{"id":98,"date":"2018-07-09T23:55:27","date_gmt":"2018-07-09T23:55:27","guid":{"rendered":"http:\/\/www.essentialoilmach.com\/blog\/?p=98"},"modified":"2019-12-16T09:17:08","modified_gmt":"2019-12-16T09:17:08","slug":"essential-oil-extraction-by-expression","status":"publish","type":"post","link":"https:\/\/www.essentialoilmach.com\/blog\/essential-oil-extraction-by-expression\/","title":{"rendered":"Essential Oil Extraction by Expression"},"content":{"rendered":"

Expression or cold pressing, as it is also known, is only used in the production of citrus
\npeel are crushed or broken to release the oil. One method that was practiced many years ago,
\nparticularly in Sicily (spugna method), commenced with halving the citrus fruit followed by pulp
\nremoval with the aid of sharpened spoon-knife (known as a rastrello). The oil was removed from
\nthe peel either by pressing the peel against a hard object of baked clay (concolina) which was
\nplaced under a large natural sponge or by bending the peel into the sponge. The oil emulsion
\nabsorbed by the sponge was removed by squeezing it into the concolina or some other container.
\nIt is reported that oil produced this way contains more of the fruit odor character than oil
\nproduced by any other method.
\nA second method known as equaling (or the scodella method), uses a shallow bowl of
\ncopper (or sometimes brass) with a hollow central tube; the equaling tool is similar in shape to a
\nshallow funnel. The bowl is equipped with brass points with blunt ends across which the whole
\ncitrus fruit is rolled by hand with some pressure until all of the oil glands have burst. The oil and
\naqueous cell contents are allowed to dribble down the hollow tube into a container from which
\nthe oil is separated by decantation.
\nObviously, hand pressing is impractical because it is an extremely slow process, e.g. on
\naverage only 2-4 lbs oil per day can be produced by a single person using one of these hand
\nmethods. As a result, over the years a number of machines have been designed to either crush the
\npeel of a citrus fruit or crush the whole fruit and then separate the oil from the juice.
\nPelatrice Process
\nIn the pelatrice process, citrus fruits are fed from a hopper into the abrasive shell of the
\nmachine. The fruits are rotated against the abrasive shell by a slow-moving Archimedian screw
\nwhose surface rasps the fruit surfaces causing some of the essential oil<\/a> cavities on the peel to
\nburst and release their oil-water emulsion. This screw further transports the fruit into a hopper in
\nwhich rollers covered with abrasive spikes burst the remaining oil cavities. The oil and water
\nemulsion is washed away from the fruit by a fine spray of water. The emulsion next passes
\nthrough a separator where any solids are removed, after which it passes through two centrifugal
\nseparators working in series to yield the pure oil. Most bergamot oil and some lemon oil are\u00a0produced this way in Italy.<\/p>\n

Sfumatrice Process<\/strong>
\nThe sfumatrice equipment consists of a metallic chain that is drawn by two horizontal
\nribbed rollers. The peels are conveyed through these rollers during which time they are pressed
\nand bent to release their oil. As in pelatrice, the oil is washed away from the sfumatrice rollers
\nby fi ne sprays of water. Again, the oil is initially passed through a separator prior to being sent
\nto two centrifuges in series, so that purified oil can be produced. At one time, sfumatrice was the
\nmost popular process for citrus oil isolation in Italy; however, today the pelatrice method
\nappears more popular.<\/p>\n

Essential Oil Extraction with Cold Fat (Enfleurage)<\/a><\/strong>
\nDespite the introduction of the modern process of extraction with volatile solvents, the
\nold fashioned method of enfleurage, as passed on from father to son and perfected in the course
\nof generations, still plays an important role. Enfleurage on a large scale is today carried out only
\nin the Grasse region of France, with the possible exception of isolated instances in India where
\nthe process has remained primitive.
\nThe principles of enfleurage are simple. Certain flowers (e.g. tuberose and jasmine)
\ncontinue the physiological activities of developing and giving off perfume even after picking.
\nEvery jasmine and tuberose flower resembles, so to speak, a tiny factory continually emitting
\nminute quantities of perfume. Fat possesses a high power of absorption and, when brought in
\ncontact with fragrant flowers, readily absorbs the perfume emitted. This principle, methodically
\napplied on a large scale, constitutes enfleurage. During the entire period of harvest, which lasts
\nfor eight to ten weeks, batches of freshly picked flowers are strewn over the surface of a
\nspecially prepared fat base (corps), let there (for 24 h in the case of jasmine and longer in the
\ncase of tuberose), and then replaced by fresh flowers. At the end of the harvest, the fat, which is
\nnot renewed during the process, is saturated with flower oil. Thereafter, the oil is extracted from
\nthe fat with alcohol and then isolated.
\nThe success of enfleurage depends to a great extent upon the quality of the fat base
\nemployed. Utmost care must be exercised when preparing the corps. It must be practically
\nodorless and of proper consistency. If the corps is too hard, the blossoms will not have sufficient
\ncontact with the fat, curtailing its power of absorption and resulting in a subnormal yield of
\nflower oil. On the other, if it is too soft, it will tend to engulf the flowers and the exhausted ones
\nwill adhere; when removed, the flowers will retain adhering fat, resulting in considerable
\nshrinkage and loss of corps. The consistency of the corps must, therefore, be such that it offers a
\nsemihard surface from which the exhausted flowers can easily be removed. The process of
\nenfleurage is carried out in cool cellars, and every manufacturer must prepare the corps
\naccording to the prevailing temperature in the cellars during the months of the flower harvest.<\/p>\n

Many years of experience have proved that a mixture of one part of highly purified tallow
\nand two parts of lard is eminently suitable for enfleurage. This mixture assures a suitable
\nconsistency of the corps in conjunction with high power of absorption. The fat corps thus
\nprepared is white, smooth, absolutely of uniform consistency, free of water and practically
\nodorless. Some manufacturers also add small quantities of orange flower or rose water when
\npreparing the corps. This seems to be done for the sake of convention. Such additions somewhat
\nshade the odor of the finished product by imparting a slight orange blossom or rose note.<\/p>\n

Enfleurage and Defleurage<\/strong>
\nEvery enfleurage building is equipped with thousands of socalled chassis, which serve as
\nvehicles for holding the fat corps during the process. A chassis consists of a rectangular wooden
\nframe. The frame holds a glass plate upon both sides of which the fat corps is applied with a
\nspatula at the beginning of the enfleurage process. When piled one above the other, the chassis
\nform airtight compartments, with a layer of fat on the upper and lower side of each glass plate.
\nEvery morning during the harvest the freshly picked flowers arrive, and after being cleaned of
\nimpurities, such as leaves and stalks, are strewn by hand on top of the fat layer of each glass
\nplate. Blossoms wet from dew or rain must never be employed, as any trace of moisture will turn
\nthe corps rancid. The chassis are then piled up and left in the cellars for 24 h or longer,
\ndepending upon the type of flowers. The latter rest in direct contact with one fat layer (the lower
\none), which acts as a direct solvent whereas the other fat layer (beneath the glass plate of the
\nchassis above) absorbs only the volatile perfume given off by the flowers.<\/p>\n

After 24 h, the flowers have emitted most of their oil and start to wither, developing an
\nobjectionable odor. They must then be removed from the corps, which process, despite all efforts
\nto introduce labor-saving devices, is still done by hand. Careful removal of the flower
\n(defleurage) is almost more important than charging the corps on the chassis with fresh flowers
\n(enfleurage) and, therefore, the persons doing this work must be experienced and skilled. Most of
\nthe exhausted flowers will fall from the fat layer on the chassis glass plate when the chassis is
\nstruck lightly against the working table, but since it is necessary to remove every single flower
\nand every particle of the flower, tweezers are used for this delicate operation.
\nImmediately following defleurage, that is, every 24 h, the chassis are recharged with
\nfresh flowers. For this purpose the chassis are turned over and the fat layer, which in the previous
\noperation formed the top (ceiling) of the small chamber, is now directly charged with flowers. In
\nthe case of jasmine, the entire enfleurage process lasts about 70 days: daily the exhausted flowers
\nare removed and the chassis are recharged with fresh ones. At the beginning of, and several times
\nduring, the harvest, the fat on the chassis is scratched over with metal combs and tiny furrows are
\ndrawn in order change and increase the surface of absorption.
\nAt the end of the harvest, the fat is relatively saturated with flower oil and possesses the
\ntypical fragrance. The perfumed fat must then be removed from the glass plates between the
\nchassis. For this purpose, it is scraped off with a spatula and then carefully melted and bulked in
\nclosed containers. The final product is called pomade (pomade de jasmine, pomade de tuberous,
\npomade de violet, etc.). The most highly saturated pomade is pomade no. 36, because the corps
\non the chassis have been treated with fresh flowers 36 times during the whole process of
\nenfleurage.
\nAt the beginning of the harvest, every chassis is charged with about 360 g fat corps on
\neach side of the glass plate, in other words, with 720 g per chassis. Every kilogram of fat corps
\nshould be in contact with about 2.5 kg (preferably with 3.0 kg) of jasmine flowers for the entire
\nperiod of enfleurage, which lasts from 8 to 10 weeks. The quantities differ somewhat for
\ndifferent flowers. At the end of enfleurage, the fat corps has lost about 10% of its weight because
\nof the various manipulations.
\nIn this process, the long enfleurage time is reduced by the immersion of petals in molten
\nfat heated at 45\u00b0-60\u00b0 C for 1 to 2 h, depending upon the plant species. After each immersion, the
\nfat is filtered and separated from the petals. After 10 to 20 immersions, the fat is separated from
\nwaste flowers and water. Absolute of maceration is then produced from fat containing oil
\nthrough the process of extraction and concentration under reduced pressure. It is mainly used for
\nhighly delicate flowers whose physiological activities are lost rapidly after their harvest, such as
\nlily of valley.
\nModern (Non-traditional) Methods of Extraction of Essential Oils<\/strong>
\nTraditional methods of extraction of essential oils have been discussed and these are the
\nmethods most widely used on commercial scale. However, with technological advancement, new
\ntechniques have been developed which may not necessarily be widely used for commercial
\nproduction of essential oils but are considered valuable in certain situations, such as the
\nproduction of costly essential oils in a natural state without any alteration of their
\nthermosensitive components or the extraction of essential oils for micro-analysis. These
\ntechniques are as follows:
\n\u2022 Headspace trapping techniques
\n– Static headspace technique
\n– Vacuum headspace technique
\n– Dynamic headspace technique
\n\u2022 Solid phase micro-extraction (SPME)
\n\u2022 Supercritical fluid extraction (SFE)
\n\u2022 Phytosol (phytol) extraction
\n\u2022 Protoplast technique
\n\u2022 Simultaneous distillation extraction (SDE)
\n\u2022 Microwave distillation
\n\u2022 Controlled instantaneous decomposition (CID)
\n\u2022 Thermomicrodistillation
\n\u2022 Microdistillation
\n\u2022 Molecular spinning band distillation
\n\u2022 Membrane extraction<\/p>\n

Some of these techniques are discussed in other chapters. Here, a few important, relevant
\nreferences are provided.
\nConclusions<\/strong>
\nSome of the major constraints in sustainable industrial exploitation of medicinal and
\naromatic plants (MAPs) are due to the fact that the countries of South East Asia have poor
\nagricultural practices for MAPs, unscientific and indiscriminate gathering practices from the
\nwild, poor postharvest and post-gathering practices leading to poor quality raw material, lack of
\nresearch for the development of high-yielding varieties of MAPs, poor propagation methods,
\ninefficient processing techniques, poor quality control procedures, lack of research on process
\nand product development, difficulty in marketing, non-availability of trained personnel, lack of
\nfacilities and tools to fabricate equipment locally, and finally lack of access to the latest
\ntechnologies and market information. This calls for co-operation and coordination among various
\ninstitutes and organizations of the region, in order to develop MAPs for sustainable commercial
\nexploitation.
\nThe process of extracting MAPs determines how efficiently we add value to MAP
\nbioresources. In the case of essential oils<\/a>, the extraction process affects the physical as well as
\ninternal composition. External appearance, at times, can result in rejection of the batch even if
\nthe analytical results are within acceptable limits. Furthermore, essential oils are evaluated
\ninternationally for their olfactory properties by experienced perfumers and these olfactory
\nqualities supersede analytical results. Variations in the chemical constituents of the extracts of
\nmedicinal plants may result by using non-standardized procedures of extraction. Efforts should
\nbe made to produce batches with quality as consistent as possible (within the narrowest possible
\nrange).<\/p>\n","protected":false},"excerpt":{"rendered":"

Expression or cold pressing, as it is also known, is only used in the production of citrus peel are crushed or broken to release the oil. One method that was practiced many years ago, particularly in Sicily (spugna method), commenced with halving…Read More »<\/a><\/span><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[4,40],"class_list":["post-98","post","type-post","status-publish","format-standard","hentry","category-essential-oil-distillation","tag-essential-oil","tag-essential-oil-extraction"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.essentialoilmach.com\/blog\/wp-json\/wp\/v2\/posts\/98","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.essentialoilmach.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.essentialoilmach.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.essentialoilmach.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.essentialoilmach.com\/blog\/wp-json\/wp\/v2\/comments?post=98"}],"version-history":[{"count":2,"href":"https:\/\/www.essentialoilmach.com\/blog\/wp-json\/wp\/v2\/posts\/98\/revisions"}],"predecessor-version":[{"id":107,"href":"https:\/\/www.essentialoilmach.com\/blog\/wp-json\/wp\/v2\/posts\/98\/revisions\/107"}],"wp:attachment":[{"href":"https:\/\/www.essentialoilmach.com\/blog\/wp-json\/wp\/v2\/media?parent=98"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.essentialoilmach.com\/blog\/wp-json\/wp\/v2\/categories?post=98"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.essentialoilmach.com\/blog\/wp-json\/wp\/v2\/tags?post=98"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}