特级初榨橄榄油 Extra virgin Olive Oil

Florence, May 2001Extra Virgin Olive Oil: techniques and technology for a product of high qualityAlfa Laval SpAOlive oil ItalyDr Lamberto BaccioniNine calories per gramThis is the caloric contribution both of oils and fats: seeds oil, butter, olive oil, animal and vegetable fats.So, what distinguishes extra virgin olive oil from the other alimentary fats, for centuries so precious, both as food and as symbol of culture and rich source for the peoples of the Mediterranean coasts? Olive oil classificationThe oil extracted from the olives using a mechanical process (pressure or centrifugation) is classified using a chemical and organoleptic analysis:- extra virgin- virgin- lampante (in the past used for oil lamps)The lampante oil that is not fit for direct consumption is refined and after its mixing with virgin oil is reintroduced on the market under the commercial name of ”olive oil”.From the olive processing, after the mechanical extraction, the by-product is named olive husk (olive pulp with 3-5% of residual oil) from which the residual oil can be extracted with a solvent, such as esano.The extracted oil is refined and mixed with olive oil, to be marketed as “olive husk and olive oil”. While “olive oil” and “olive husk and olive oil” are used in industrial preparations and for culinary uses, especially for frying, the extra virgin olive oil is in particular used to be consumed directly, uncooked.So it is evident that the organoleptic features play an important role.Organoleptic featuresThe fruity smell, the tomato or artichoke taste, the typical bitterness of the oil produced with already partially green fresh olives, the spiciness of some varieties, like Frantoio: all these aspects satisfy the quality demands of the most exigent consumers.In these taste the consumer compares profiles with the organoleptic models they have in mind.The organoleptic profile is completed from the nutritional value of the extra virgin olive oil due to the minor components, such as the antioxidants, vitamins, the fatty acids and the absence of cholesterol. The affirmation of the Mediterranean Diet, as a correct model of alimentation, proves the final success of the extra virgin olive oil as the best condiment.Production and consumption of olive oil90% of olive oil is produced and consumed in the Mediterranean countries.The larger producer is Spain, with 650,000 - 950,000 tons/year, Italy is at the 2nd place with 500,000 - 600,000 tons/year and 3rd is Greece, with 350,000 - 450,000 tons/year.Italy is, however, at the first place both for the consumption, with 500,000 - 600,000 tons per year, and for the exportation, with around 150,000 - 200,000 tons per year.Italian production is not, however, sufficient for our needs, with around 150,000 - 200,000 tons per year of disparity.Recently the consumption trend is positive for extra virgin olive oil, while the olive oil consumption is decreasing, symptom of the consumers’ evolution towards better quality products under the organoleptic and nutritional point of view.The evolution was surprising in certain non producing countries, in particular in the USA, where in 14 years the consumption has grown from 20,000 to 160,000 tons per annum, and in Japan with more than 60,000 ton per year of extra virgin olive oil consumedThe production is evolving too, not only in quantity but also in quality.New producing countries such as Australia, Argentina, Mexico, California, have appeared.Other countries, even though traditional producers, have always had a limited role.They have been involved in a quantitative development process, but, moreover, a qualitative one, obtaining surprising results.Amongst these: Tunisia, Turkey, Syria and Morocco in the front line, and together they represent productive dimensions similar to those of Italy.The antique tradition, the climatic variability, and the numerous varieties&cultivars are the causes of the huge difference in the oils characteristics on the market.Huge commercialisation Companies, which drive the international market, with an affirmed competence, select and mix different oils from different countries to give consumers a satisfying product and reproduce the organoleptic model so much familiar and appreciated.Quality oil: IGP and DOPToday, as it has happened for the wine in the last 20 years, thanks to the producers’ direct presence, on the end-consumers market, with the qualified finished product, as oils of a protected origin (D.O.P.) and of a protected geographic indication (I.G.P), it is possible for the consumers to choose high quality extra-virgin olive oil, organoleptically different, according to the area of production. How to educate the consumers to choose extra virgin oil ?Probably quite soon, oil list, like wine list, will appear on restaurants’ tables.At least a small selection of oils, in their bottles with their labels, so that everyone can choose the oil accordingly to the dish and organoleptic difference: delicate oils with a soft almond taste, like the typical ligurian oil from “Taggiasca” olives, for fish; or bitter oils, fruity, with a typical spice of the Tucson olive oil, for vegetable soup; or otherwise tomato scented oil, delicately bitter, from western Sicily, from the “Nocellara del Belice “ variety, used on uncooked vegetables.The technology of oil extractionFor good quality production, the olives must be hands picked from the plant, otherwise with shakers and nets to avoid contact with the soil.From the nets, olives are transferred in plastic containers having a capacity from 30 to 300 Kg.The containers are then transported within 1 or 2 days to the oil mill, where, within 24 hours, the olives must be processed.The necessary ambient for the olives’ conservation, before the processing, is a fresh and aired place, to avoid the fermentation that causes overheating of the oil.The technology must help the Miller to respect and emphasise the nutritional and organoleptic characteristics of extra virgin olive oil.Until 40 years ago, for more than 5000 years, the oil extraction from olives was done pressing the paste obtained with stone mills.Nowadays, 70% of oil is produced thanks to modern machinery that has been by Alfa Laval introduced in 1962.In the modern process the working condition are controlled by the operator, especially the holding times and temperatures during the malaxing step.Very important are the hygienic conditions: every part, which is in contact with the product, is in stainless steel and is washable.This help to avoid taste alterations, typical of the pressing machines and caused by olive paste’s residual products’ fermentation, especially in the mixing mill and in the “fiscoli” (fibre disks on which the paste is stratified for pressing).The centrifugal machinery made a remarkable improvement on working conditions and, having a large capacity, help the reduction of working times economically.This allows the olives to be processed in their optimal maturation period (which lasts 30 - 45 days). At present the average capacity of the oil plant is growing in every country even if in different ways from place to place.In Spain the average size of a typical line is 100 – 150 tons of olives per day and many of the oil mills have more than one line.In Italy the average size of a typical line is 40 – 60 ton per day and the majority of the oil mills have only one line.The Oil MillsIn Italy, where there are around 6000 oil mills which process 2,5 million tons of olives, the oil mills’ average yearly output oscillates from 1000 tons for the 1200 oil mills of Puglia (40-45% of Italy’s potential ), to 400 tons for the 300 Tuscany’s oil mills ( 6% of the Italian production ).The average production of a typical working line is around 2000-2500 kg of olives per hour. Usually, in Italy, oil producers work olives on behalf of producers, that is the batch processing. Olive producers pay the oil mill’s owner according to the quantity of treated olives and the price is around 75 – 100 EUR per ton of olives.In Spain, instead, there are around 3000 oil mills that process, on average, 4 - 5 million tons of olives per year.Obviously the Spanish oil mills have a larger output than the Italian ones (4 times) with lower production cost for olives’ producers (farmers).Often the machinery has several production lines with a single capacity of over 5000 kg of olives per hour.In Spain the olives are industrially processed: they are brought to the oil mills and after the heap they are processed without being subdivided.Such a system restrains prices and supports the large-scale production of oil of a homogeneous quality, which effectively answers the bottling and marketing demands of largest trade companies.A typical example is Andalusia, where is produced around 60% of Spanish oil, mainly with the Picual variety, with a characteristic eucalyptus taste and with the Hojie Blanca or Arbechina.The extraction machineryThe extraction process is divided in different steps.Each relies on specific machines which, lined up, give a continuous and efficient process.The first step is represented by the defoliation and washing with water.The aim of this stage is to remove the stones, earth and leaves.The rinsed olives, washed with clean water on the washing machine, are fed with screw elevator in a mechanical crasher.The second step is the crushing of olives.To consent the best performance, according to the olives’ characteristics, Alfa Laval gives as an alternative to the stone mill, still used, four different types of crashers: toothed disk, hammer, roller and cone.Each one has different characteristics and has merits and weaknesses that each oil producer has to evaluate to make the right choice according to what he wishes to obtain.In summary, we can classify the different crashers:1. Stone millThey give a traditional image, very much appreciated in some traditional areas, even dough it gives hygienic problems.They are very large and expensive; they have a capacity of 800-1800 kg of olives per hour.They work crushing, with a limited effect of breakage on the skin, so that the oil will be colourless and bitterness.2. Roller mill with toothed finisherIt has a more energetic action than the stone mill machine; thus the result is slightly greener and bitterer oil, with a capacity of 1800 - 2200 kg of olives per hour.It takes up a less space than the stone mill machines and ensures better hygiene.3. Cone crusherIt is made up of a fixed cone and a rotating internal one (400 rpm), both toothed, and skinning each other they crush the olives, breaking pulp and stones but without damaging large parts of the skin.It gives a lightly coloured and bitterness taste.The capacity of this kind of crusher is around 1500-2000 kg of olives per hour.The breaking organs are made of a very hard material and are therefore particularly expensive.4. Toothed disk crushersThese are the exclusive Alfa Laval products aimed at satisfying the expectations of who requires big productive capacity, with an efficient extraction of colouring and bitter substances, without the problems caused by the emulsion and overheating.It is made up of a fixed disk with pegs or teeth, which meets with another disk with staggered teeth, which rolls at about 1400 rpm.Olives enter trough the centre and radially crossing the disks are crushed in minute pieces.The distance between the two disks can be regulated to obtain the desired dimensions of broken pieces of olives.5. Hammer mill crushersThey are made up of a circular cage, in which a cross turns at 2900 rpm.At the extremities of the cross there are plates made of a hard material, which crush the olives against the net itself, until the olives cross the net are reduced in paste form.The grill holes can be varied from 5 to 7 mm to have a different granulometry according to the sort of olives.This is the crusher with the maximum capacity and lowest cost.For this reason they are the most popular, especially in these areas in which the productive capacity is the most important aspect.Their limit is linked to the breaking force, which can cause emulsion and paste heating risks.In this case the direct result would be the production of bitter oils.The third step is the malaxing the paste of crushed olives.The crashed paste is picked up in one or more ( until 10 sections in parallel ) double walled ( jacket) horizontal open tank, equipped with slow mixer, where warm water circulates at 35°C, in the jacket. The total volume of the containers, called “Malaxing machine”, is calculated to give a holding time of around 40-60 minutes, so that the paste can reach at least 30°C.During this period the paste is mixed to consent the oil drops’ release.Those drops are wrapped up by lipoprotein membranes, contained in the olive cells.The minute oil drops, due to coalescence, become larger, and thanks to the centrifugal force they become separable in the decanter.Malaxing machines are made in stainless steel for hygienic reasons and the rotary reels meet, at about 5 mm distance, the walls of the malaxing machines to continuously remove the paste, guaranteeing the best distribution of temperatures, around the average value selected by the regulation system.The separation machineryOnce the paste is ready, it is fed by a mono-pump into decanter where the division of the oil from the water and olive husk takes place.A small amount of warm water is added to the olives paste (from 10 to 20% according to the olives’ weight), to improve the paste’s fluidity inside the decanter in order to obtain an efficient separation between the three stages (water-oil-olive husk), this guaranteeing the extraction result of the productive capacity.Alfa Laval has recently introduced the new VDP decanters with a steep cone with a conveyor’s differential speed control system (VS + ECB).In this new generation of decanters, whose capacities vary from 1200 kg/hr to 7000 kg/hr, thanks to the ARA regulation and the conveyors’ differential speed, the customer can obtain excellent performances with the possibility of regulation and adaptation of the performances according to the olives’ characteristics.Alfa Laval’s exclusive reduced water consumption, in the ARA system, allows the operator to control the characteristics of the oil: varying the oil/water ratio of dilution, it is possible to influence the taste of the oil and its resistance to oxidation.Reducing the amount of water one obtains oil that is richer in phenols substances and therefore more bitter and stable.The oil extracted from the decanter is sent to a vertical separator, in which the remaining water and impurities are separated to have clean oil, to be directly consumed, after a filtration by gravity on hydrophilic cotton, for dehumidification.Oil conservationThe lack of emulsified water in the oil prevents the proliferation of micro-organism, that change the taste of the oil, allowing a shelf life of 18-24 months, if it is conserved in the dark, out of contact with oxygen and at around 15-20°C.The bottles made of a dark glass and small capacities prove to be the best solution.Kept in a dark, cool ambient they allow to be consumed quickly, so that one can appreciate the smell and taste of a product that carries with it the charm of its millenary history.To enjoy fragrant oil from the oil mill, even in summer, try freezing in autumn small bottles (250 ml, not full) at – 20°C; once defrosted it lasts not for long, but what a surprising delight it is on a fresh salad!。