCI) are necessary since the concentration of brine will
decrease by 40-50% compared to the initial quantity. The olive fermenting process comprises
three stages that may be distinguished by the different microbic composition of
brine for each one: 1) stage one, typified by the development of Gram-negative Coli-
iformes-type and Gram-positive germs, with a brine pH that passes from the initial value
of about 8 to 5-5.6 in about 3-5 days; 2) stage two, characterized by the development
of lactic bacteria and yeasts with a brine pH that falls to 4.5-5 in 10-15 days, with a progressive
decrease of negative germs; 3) stage three characterized by a massive development
of lactobacilli, onset of Gram-negative bacteria and brine pH of about 4 after 20-30
days.
The process is complete after 25-40 days, when the olives are straw yellow-green in
colour, with firm flesh and a pleasant, rather sharp flavour of lactic acid, and they are
then ready to be sold, whole or pitted.
STORAGE: olives prepared in this way can be kept naturally if the solution pH is about 4
and the brine never less than 7-8%, otherwise pasteurization is recommended.
Materials, specific equipment used in preparation and conditioning: modern technologies
are sensitive to quality and cost reduction issues so the entire transformation
process is performed in large containers. Here the olives, which have been handpicked to
avoid irreversible lesions or damage that will depreciate the product, stripped of leaves
and, preferably a graded size, are treated applying the strictest control of process factors
that may condition fermentation, so as to guarantee standardised production batches.
PLANTS AND SYSTEMS: 1. water; 2. electrical system: must be compliant with the most
recent workplace safety regulations; 3. lighting: must provide a level of artificial lighting
that allows working and inspection operations to be performed correctly.
Minimum line equipment shall include: hopper for loading olives – defoliator and waste
separator – forklift – conveyor belt for moving olives – sorting bench – grader with mobile
diverging chains – water tanks - concentrated soda tanks – tanks for preparing soda
and brine solutions etc. – PVC containers for storing graded olives – fermentation vessels
– containers for storing fermentation brine.
Description of processing and conservation premises: the premises chosen for processing
plants must have adequate road, electricity and water networks for its needs.
In particular, there must be a plentiful supply of water, bearing in mind that water consumption
for processing olives is estimated to be seven times the amount of the end product.
The same sort of care is required to ensure the best disposal solution for waste waters.
The areas where the olives will be stored must be given careful consideration since
the fruit arrives at the plant in traditional stacked crates; storage must be such as to ensure
easy transfer of the crates to the processing line. The area that will house the fermentation
vessels must be about 8 metres in height. Lastly, it should be remembered that
the plant must have a basement section (for about half of the surface area of that enclosed
buildings), dedicated to the storage of olives being processed with special systems,
especially during hot weather.
NATURAL OR TRANSFORMED VEGETABLE PRODUCTS 219