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  1. #1

    Default Manufacture of Concretes/Absolutes

    A manufacturer contacted me a while back for instructions on how to manufacture concretes/absolutes with hexane, etc. I didn't charge him for this, so I am happy to include some of the information below (minus his correspondence).

    Quote Originally Posted by Pears
    If you're open to using higher boiling solvents (hexane, etc.), then I'd suggest that you first read up on the methods historically used in France (see pages 81-103, below; for absolutes see also 122-126).

    https://archive.org/details/NavesMaz...s1947/page/n99


    If you look at figures 17 and 18 (pages 93 & 94), you will see a particular type of stationary extractor. Extractors of this general design are still used at the Sotraflor factory:

    https://ayalamoriel.com/blogs/smelly...elds-in-grasse

    http://www.lonny.com/Fall+Fashion+20...of+Chanel+No+5

    http://blog.unique-provence.com/2012...d-for-its.html
    Quote Originally Posted by Pears
    Extractors of the same general design are also used at the Robertet factory (see video):

    https://www.grasse-perfumery.com/pro...and-cosmetics/

    https://www.gettyimages.co.uk/detail...hoto/947574728


    And at a facility in India (1995):

    https://www.whitelotusaromatics.com/...ction_facility


    Tournaire market this type as their "Non-agitated Extractor":

    NON-AGITATED EXTRACTOR

    Designed for extraction and maceration of bulk large-particle-size
    products or sensitive materials like flowers.

    Loading and discharge using tiered grids.

    Residual solvent recovery from spent material using steam stripping.
    This is the equipment used for traditional maceration and extraction of
    a wide range of products for perfumes, flavourings and pharmaceuticals.
    http://tournairewpupload.s3.amazonaw...n-Fiche-UK.pdf


    It shouldn't be too difficult to convert a regular still into something similar. A pressure cooker or autoclave could be converted into a smaller version.

    Quote Originally Posted by Pears
    For further reading on the historical practices, see pages 200-213, below:

    https://archive.org/details/essentia...1mbp/page/n221


    For a more modern outline of the manufacturing process with a rotary extractor, see pages 10-13, below:

    http://krishna.nic.in/PDFfiles/MSME/...ine%20concrete[1].pdf

    [this link is now dead, see below for excerpt]


    See also section 7 (page 5), below:

    [https://www.researchgate.net/publica...stry_in_Turkey


    Modern rotary extractors are generally much larger than those of the early to mid 20th century. The manufacturer below offers something of a more moderate size (see image, "A Typical Rotary Extractor with Gear Box and Motor"):

    http://www.svengineers.co.in/#solvent-extraction


    With regard to the vacuum pump, ideally it should be the oil-free kind, as any solvent/water vapour that makes it's way past the condenser can contaminate the pump's oil. If yours isn't oil-free, then I'd strongly suggest that you add a cold trap. See below for more information:

    https://www.labconco.com/articles/ho...rect-cold-trap

    As mentioned above in parenthesis, one link is now dead. See below for an excerpt from the archived page (contains a few grammatical errors but the technical information is correct):

    BROAD OUTLINE OF MANUFACTURING PROCESS

    7.1. General details

    Step 1:
    Extraction of the freshly opened Jasmine flowers with a perfumery grade organic solvent

    Step 2:
    Removal of the solvent from the perfume material by evaporation

    Yield: 0.25 to 0.30%

    7.2. Description of the process

    Jasmine concrete extracted from Pitchi (Jasminum grandiflorum) is a wax like substance containing natural perfume with waxes and colouring material. It is being used in cosmetic industries and it fetches very high price in the international and domestic market.

    The jasmine flowers contain 0.25% of the perfume in the form of volatile oil and it can be extracted by means of solvent extraction method in which the principle is that the odoriferous substance of the flower is allowed to be absorbed by a highly volatile solvent and then the solvent is extracted.

    The fully opened flowers of jasmine should be picked in the early morning, which only contain high volatile content. Delay in picking beyond 9.30 A.M. leads to reduction in concrete yield due to increase in temperature and other climatic conditions.

    So it is essential to harvest the flowers in the early morning hours. While picking and transporting care should be taken not to damage the flowers. Since, the damaged flowers yield concrete with more percentage of unwanted wax and other plant materials.

    The harvested flowers are treated with the purified hexane at the rate of 1:2 ratio i.e for 1 kg of flowers require 2 kg of hexane. The purified hexane is a colourless solution with a boiling point ranging from 60 to 80 deg.C. The flowers are treated with hexane for about 30 minutes. To have the maximum content of concrete the treated flowers are rotated in a rotary type of extractor for about 20 minutes. The extractor contains four parts viz extractor, evaporator, condenser and vacuum distillation unit.

    After the complete extraction of perfume from flowers the solvent is filtered and concentrated by evaporation at a constant temperature at 75 deg.C. At this temperature, the solvent evaporate leaving the perfume and other plant waxes. The vapour of the solvent is condensed in to liquid for again for recycling. The concentrated liquid containing perfume wax pigments and solvent is distillation in a vacuum distillation unit. Where the complete removal of the solvent takes place, leaving the floral concrete in the form of molten wax.

    It involves two steps.

    * Dissolving the perfume material by treating the flowers with solvent.
    * Removal of the solvent from the perfume material by evaporation.

    Treating the flowers with solvent

    The fully opened flowers are treated with solvent by which the solvent penetrates into the flowers and dissolves the waxes, albumins and colouring materials.

    In solvent extraction process, the most important factor is the quality of the solvent used for this purpose, only the food grade hexane is used. Food grade hexane available in the market has to be purified before using it as a solvent by treating with liquid paraffin at 5% and distilled at 70 deg.C.

    The solvent would be slowly rotated for 25 minutes at the rate of 3 rotation per minute. After 5 minutes the flowers are allowed to stand in the solvent for another 20 minutes. During this process, the solvent absorbs the perfume of the flower.

    After mixing, solvent is drawn through the drain cock at the bottom of the extractor and filtered through a fine filter to remove the dust and unwanted materials. After that the solvent with perfume is removed and also the spent flowers are gently pressed to remove the remnant perfume with the flowers. However, it must be noted that the flowers should never be squeezed to remove the solvent completely.

    After that, the perfume laden solvent is lead into the evaporator. The evaporator is a wide mouthed circular bowel made in stainless steel with a capacity to hold 25 litres of solvent. It has an airtight lid with a hole at the centre for the outlet of the solvent vapour.

    The evaporator is heated over a water bath at a constant temperature of 75 deg.C. The water bath is heated electrically by two 2000 watt heating elements and the temperature is kept at 75 deg.C by thermostatic control. Temperature control is essential as high temperature and prolonged heat at atmospheric pressure will spoil the quality and appearance of the concrete. The evaporator should never be directly heated. It should be heated either over a water bath or by steam circulation. As the temperature rises in the evaporator, the hexane evaporates and the vapour escaped through the hole in the lid which is lead into the condenser through a stainless steel pipe.

    The condenser is also made of stainless steel and it contains several (12) small pipes fitted parallel through which solvent vapour is passed. By circulating cold water in the condenser continuously the solvent vapour is condensed and it is collected for recycling. The heating of the evaporator is continued till about 90% of the solvent is recovered by condensation which may take about 30 hours.

    The remaining 10% of the solvent containing all the aromatic oil and waxy material is transferred to vacuum distillation unit where the complete removal of the solvent is effected and the concrete is left in the still in the form of molten wax.

    Here also the still should not be heated directly. The heating should be done on a water bath. Since vacuum has been created into the still, the solvent evaporates quickly at lower temperature which is condensed in the condenser and collected for recycling. The heating should be continued till the last traces of hexane vapour in the condenser.

    After the complete removal of the solvent, a semi solid like brown substance is left in the still, which is the jasmine concrete of commerce.

    When the material is hot it has to be transferred to the container in which it is to be stored. When cooled, it solidifies and transfer to other containers may be difficult. The concrete can be stored in glass or aluminium containers.

    I hope that this proves helpful to you.

    Pears
    Last edited by Pears; 21st April 2019 at 07:48 PM.

  2. #2
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    Default Re: Manufacture of Concretes/Absolutes

    Paul Kiler
    PK Perfumes
    http://www.PKPERFUMES.com
    In addition to Our own PK line, we make Custom Bespoke Perfumes, perfumes for Entrepreneurs needing scents for perfumes or products, Custom Wedding Perfumes, and even Special Event Perfumes.

  3. #3

    Default Re: Manufacture of Concretes/Absolutes

    Thank you! I'm still a long way away from creating my own absolutes, but I do appreciate the sharing of information.

  4. #4

    Default Re: Manufacture of Concretes/Absolutes

    I'm glad that you found it of interest guys.

    It's worth mentioning that the vacuum pump should also be explosion-proof.

    The evaporator specified in the last excerpt is called a batch pan evaporator. These are less commonly used than they once were, at least for the primary evaporation stage. The advantages of batch evaporators in general are that they're easy to clean and maintain and are relatively inexpensive (although not in terms of their running cost). The disadvantages are that the heat transfer area (per unit volume) is quite small, the heat transfer coefficients tend to be low with natural convection and the residence time of the product is therefore long (i.e., not ideal for heat-sensitive materials). The use of vacuum and agitation can speed evaporation but process rates are generally still quite slow.

    For the primary evaporation stage, it is therefore now quite common to use film evaporators – particularly falling film evaporators. The main advantages are as follows:

    The falling-film evaporator has the advantage of gravity pulling the film downward. This results in a thinner, faster-moving film and gives high heat-transfer coefficients and short residence times in the heating zone. The falling-film evaporator is particularly useful in applications where the temperature driving force between the heating medium and the liquid is small (less than 15F). The combination of the ability to function at low temperature differences and short residence times makes the falling-film evaporator suitable for use with temperature-sensitive products.
    https://lcicorp.com/assets/documents..._Selection.pdf


    For small scale operations, you can of course use a rotary evaporator. Due to the centrifugal force and the friction between the wall and liquid, it is also able to exploit the effect of film evaporation.
    Last edited by Pears; 19th April 2019 at 03:47 PM.

  5. #5

    Default Re: Manufacture of Concretes/Absolutes

    Hi I see you started out your email with suggesting Hexane - does that mean you do find it superior to other solvents? Just wondering if it is about initial cost, ability to recycle, yield of material, or other.
    Thank you for this article. I think the most interesting is the evaporation and how much is recovered. Also the temperature, I think we assume heat will burn off aroma in the type of flowers that need solvent extraction. I saw an article that said when houses mature perfumes they go through a heat process before storage.

  6. #6

    Default Re: Manufacture of Concretes/Absolutes

    Hi Thea,

    I originally discussed both refrigerant gases and hexane with him.

    Historically, benzene and petroleum ether were mostly used. The former is carcinogenic and was therefore banned for such use. The latter is a mixture of hydrocarbons and typically contains some hexane. It is still used by some manufacturers, while others prefer to use hexane due to it's narrow boiling range and less variable characteristics. Which performs better in terms of yield and quality largely depends on the composition of the plant material.

    Heat is detrimental to some components, especially if the residence time is long. In the past few decades there has been a gradual move away from the use of higher temperatures. As an example, you may wish to read pages 13-31 from the following technical report:

    https://open.unido.org/api/documents...T%20(17515.en)
    Last edited by Pears; 13th April 2019 at 09:55 PM.

  7. #7

    Default Re: Manufacture of Concretes/Absolutes

    Thank Pears. I guess this P.E.O.R.C. is not something we can access, doesn't look like we have similar in states.

  8. #8

    Default Re: Manufacture of Concretes/Absolutes

    I wonder about benzyl benzoate. It's a relatively cheap solvent, and you wouldn't have to evaporate out much since quite a large amount can be left in there. It might work if you like balsamic smell in with the flowers.

  9. #9

    Default Re: Manufacture of Concretes/Absolutes

    Quote Originally Posted by Thea in Fl View Post
    I wonder about benzyl benzoate. It's a relatively cheap solvent, and you wouldn't have to evaporate out much since quite a large amount can be left in there. It might work if you like balsamic smell in with the flowers.
    But benzyl benzoate has a high boiling point. It wouldn't evaporate leaving the other fragrance molecules behind. The fragrance would evaporate first. (I imagine; I'm not a chemist.)

  10. #10
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    Default Re: Manufacture of Concretes/Absolutes

    Quote Originally Posted by Alysoun View Post
    But benzyl benzoate has a high boiling point. It wouldn't evaporate leaving the other fragrance molecules behind. The fragrance would evaporate first. (I imagine; I'm not a chemist.)
    Agreed, BB is going to last past the olfactory life of almost all other floral molecule types.
    Paul Kiler
    PK Perfumes
    http://www.PKPERFUMES.com
    In addition to Our own PK line, we make Custom Bespoke Perfumes, perfumes for Entrepreneurs needing scents for perfumes or products, Custom Wedding Perfumes, and even Special Event Perfumes.

  11. #11

    Default Re: Manufacture of Concretes/Absolutes

    Indeed, as Alysoun and Paul stated.

  12. #12

    Default Re: Manufacture of Concretes/Absolutes

    For further reading, see pp. 57-69, below. The information is taken from two of the books that I cited earlier, among others.

    https://www.unido.org/sites/default/...industry_0.pdf


    The primary evaporator depicted in 'Figure 1' (Meyer-Warnod, 1984) is a large batch evaporator. These are still used in some facilities (see here), while others employ the use of film evaporators. The primary evaporator depicted in 'Figure 2' (ibid.) is a rising film evaporator (falling film evaporators are now more commonly used for this purpose, but the basic principles are much the same).

    If you require equipment, technical support or training, then you can contact Tournaire's Equipment Division (see here).

    I hope that this proves helpful to you.

    Pears
    Last edited by Pears; 25th April 2019 at 02:30 PM.

  13. #13

    Default Re: Manufacture of Concretes/Absolutes

    Pears, this answered two nagging questions - are some materials chopped before extraction, and something about enfleurage I couldn't find anywhere else - thanks!

  14. #14

    Default Re: Manufacture of Concretes/Absolutes

    Great post Pears!

    I will set up a lab soon to experiment with the various flowers I see here in Thailand and this gathering of information is really helpful. There are a lot of wonderfully smelling stuff that don't even have English names here. It'll be fun.

    Cheers!

    Pelle




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