herbal extracts


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Slide 1: 

Study of Herbal Extract Nilesh Gupta TIPER, Meerut

Topics To Be Covered Are As Follows: : 

Topics To Be Covered Are As Follows: Types of Herbal Extracts Extraction Processing Equipments

What are herbal extracts? : 

What are herbal extracts? Drug extracts are preparations obtained by extracting herbal drug of certain particle size with suitable extraction medium [Menstura]. The extraction can be accomplished by various methods. The extracts obtained after separation of liquid from the drug residue is called micelle and left over as ballast material. The micelle can be converted to ready to use medicinal preparation. Eg. Fluid extract and tinctures.

Terminology: : 

Terminology: Menstrum: Solvent or solvent mixture used for extraction. Micella: Solution containing extracted substances. Rinsing: Dissolution of extractive substances out of disintegrate cell. Lixiviation: Extraction with water as solvent or leaching


CLASSIFICATION OF EXTRACTS Aqueous Drug Extracts Decoction Infusion Maceration Tinctures Fluid extracts Thin extracts Thick extracts or viscous extracts Dry extracts Oily drug extracts or ole medicate Oleoresins

Aqueous Drug Extracts : 

Aqueous Drug Extracts These are described as medicinal preparation as dispensing medicines intended to be used immediately after preparation or to be preserved for use for specified period. There are three methods generally used for their preparation. Decoction : It is the process of extracting the hard and woody crude drugs wherein the water is used as Menstrum and crude drugs are boiled along with Menstrum decoction differs from the infusion in respect of that the crude drug in infusion are not boiled with the Menstrum but only boiling Menstrum is poured over the crude drugs.

Slide 7: 

Infusions: It is the process of extracting the vegetable drug, wherein boiling water is used as Menstrum. The process consists of treating vegetable crude drugs with boiling water but the drugs are not boiled with menstrum. The mixture is allowed to cool, filtered and dispensed. Maceration: maceration is “Place the solid materials with whole menstrum in closed vessels and allow to stand for several days shaking occasionally strain, press the marc and mix the liquid obtained clarify by subsidence or filtration.” Two types of maceration: Simple maceration Double or Triple maceration

Tincture: : 

Tincture: These are alcoholic preparations containing the active principles of vegetable drugs. These are the extracts prepared from drug plants by using varying concentration of ethanol with certain additives in such a way that one part of drug is extracted with 2-10 parts of menstrum. Drug and whole of the menstrum shaken occasionally for seven days in closed containers. Strain, press the marc, and clarify by subsidence or filtration. Filtrate is not adjusted to volume (organized drug).

Fluid Extracts : 

Fluid Extracts These are similar to the tincture and are liquid preparations. These are more concentrated and as per recommended of standard texts, 2 parts of fluid extract is made from one part of drug. Some pharmacopoeia give rigid limits for the ratio of drug to total extract but permits the micelle obtained to be adjusted to certain active compounds.

Thin Extracts : 

Thin Extracts These are also known as extract tennua. These prepared as liquid extracts but concentrated to a honey like consistency

Thick Extracts : 

Thick Extracts These extract are thickly liquid or viscous when warm but are not fluid at room temperature and are not obtained from micelle by extensive but fairly careful concentration. They are plastic masses containing varying quantities of residual moisture and can be adjusted to a defined strength of active substance by addition of calculated quantities of inert substances like Dextrin, Lactose etc. They have been completely replaced by dried extracts because of their low stability and their low stability and their susceptibility to microbial growth.

Dry Extracts : 

Dry Extracts These extract are the plant preparations obtained by the concentration and drying of liquid extracts under mild conditions.

Oily Drug Extracts : 

Oily Drug Extracts These preparations are made by suspending ground drug material into non-drying oil adopting maceration process. Mild heat can also be used for enhancing the extraction in short duration. Examples: Aconite, Arnica blossom, Marigold, Rose flower etc.

Oleoresins: : 

Oleoresins: These are the preparation made by extracting oleoresinous material like plant gum and resins from spices with suitable solvents like ethanol/ ethyl acetate.


PROCESSING THE FOLLOWING STEPS ARE INVOLVED IN PROCESSING. Communition / Pulverization Extraction Purification of Miscellae Concentration of miscellae Drying of extracts Pulverization of dry extracts.

Communition: : 

Communition: It is a process of fragmenting a substance into small particles by mechanical forces. The basic object of communition of herbal drugs is to obtain fractions in high field and as free of dust as possible.

Extraction : 

Extraction The extraction of drugs represents a solid from solid preparation, as solid components must be extracted from a solid substance. This type of extraction is generally known as solid- liquid extraction as the solid drug is extracted with a liquid medium. In the extraction of plant material two processes run parallel with each other. That is as rinsing of extractive substances of disintegrated plant cell and dissolution of extractive substances out of the intact plant cells by diffusion.

Slide 18: 

The processes commonly used by different manufactures are as follows:- Maceration; kinetic maceration, remaceration and digestion. Percolation and repercolation Turbo extraction Counter- current extraction Ultra sound extraction Extraction by electrical energy Extraction with gases.


INSTRUCTION PRIOR TO EXTRACTION Before the herb is taken for processing, be sure that it is the correct herb. This should be done with the authentic research centre. Reducing the herb to a proper size fit for extraction. If the size is more than optimum required in extraction, the extraction will be incomplete. If the size is less than optimum size, there will be canalizations of solvent so extraction again will not be complete. The herb should be soaked with the solvent to be used, prior to extraction for a period of 8-48 hours as may differ from herb to herb. The harder the fiber of herb, the more time should be taken for soaking.


CHOICE OF SOLVENTS:- As per the Pharmacopoeial guidance, if the herb extraction is given in prescribed pharmacopoeias, then we can straight way use the same solvent in our work. If it is not available, then we have to go by the active principles of the plant as gleaned from literature. In some cases a particular solvent may be used with a view to isolate any active ingredient from a herb as compared to all active ingredients in the total extract.


TEMPERATURE It should not exceed 80º C in any case but it should be preferably be between 60-70º C occasionally, lower temperature upto 50º C may also be required depending upon the herb and the purpose of extraction


TYPES OF EXTRACTION:- Solid liquid extraction :- This may be done by maceration, percolation or automatic solvent extraction plant. Liquid liquid extraction :- This is isolation of fine active particles from the extract, which may be of two types: A) Extraction with solvent heavier than H2O. B) Extraction with solvent lighter than H2O. 3. After liquid extraction, we may have to crystallize the active ingredients in a crystallizer drying is generally done in F.B.D., at a temperature not exceeding 60º C.


DRYING OF EXTRACTS:- Spray drying is the best to be used at a temperature of 150º C. The spray drying is quick system of drying and preferred over other systems of drying, particularly in case of heat sensitive products. Spray dryer is vastly used for entrapping volatile constituents of extract within the particle and this process is called micro encapsulation. FBD is generally preferred for drying however vacuum tray dryer is also used at a temperature not exceeding 60º C in cases where products are prone to oxidation. Vacuum rotary-drying system is also used for drying of herbal concentrates. The ideal condition for spray during extracts is: Solid in feed : 25-35% Inlet temperature : 150-170º C Out let : 80-85º C


PLANT AND EQUIPMENT FOR PROCESSING HERBAL EXTRACTS Introduction: There are thousands of herbs which can be processed to prepare their extracts in the form of liquid, paste and powders. By its nature the processing of herbs impose the following constraints on the manufacturing equipments:

Slide 25: 

Clean, uncontaminating environment:- All the equipment should be in stainless steel of required quality to with stand temperature, pH conditions. Also, the internal surface should be smooth and polished so that sticking and subsequent contamination for next batches will be minimum. Processing of Heat sensitive Material: Normally, all herbal extracts are heat sensitive more so, when they are in concentrated from the subject for heating / boiling / drying at low temperature. The exact temperature of each operation can be decided only by prior experience or by trial or error.

Slide 26: 

Processing of sticky/ hygroscopic material: A large number of extracts, liquid and powders are sticky and provide problems in processing and handling. Under such circumstances, the selection of equipments to be done on the criterion of ease of cleaning & ultimate product recovery rather than ease of operation and other fringe benefits like heat recovery etc. Processing with volatile solvents: Some of the extracts can only be obtained with the use of volatile solvents, which are subsequently distilled off & recycled back. A good system under gadgets for producing vacuum and condensing the solvent vapors. A refrigerated vent condenser is recommended for recovering solvent from the out going air of vacuum system.


PROCESS AND EQUIPMENT: SIZE REDUCTION: The size reduction is the process of reducing the particle size of a substance to a finer state of subdivision to smaller pieces, to coarse particles or to powder. Communition and grinding are the synonym terms used for the process of size reduction when the particle size of solids is reduced by mechanical means it is known as milling. Pharmaceutical application of size reduction: Size reduction which increases the surface area of drugs which enhances the extraction. The mixing of several solid ingredients is easier and more uniform if ingredients are reduced to same particle size. On reducing the particle size the bulkiness of the certain drugs can be increased


JAW CRUSHER Used for primary size reduction up to sizes of 5-10mm. there are two distinct types of jaw crushers, the blake and the dodge. The blake is commonly used one. This crusher is made by many concerns, and each maker has own design.


HAMMER MILL:- The hammer mill operates on the principle of impact between rapidly moving hammers mounted on a rotor and the powder material. The final size reduction (upto the size of 100-200 mesh).


MAGNETIC SEPAREATOR:- It is mainly used to remove iron trash from the feed to size reduction equipment.


BELT CONVEYOR Principle:-Horizontally or inclined placed motor driven rotating belt on pulleys convey the material from feeding point to the discharge point.


DUST COLLECTING EQUIPMENT To maintain the dust-free atmosphere in the manufacturing area and to attain better yields by minimizing the raw material losses. E.g.:- Trolleys / Handcrats / Fork lift trucks. These are used for material handling of raw material before and after size reduction.


EXTRACTION:- Extraction equipments provide the efficient contact of herbs & solvents. In the most primitive stage, the equipment would involve boiling solvent with herbs in a kettle for sufficient time & removing extracts from bottom. The exhausted mass of herb is subjected to repeat extraction process or is allowed to stand till sufficient extract is drained off it. A further refinement is the design which provides a false bottom above which herbs are charged and the solvent is circulated through it by an external circulation pump. The solvent is heated to requisite temp to effect optimum extraction keeping in view the temp sensitivity of the product. The extractor can be used of various types:- Batch or continuous extractor open or closed extractor with or without facility for handling the solvents


FILTERATION:- It may be defined as the process in which solids are separated from liquids by means of a porous medium which retains the solids but allows the liquid to pass through it. The exhausted mass is a liquid of about 2-5% dissolved solids. However it also contains considerable quantity of insoluble which are considered as impurities and will add to the ash content of the final product. The filtration equipment can be selected from the following options.


PLATE AND FRAME FILTER PRESS Principle:-The mechanism is surface filtration. The slurry enters the frame by pressure and flows through the filter medium. The filtrate is collected on the plates and sent to the outlet. A number of frames and plates are used so that surface area increases and consequently large volumes of slurry can be processed simultaneously with or without washing.


FILTER LEAF Principle:- :- Filter leaf is an apparatus consisting of a longitudinal drainage screen covered with a filter cloth. The mechanism is surface filtration and acts as sieve or strainer. Vacuum or pressure can be applied to increase the rate of filtration.


DRUM FILTER Principle:- Rotary drum filter functions on the principle of filtering the slurry through sieve-like mechanism on a rotating drum surface, under the conditions of vacuum. In addition, compression, drying and removing the filter cake (using a knife) are possible.

Nutch filter : 

Nutch filter


EVAPORATION / DISTILLATION Evaporation may be defined, as the removal of liquid from the solution by boiling in a suitable vessel from where the vapors are withdrawn and a concentrated liquid is left behind evaporation is maximum at boiling point of the substances. Distillation is the process of separating the constituents of a liquid by vaporizing the liquid and passing the vapors through a cold surface there by converting the vapors again to a liquid. Hence it involves a change of state from liquid to vapor again to liquid. Example:- climbing film evaporator, falling film evaporator, short tube evaporator etc.

Tray dryer : 

Tray dryer Principle: In tray dryer, hot air is continuously circulated. Forced convection heating takes place to remove moisture from the solids placed in trays. Simultaneously moist air is removed partially. Note: Turbulent flow lowers the partial vapors pressure in the atmosphere and also reduces the thickness of the air boundary layer.

Drum dryer : 

Drum dryer Principle:- In this , a heated metal drum rotates on its longitudinal axis, which is partially dipped in the solution to be dried. The solution is carried by the surface of the dryer and dried to form a layer. A suitavle knife scraps the dried material, while the drum is rotating.

Spray dryer:- : 

Spray dryer:- Principle:- The fluid to be dried is automized into fine droplets, which are thrown radially into a moving stream of hot gas. The temperature of the droplets is immediately increases and fine droplets get dried instantaneously in the spherical particles. This process completes in a few seconds before droplets reaching the wall of the dryer. Working steps: Atomization of the liquid. Drying of the liquid droplets Recovery of the dried products.

Fluidised bed dryer: : 

Fluidised bed dryer: Principle: hot air is passed through a perforated bottom of the container containing granules to be dried. The granules are lifted from the bottom and suspended by the stream of air. This condition is called Fluidized state. The hot gas is surrounded every granule to completely dry them. Thus, material or granules are uniformly dried.

Slide 46: 

Tunnel dryer


UTILITIES EQUIPMENT Demineralised Water plant :- In case of water contains hardness by way of carbonates and sulfates, it will contribute towards the impurities by way of ash content. Hence the need of providing a dematerialized plant which will keep the impurities in control. Ion exchange resins provided in the dematerialized plant will remove the impurities in the water. The resins need a periodical re-generation to maintain efficiency of demineralization. A properly sized dematerialized plant can have a comfortable regeneration cycle.

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Boiler:- Selection of steam boiler depends on the size of herbal processing unit from the following alternatives. Coal Fired Boiler:- Through this boiler is not quite fuel efficient and is one which creates considerable air pollution, it is the most inexpensive version available. It also facilitates use of exhausted dried herbs a supplementary fuel in the boiler. Steam pressure required by the system is to order of 3kg / cm2 Light Diesel/ Furnace Oil fired baby boiler:- These boilers are out of IBR range and are normally of capacity in the range of 500kg/hr, the steam goes through a coil providing less volume for the steam side. These boilers are available in automatic version and need very less of supervision. The thermal efficiency of the boiler is in the range of 80% and above. These boilers carry statutory incentives and hence could be the best selection.

Slide 49: 

Packaged Boiler:- These boilers are LOD / Furnace oil fired and have good efficiency. However, they are meant for large capacities and generally fall under IBR Act. Cooling Tower:- Normally cooling water supply temperature is selected at about 30° C. the cooling water flow rate can be calculated from thermal boiler and the thermal temperature of cooling water. Cooling water is required for: Spray Ponds:- This is the simplest way of getting cold water. A big underground water reservoir is provided. The water from the reservoir is pumped to the process and returned water is allowed to spray in the reservoir thereby creating cooling effect.

Slide 50: 

Natural Draft Cooling Tower:- Here the return water is sprayed from a height of about 2500mm or above. The droplets of water are falling on AC sheet around the reservoir. Forced / Induced Draft Cooling Tower:- In this type of cooling tower rather then depending on the drop of natural air, a forced or induced draft of air is provided by centrifugal / suction fan provided in the cooling tower. These cooling towers are available in wooden / FRP. The advantage of these cooling towers is reduced floor space and fall proof performance. Refrigeration Plant:- Normally a packaged water chilling plant should solve the purpose for common requirements. The chilled water produced by such units is circulated through vent condenser or such other equipment as may be required. Air Compressor:- Normally air compressor would be required for blowing off filtrate from the filter press(this small precaution improve the product yield) or for any instrumentation provided.

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