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The production of quality virgin olive oils in an olive mill requires the fulfillment of four basic requirements:

  1. To have a quality fruit.
  2. Care for the fruit during cleaning, transport and storage in the yard.
  3. Control the conditions during extraction(milling, beating, centrifugation and clarification), as well as the subsequent storage conditions.
  4. Maintain all installations and, above all, machinery in an adequate clean condition.

As has been repeated many times, quality is a chain that can be broken by any of these four links, resulting in the production of oils of lower quality than potential. In our opinion, the requirement for cleanliness is not given due attention, which can lead to a loss of quality in the oils produced. However, before continuing with this analysis of olive oil mills with respect to cleanliness, we would like to point out that any general statement about this ‘current situation’ is incomplete, partial and, therefore, inaccurate. There are all kinds of situations regarding the cleaning of oil mills, so no generalization is correct.

Cleanliness in the design of oil mills

When considering the design of an oil mill, whether it is a small plant for the production of high-end oils or a large mill to process many millions of kilos of olives, cleanliness is generally not present during this design stage. The project developer and the engineering firm in charge of the project will devote many hours to the design of the facilities and the choice of the machinery for the yard, milling and cellar. The design and selection variables will be mainly the production capacity and price of the different alternatives. In some cases, the study of other minor issues, such as maintenance costs or energy consumption of some options versus others, will be considered. What will hardly be taken into account at the time of this design of installations and choice of machinery is their cleanliness.

The decisive questions will be, for example, how to optimize the milling capacity in the event of a massive influx of olives, or how to minimize the waiting time of the members during the unloading and weighing of the olives, or how to clean the facilities and the machinery. Generally no. However, both the design of the mill and the choice of machinery have an enormous influence on the ease, effectiveness and efficiency of subsequent cleaning tasks. On the other hand, when designing and building a new oil mill, it is very easy and economical to take certain measures that will greatly facilitate subsequent oil mill cleaning tasks. If they are not taken into account, it will be more difficult and costly to implement these measures later on.

And this is a fundamental issue:
an oil mill designed to be cleaned will be easy to clean.
On the other hand, an oil mill where cleaning has not been taken into account in its design will be more difficult to clean and less effective and efficient.

And is this really important? Let’s think that 100% of our raw material is going to circulate through a transport element that probably does not have the desired degree of cleanliness, coming into contact with olive residues, vegetation water and crushed mass that can carry ? days in decomposition…

This same reflection can be extrapolated to other elements and parts of the production process.

Another fundamental issue when designing an oil mill to facilitate its cleaning is to take into account the management of washing water. In a conventional processing line, as its cleaning has not been taken into account, it has not been foreseen how the washing water will be managed.

Cleanliness in the operation of oil mills

Regardless of the design and existing machinery, the cleaning of facilities and machinery must be a scheduled and systematic task. This need is already included in the regulations on General Hygiene Plans and Hazard Analysis and Critical Control Point Systems(HACCP), which must reflect the guidelines and procedures for cleaning olive oil mills.

In practice, the intense pace of campaign work means that cleaning tasks are generally carried out less frequently than would be desirable. On a day-to-day basis, the numerous functions and tasks that factory personnel must attend to prevent them from having the necessary time to clean the machinery. This situation is especially pronounced at times of maximum olive intake.

Often, the mill personnel(the mill, one should say) are not sufficiently aware of the importance of cleanliness in the quality of the oils obtained.

How are you going to stop to clean? Here is the question. Obviously, when hundreds of thousands of kilos of olives are coming in every day, you can’t stop to clean. But if you have the right tools and procedures, there is virtually no need to stop for cleaning.

You are probably thinking of a complete shutdown of production in order to clean up. This reflects another fairly frequent circumstance: cleaning when there is nothing else to do. Or when the weather decides; that is, when several consecutive days of rain occur.

Even at peak times, during continuous operation there are situations when a certain process step, or a specific machine, is not processing the corresponding material or product. At this time, the machine can be cleaned without interrupting the normal working rhythm. But for this to be possible it is necessary to have the factory ‘ready’.

Importance of cleanliness in oil quality

Throughout this article, the effect of cleanliness(actually, lack of cleanliness) on the quality of the oils produced has been taken for granted. But does cleanliness really have that much effect on quality? If a processing line is running continuously, does it really get dirty? Is it necessary to clean it so frequently?

Let’s consider the following scenario: while processing quality olives with clean machinery in mid-November, we have finished processing the olives that came in that day. When the olives are finished(at dawn), the machinery is simply turned off, without any cleaning work being done. The following day, in the afternoon, milling will begin again with fresh olives of the day, of the same quality as the previous day. The oil obtained on the second day is logically stored in the same tank as that of the previous day.

What happened during that brief downtime inside the machinery? Because the remains of olives, dough and oils have undergone oxidation, fermentation and alteration processes that cause a serious deterioration of their quality. When the process is restarted, with quality olives, the first fractions of olives, mass and oils ‘drag’ the deteriorated remains of the previous day, giving rise to an oil of very low quality. If this ‘head’ of the new batch of oil production is destined for the same tank as that of the previous day and that of the same day, the overall quality of that tank will probably have been spoiled and, although it may have been of the highest quality, it will have perceptible sensory defects. This situation can be classified as a ‘slight lack of cleanliness’.

At the beginning of the second day of milling, with quality olives(and a high fruitiness), there is a dragging of the remains of the previous day contained inside the machinery, giving rise to an oil with appreciable defects. When these residues have been totally expelled, the defect disappears and excellent quality oils are obtained.

Some readers may be thinking: okay, but as long as production is not stopped, there is no problem. Yes, there is a problem. During the continuous operation of the process, material debris is continuously generated in the hoppers, augers(very important), mills, dough mills, pipes, mixers, pumps, sieves, etc., which deteriorate rapidly. If they are not removed(by washing), they come into contact with the fresh material and are partially incorporated into it, contributing sensory defects to the resulting oils. Other chemical parameters, such as alkyl esters, may also be affected.

An oil processing line is ‘not a pipeline’. In a pipeline(e.g., dough), material deposits do not occur during “continuous” operation. But in a processing line there are numerous surfaces, partially filled containers, dead zones, nooks and crannies, elbows, inaccessible areas, low areas without purging, etc., that are difficult to access and clean. All these spots are ‘black spots’ where dirt accumulates and will negatively affect the quality of the oils.

By way of conclusion we can say that, in general, cleanliness should be more present when designing, constructing and operating oil production facilities and machinery. It is possible to glimpse that cleanliness is the next revolution knocking on the doors of the olive oil sector. This revolution requires putting cleanliness at the center of the game board as a strategy for improving oil quality. And this requires, indispensably and as a precondition, a change in the mentality of the managers and factory personnel.

From fadein we put in your hands suitable products for an efficient cleaning of oil mills, and our experience in solutions to improve the cleaning systems in oil mills.

For the correct degreasing and cleaning of an olive oil mill: crushing mill, mixer-decanter, centrifuges, tanks, hoppers, augers, screw conveyors, massagers, pipes. We have a special concentrated degreaser that can be diluted in water at 10%(1 liter of product for every 10 liters of water) for most uses. fadein-308-A. Providing effective cleaning of all elements.

In places where disinfection is required, use
would be a good solution.

We hope you find our recommendations useful. If you have any questions or suggestions for our next articles, you can write to us at
[email protected]
we will be glad to hear from you.

Bibliographic reference

  1. Effect of lack of cleanliness on the quality of the virgin oils obtained. José A. García Mesa, Araceli Sánchez Ortiz. EXPOLIVA’17 Scientific-Technical Symposium
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