FAIR-CT96-2003 EXTEN: Volume extraction and encapsulation of substances used as flavour chemicals, pharmaceutical raw substances, biochemicals and enzymatic systems

Contacts
Summary Information



To find similar Items, click on a keyword below:
Biological Conversion : Biotechnology : Enviromental Aspects : FAIR Area 1.2 - Green Chemicals and Polymers Chain : Fine Chemicals : Flavours/Fragrances : Pharmaceuticals/Cosmetics : Process Engineering : Separation/Fractionation

	Proposal No:	FAIR-CT96-2003
	Date Prepared:	January 2000, May 1998
	Source:	Final Report Executive Summary Progress Report May 1998

---

Final Report Executive Summary

---

Progress Report May 1998

Introduction

The overall aim of this project is the development and realisation of a continuous, in-line process for the extraction and encapsulation of botanical substances. Conventional methods of solvent extraction, particularly within the pharmaceutical industries, involve leaching or percolation with an organic solvent such as dichloromethane or hexane. The need to select for a particular molecule leads to the use of these environmentally undesirable solvents, and residues in the extract can often cause problems for downstream processing. This project is developing a two-stage continuous extraction process based on the supercritical fluid extraction of an initial hydroalcoholic extract of the raw botanical material. Microencapsulation is often necessary for product preservation and functionality. For product preservation, particularly against atmospheric oxidation, it is desirable that encapsulation of the product should occur as an in- line process. Supercritical fluid techniques provide a solution here and the project is seeking to develop in-line encapsulation after the extraction process through the rapid expansion of the supercritical solution.

Objectives The specific objectives are:

• optimised, continuous hydroalcoholic extraction, reducing processing time by up to 20%
• selective processing of hydroalcoholic botanical extracts through supercritical fluid extraction, to obtain active molecules to high purity
• in-line encapsulation process to allow immediate encapsulation of extract for preservation and/or slow release

The work includes the following indirect objectives:

• model for mass transfer of active substances from botanical matrix into hydroalcoholic solution
• determination of phase equilibrium diagram for ternary system ethanol-water-carbon dioxide
• models of phase equilibrium of the active substances between hydroalcoholic liquid phase and supercritical phase
• the application of novel supercritical fluid chromatography and spectroscopic analysis techniques for the analysis of samples

Activities A list of test substances has been reviewed with unsuitable candidates rejected and alternatives suggested and the following activities carried out or planned:

• initial hydroalcoholic extraction experiments
• C0₂ solubility testing of pure samples of the test substances
• vapour-liquid equilibrium (VLE) experiments with hydroalcoholic extracts
• analysis of samples from hydroalcoholic extractions and VLE experiments
• correlation of thermodynamic data on ternary water-ethanol-CO₂ solvent system
• modelling of flow between first and second stage extractors
• modelling of mass transfer from botanical matrix to hydroalcoholic solvent
• design and construction of laboratory hydroalcoholic extractor
• assessment of particle size for optimum hydroalcoholic extraction
• evaluation of techniques and equipment for milling, cuffing and grinding of plant material
• specification and design of demonstration scale hydroalcoholic extractor
• two stage extraction experiments with laboratory column
• specification and design of second stage extraction column
• selection of techniques for separation of extract from column
• feasibility experiments with RESS and evaluation of results
• development of spray cooling technique and production of reference microspheres
• design and construction of pilot scale spray cooling plant
• initial design for an in-line encapsulation process
• preparation for a patent application

Progress

The project has made some good progress in this reporting period. However, this has followed a period of setbacks, including difficulties with modelling, delays in equipment procurement, and the rejection of test extract atropine on safety grounds, after considerable time had been spent studying it. Interesting results have been obtained concerning the hydroalcoholic extraction process and work in this area has been given greater emphasis than planned. With laboratory extraction experiments, it has been concluded that a continuous flow, dynamic extractor is not an option as it generates a particularly large amount of plant material fines. This creates problems for downstream processing. A static extraction approach will be used for scaled up plants.

Capsaicin and artemisinin have been chosen as the test extracts for development of the two stage extraction plant and laboratory two stage extractions have been carried out in order to prepare for specification and design of the two stage extraction plant. This has been done on a provisional basis pending further experimental results. A spray cooling technique has been developed to pilot scale. Further trials have shown that the initial concept is not feasible for in-line encapsulation. However, new concepts have been generated combining various processes and spray cooling.

Results The following have been achieved:

• measurement of C0₂ solubility for all test extracts
• optimisation of solvent composition and other parameters for hydroalcoholic extraction of camomile (apigenin), artemsia (artemisinin), and capsicums (capsaicin)
• correlation of thermodynamic data for spreadsheet to calculate phase composition for H₂0-EtOH-CO₂
• evaluation of pre-extraction treatments, including grinding, mixing, centrifugation and vacuum filtration
• specification and design of demonstration scale hydroalcoholic extractor
• laboratory two stage extraction experiments
• provisional specification and design of two stage extraction plant
• evaluation of RESS concept for in-line encapsulation
• development of pilot scale spray cooling microencapsulation plant
• creation of new in-line encapsulation concepts for investigation throughout the remainder of the project

Discussion At the beginning of this period, efforts to develop a thermodynamic computer model of the ternary water-ethanol-C0₂ solvent system had proved futile. The state of the art was simply not sufficiently advanced to be able to accurately predict solvent composition of this particular system. As an alternative, the fitting of polynomial expressions to the available experimental data to produce a workable correlation was found sufficient. Development of the hydroalcoholic extraction process continued with further work on capsicum extraction, confirming earlier results regarding optimum extraction times. The dynamic extraction process was rejected in favour of a static "coffee-pot" type extractor, owing to problems with sub-micron particles of plant material that are difficult to separate from the extract. A 500 1 demonstration plant has been specified and designed.

The test extracts were reviewed: atropine, artemisinin, capsaicin and coenzyme Q₁₀ were found to be sufficiently soluble in super critical CO₂ (SCCO)for industrial scale extraction. However, hypericin, parthenolide and apigenin were found insoluble, hence for these solvent extraction optimisation studies were performed. It was decided to broaden the scope of the two stage extraction work to include reverse extraction, using those extracts insoluble in SCCO as test extracts. Atropine was ruled out of the project at this point because of safety concerns, and so further development of the extraction process was carried out using capsaicin and artemisinin as primary test extracts to develop the plant itself.

Samples produced were analysed using SFC-MS. Work on hypericin and apigenin has been delayed because they required the negative ion mode of the mass spectrometer.

The optimum particle size for virtually all hydroalcoholic extractions has been determined, with investigations of various means of cutting, milling and grinding plant material to the required size specification.

The specification and design of the two stage extraction plant has been drawn up. Results from column experiments led to a provisional design, but further experiments are required. Provisional specifications for pumps and heat exchangers have been prepared on the strength of the work to date. A two stage process of cyclone and column has been selected for the extract separation stage, and various schemes for extract separation and solvent recycling are currently being evaluated.

An additional consideration is the requirement to integrate the in-line encapsulation stage. A spray cooling technique is being developed up to a pilot scale plant. A large number of encapsulate materials and actives have been tested, and various nozzle configurations used. The RESS experiment has been completed with the conclusion that this is not an option for an industrial in-line encapsulation process. New concepts for in-line encapsulation combine ideas from RESS, SASS and spray cooling processes. These will be evaluated with small alterations to existing laboratory equipment in the next reporting period.

Future activities Capsaicin and artemisinin will be used in further laboratory two stage extraction experiments, so that the design of the extraction plant can be finalised. Plant components will then be ordered, and it is anticipated that the plant will be commissioned by month 27. Activities will continue to focus on the hydroalcoholic extraction process with a demonstration plant commissioned by the end of 1998. Further experiments investigating the new concepts of in-line encapsulation will be carried out. If a concept is developed, then a pilot plant should be ready in months 27-30. Work will continue to develop the spray cooling process in its own right.