Olive Oil Production

22-06-2023 11:52

In its simplest form, production is a three-step process; Forming an olive paste by blasting/smashing/crushing, separating water and oil from solid material by applying pressure or centrifugation to the paste, separating oil and water in the final stage.

History

This process has remained virtually unchanged for thousands of years, with no chemical treatment at any stage. Archaeologists, who found bronze age pits and forging tools, think that the first mechanized agricultural tool in human history was probably designed for olive oil production.

The simplest method of making olive paste is pounding it in a mortar. Then, by skipping the second step, in other words, by simply pouring hot water on it without even applying pressure (separation, hot water facilitates the separation of oil from water) olive oil can be obtained. Since oil is lighter than water, it will rise above hot water. This method is described in the Bible as "washed oil", describing how to produce small amounts of olive oil for religious purposes.

The process defined as "foot oil" in the Anatolian geography today is nothing but the use of human weight in the pressing stage, the olive paste consisting of crushed and blown olives put in a sack is crushed with the foot, the purpose is to separate the olive oil and olive juice from the solid elements in the dough. Olive juice and olive oil leaking from the pores of the sack are collected in a bowl, and the oil that rises above the water is taken with ladles. It may still be used in Corsica and in our country. It has also been found that this practice was used in winemaking in ancient Egypt to separate the grape juice from the skin and seeds.

In the process of crushing olives, semi-cylindrical stone mills, which are managed by human power, begin to be used over time. This method was followed by cylindrical stone mills rotating around their axis in the Roman period (348 BC). After this invention called "Mola olearia" (olive mill), the "blood mill" (trapetum), the oldest example of which was found in Pompeii, appeared on the stage of history. The reason why this device is called “blood mill” is because it works with animal power.

The simplest approach to performing the pressing or pressing process is to put weights on the compressed dough. Archaeological studies have found many stones that resemble a hollow stone bowl, in which bags of olives were placed. There are many archaeological findings of this kind, especially from the Roman period, when olive oil production and demand for olive oil increased.

The use of stones for the pressure application process is as old as the use of feet. The right-angled millstone used for olive oil production is considered one of the first agricultural tools in the history of agriculture, archaeological findings go back to the 4th century BC.

In ancient Egypt, olive paste was first put in sacks and squeezed by two people, then it was started to be squeezed with the help of wedges. Wedge presses were later followed by wood presses. This method was followed by squeezing the olive paste inside the bags in a vise-like mechanism. Then, the worm screw or “Archimedes Screw”, which was used for the first time in the Roman period and used to control the power in the presses, came into use.

At the beginning of the 19th century, with the industrial revolution and the development of technology, the method of applying pressure began to be made with hydraulic press machines.

In our age, hydraulic press machines are still used, but machine units that enable to obtain olive oil by centrifugal force (centrifuge) without applying any press to the olive paste have become widespread.

Olive Oil Production Today

The modern process consists of the following steps;

1. Harvesting, Sorting, Washing.

2. Crushing and Crushing the Olive.

3. Kneading (Malaksation).

4. Separation of Oil.

The separated oil is rested and stored in steel tanks.

Step 1: Harvest, Sorting, Washing

Olives should be processed as soon as possible after harvest. Because if the olive is kept waiting, fermentation (rottenness) will start, which will cause the quality of the oil to decrease.

Depending on the harvesting method, about 5% of the harvested olive consists of foreign matter/stone, soil, thin olive branch and olive leaves. If foreign materials are not sufficiently removed, the acid rate, color, smell and aroma of the oil obtained at the end of the process will be adversely affected. After the leaves are separated, washing is done with water.

It is normal to some extent that some leaves mix with the harvested product during harvest. It has been shown that fresh olive leaves do not have a negative effect on the chemical content and quality of the oil, it is believed that it can also give a pleasant smell to the oil obtained, but if the rate of mixed leaves is high, the color of olive oil turns green and its aroma becomes bitter. This is especially likely in systems where metal breakers are used.

Step 2: Crushing and Crushing the Olive

crushing process; It is the physical damage to the components in the olive, so that the oil particles in the micro-molecular structure combine, become more suitable for the solid-liquid phase separation process and acquire a fluid form. In this step, stone mills made of granite are used in old and intermittent systems, and metal crushers are used in continuous systems due to their suitability for automation. The temperature of the olive paste as a result of the kinetic energy generated during the process; It increases by 4-5 °C when stone mills are used, and 13 -15 °C when metal crushers are used. Both applications used at this stage do not affect the measurable quality characteristics of the oil. But the use of metal crushers; is to increase the total phenolic content of the oil, accordingly the resistance of the oil to oxidation increases, thus providing a positive effect on quality and shelf life.

Step 3: Kneading (Malaksation)

In this step, the olive paste is tried to be homogenized in a closed system, the paste obtained by the combination of oil molecules forming micro spherical droplets is prepared for the next liquid-solid phase separation process. The oil droplets combine to form a continuous phase and form large drops, and the oil-water mixture is tried to be separated and the oil becomes free. At this stage, two important factors affecting the quality of the oil are time and temperature, kneading should not be done for more than 20 minutes if stone mills are used, 90 minutes if metal crushers are used, and care should be taken not to increase the temperature above 25 degrees. At this stage, the efficiency of the liquid-solid separation process is tried to be increased with the Pulsed Electric Field (PEF) technique (the application of electricity in times ranging from nanoseconds to microseconds; electroplasmolysis).

Step 4: Separation of Oil

It is the process of separating the fat in the dough from the solid components and water. While pressing is done in classical systems, centrifugation and perlocation systems are applied in modern systems. The combined use of centrifugation and perlocation is also possible.

The negative aspects of the classical pressing method are that the equipment used is very bulky, the need for a lot of labor, the interruption of the production process, the difficulty of cleaning the discs woven from the used jute plant fibers, and the possibility of easily contaminating the discs with foreign substances and microorganisms.

Principle of centrifugation process; It is based on the separation of the liquid phase (oil and black water) in the olive paste from the solid phase with the help of high speed rotating decanter technology. The decanter is a machine that performs the horizontal centrifuge function used for the separation of solid and liquid mixtures with different specific gravity. The advantages of this method are that the technology in this method is not cumbersome, is suitable for automation, requires less interruptions, and requires less labor. 2, 3 or 2.5 phase systems are available. The total polyphenol content of the oil obtained from two-phase systems in which less dilution water is used and accordingly its resistance to the negative effects of oxygen is higher.

The selective filtration (sinolea-percolation system) method is based on the principle that the surface of the steel plate immersed in the olive paste is covered with the oil phase due to the surface tension difference between the liquid phases (oil and black water). However, the oil yield is low, approximately 10% of the oil remains in the pomace, which contains some oil, water and solid residues after the olive is pressed. Therefore, if it is to be used, it is applied in combination with the centrifugation system.

Storage/Storage of Olive Oil

After the oil separation process is completed, it is rested and stored in steel tanks to be kept away from air, heat and light in order to protect it from the negative effects of oxygen in the air. The most suitable materials used to preserve olive oil are glass and stainless chrome nickel steel tanks, due to their non-interacting properties with oil. Thus, the quality of the olive oil obtained is not adversely affected. Warehouses with steel tanks should be climatic and temperature controlled spaces. If the tank is not filled to the top level, nitrogen gas is injected between the cap and the level where the oil reaches, preventing the oil from contacting with oxygen.

The chlorophyll in the content of olive oil is the reason why the oil is sensitive to light. For this reason, it is used in colored glass bottles, colored glass carboys, porcelain or steel containers and lacquered inner surfaces (in order to prevent the material from which the box is produced from contaminating the food and the product inside causing corrosion on the inner surface of the box), it is used in cans. should be stored.

The mouth of the storage container should be tightly closed in order to prevent the odors in the environment from permeating the oil. A bottle that is tightly closed and never opened can be stored in a suitable environment for up to two years. If it is an opened bottle, it should be consumed within two months. If it comes into contact with air for a long time with its mouth open, it starts to deteriorate and the acid rate increases. It is not recommended to put olive oil in the refrigerator.

Oils produced from early harvested olives may be slightly cloudy, however, they are the most preferred products due to their unique aroma and micronutrients. The color of the oil is not an indicator of quality, it can vary from bright yellow to raw green depending on the type of olive and the time of harvest.

Natural olive oil starts to freeze below 5 °C and evaporates above 200 °C. The optimum temperature for storage is 14-15 °C.

Compiled by: Uğur Saraçoğlu (ugisaracoglu@yahoo.com.tr)

Resources:

1. Innovations in Olive Oil Production Technology, Prof. Dr. Aytaç Sargın Gümüşkesen, Ege University Engineering Faculty, Food Engineering Department, Power Point Presentation, 2010.

2. World olive encyclopedia; International Olive Council; Fausso Luchetti, 1997.

3. Olive oil; Fahrettin Göğüş, Mücahit Taha Özkaya, Semih Ötleş, Eflatun Publishing House, 2009.

4th Izmir Olive Symposium; In Search of the Immortal Tree/Don't Touch My Olive, 2-3 September 2015.

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