Importance of fermentations in Ayurvedic medicines

Ayurveda is considered by many scientists to be the oldest healing science. In Sanskrit, Ayurveda means “The Science of Life.” Ayurvedic knowledge originated in India more than 5,000 years ago and is often called the “Mother of All Healing”. Ayurveda translates into knowledge (Veda) of life (Ayur) and is one of the oldest and still widely practiced medical systems in the Indian subcontinent. 

The concept of Ayurvedic medicine is to promote health, rather than to fight disease, and Ayurveda in daily life aims at maintaining harmony between nature and the “individual” to ensure optimal health.

Ayurveda contains 8 branches of sciences and 10 different diagnostic tools based on tridosha theory (three humours of body). Ayurveda comprises of various types of medicines including the fermented forms namely arishtas (fermented decoctions) and asavas (fermented infusions). These are regarded as valuable therapeutics due to their efficacy and desirable features.

Arishtas and asavas are self-generated herbal fermentations of traditional Ayurvedic system. They are alcoholic medicaments prepared by allowing the herbal juices or their decoctions to undergo fermentation with the addition of sugars. Arishtas are made with decoctions of herbs in boiling water while asavas are prepared by directly using fresh herbal juices. Fermentation of both preparations is takes place by the addition of a source of sugar with dhataki (Woodfordia fruticose) flowers. Many preparations contain additional spices for improving their assimilation. They are moderately alcoholic (up to 12% by volume) and sweetish with slight acidity and agreeable aroma. Presence of alcohol in the preparation shows several advantages, like better keeping quality, enhanced therapeutic properties, improvement in the efficiency of extraction of drug molecules from the herbs and improvement in drug delivery into the human body sites.

 Indian Ayurvedic literature that included arishta and asava are Charaka Samhita, Sushruta Samhita, Astanga Hridaya etc.,

Asava-arishta is a novel yet least exploited continuous hydro alcoholic extraction method, being traditionally used in Ayurveda. This advanced dosage form results in the transformation of several phytochemical compounds present in the herbs, thereby either rendering them less toxic or more potent, besides helping in their faster absorption

Preparation of Arishta and Asava

The method of preparing asava arishtas is known as sandhana kalpana in Ayurveda. General methods used in the extraction of medicinal plants in asava and arishta are infusion and decoction.

Decoction: In this process, the crude drug is boiled in a specified volume of water for a defined time; it is then cooled and strained or filtered. This procedure is suitable for extracting water-soluble, heat-stable constituents. This process is typically used in preparation of Ayurvedic extracts called “quath” or “kawath”. The starting ratio of crude drug to water is 1:4 or 1:16. The volume is then brought down to one-fourth its original volume by boiling during the extraction procedure. Then, the concentrated extract is filtered and used as such or processed further.

Infusion: Fresh infusions are prepared by macerating the crude drug for a short period of time with cold or boiling water. These are dilute solutions of the readily soluble constituents of crude drugs.

The basic equipment required for preparation of arishta and asava is an earthen pot sufficiently large and glazed, porcelain jar of suitable size; a lid to close the vessel, a cloth ribbon to seal the vessel; a paddle like stirrer; a clean cloth of fine and strong texture for filtering, vessel to keep the juices or boil the drugs.

The major components are divided into 4 types according to their specific role in the process. These include: the main herbs from which the extract or decoction is taken out. They yield drugs, which are pharmacologically and therapeutically much important in the given medicine and the name of the medicine is derived from these herbs denoting their importance. The flavouring agents used in asava and arishta contribute to the flavour of the medicine and also have their own pharmacological action. The fermentation initiator provides inoculum for the fermentation to start. The medium of sugars is required for fermentation.

In Asokarishta, the main herb is Asoka. Other components which contribute for flavours are Cuminum cyminum L., Santalum album L. and Zingiber officinale Roscoe. Woodfordia fruticosa(L.) Kurz as fermentation initiator and jaggery as a source of sugar are also present. Similarly in Kanakasava, Kanaka  is the main herb while Piper longum L. and Zingiber officinale Roscoe contribute for flavor. Woodfordia fruticosa are mostly used in asava and aishta. All parts of this plant possess valuable medicinal properties and there is a heavy demand for the flowers, both in domestic and international markets specialized in the preparation of herbal medicines. This flower is pungent, acrid, cooling, toxic, alexiteric, anthelmintic, and is useful in thirst, dysentery, leprosy, blood diseases, toothache etc.,

Collection of plant material and preparation before fermentation

ü  Medicinal substances such as roots, leaves or barks, etc. are cut into pieces, and powdered or decoction. The basic drugs from which the extract is to be prepared are first cleaned and rinsed in water to get rid of dirt. In the case of fresh plants, they are cleaned, pulverized and pressed for collection of juice.

ü  If the drug is dry and to be used in the preparation of asava, it is coarsely crushed and added to water to which the prescribed quantities of honey, jaggery /or sugar are added.

ü  If it is an arishta, a decoction is obtained by boiling the drugs in the specified volume of water as given in the recipe. The water used should be clean, clear and potable. When the extracts are obtained, the sugar (cane sugar), jaggery/or honey are added and completely dissolved.

ü  The sugar, jaggery and honey should be pure. The jaggery to be added should be very old (prapurana) because fresh jiggery aggravates kapha and suppresses the power of digestion.

ü  The flavouring agents are coarsely powdered and added to the sweetened extract. Very fine powder of the flavouring agent is undesirable as it causes sedimentation in the prepared medicine and its filtration is difficult.

ü  In asavas, the avapa (drugs which are added in powder form at the end) should be one in tenth in quantity and honey should be three fourth in quantity of jaggery.

ü  The earthen pot or jar intended for fermenting the medicine is tested for weak spots and cracks and similarly a lid is also chosen. It should be prepared of the soft mud collected from the silt in the bank of river or lake. It should be greasy, thick, light and smooth. It should be free from holes or cracks and homogenous. The internal surfaces of the pot and the lid are wiped with a clean dry cloth and cow’s ghee is smeared on this surface to prevent oozing out of the contents. The pot should be perfectly dry before ghee is smeared and if it be moist, ghee will not stick, penetrate and block the pores. The infiltration of the pot prevents oozing and strengthens the pot. Glazed porcelain ware may also be used instead of earthen ware.

ü  In large scale, the fermentation is carried out in huge wooden vats with wooden covers. The vat is made air tight. The filtration is carried out by electric filter presses with filter sheets which efficiently separate the suspended particles and isolate clear medicine. The powdering, grinding and mixing are done by mills, pulverizers and mixing machines. The decoctions are prepared in large steam jacketed boilers, heated by superheated steam under pressure.

Inoculum

When the pot or the jar is ready, the sweetened and flavoured drug extract is poured into pot, up to three fourth of the capacity. The unfilled space provides room for the fermenting liquid when it rises up due to frothing and evolving of a large amount of gases. Otherwise, the medium may damage the container and flow out. Then, the inoculum has to be added to initiate fermentation. The process of fermentation necessitates the presence of fermenting microorganisms, yeasts.

In the preparation of alcoholic medicaments in the Ayurvedic Systems, the inoculum of yeasts comes from the dhataki flowers, which contain the wild species of yeast. These flowers are nectariferous and highly tanniferous. The flowers contain the yeast spores in the dry nectariferous region. The presence of tannin in flowers favours suitable environment for yeast growth. The flowers are added and the contents are stirred well to distribute the inoculum of yeast.

Apart from the fire flame flowers (dhataki), if other ingredients like honey and resins (gum) are added they also contain wild yeasts.

When fire flame flowers are not used in some preparations, the inoculum of yeasts is done either from the mahua flowers, honey or resins initiating the process of fermentation. The yeasts multiply rapidly by division in a short time.

Finally, the vessel should be closed and sealed. Sealing is done by winding around a long ribbon of cloth smeared with clay on one surface. While sealing, the blank surface of the ribbon should line the rim of the vessel and lid, the clay side should be external.

After sealing, the vessel is placed in a dark place without much circulation of air. It may be kept in a grain store buried in a heap of grain or into a pit in the soil. Soft packing of straw should be provided around the vessel to prevent breakage by any force

Fermentation Process

The fermentation vessel is left undisturbed for a month and then opened. The medicine is filtered and taken for use. If the filtered medicine shows further sedimentation, it is allowed to stand for few more days and again filtered to separate the sediment.

Fermentation processes help in rupturing of cells of the herbs and exposure of its contents to the bacteria and enzymes for transformation. Fermentation also creates active transport system with dissolved constituents from the herbal material. There are claims that yeast cell walls naturally bind heavy metals and pesticide residues and act as natural cleaning system, making self-fermentation of herbal products safer than powder decoctions

 Merits of the Fermentation Process

1.Fermentation removes most of the undesirable sugars from plant material, makes the product more bio-available and eliminates side effects such as gas and bloating.

2.Fermentation extracts a wider range of active ingredients from the herb than any extraction method since the broth undergoes a gradient of rising alcohol levels.

3.Yeast cell walls naturally bind heavy metals and pesticide residues and, therefore, act as a natural cleansing system.

4.Fermentation removes contaminants and can also lower the toxicity of some of the toxic components in plants.

5.Fermentation actively ruptures the cells of the herb, exposing it openly to the menstruum (solvents) and bacteria have enzymes that break down cell walls to further assist in the leaching process. Fermentation also creates an active transport system that moves the dissolved constituents from the herbal material to the menstruum (solvents).

The product of arishta and asava could end up with 79 products, of which 37 falls into the category of asava, 38 into arishta and the remaining 4 arishta are named as amirtha (Viswamritha, Balamritha and Swasamrutha, Vyoshamritha). These products have also been commercialized. Arishta and asava is used for the treatment of various problems in pediatrics, nervous system, blood and circulatory system, respiratory system, digestive and excretory system, urinary system, reproductive system, immune system, skin problems, worm infections, general illness and infectious diseases etc.

Thus, Arishta and asava are considered as best formulation in Ayurveda because they possess better keeping quality, which is likely due to the contribution of fermentation to preservation. The microbes involved in this process mediate this process; enhanced therapeutic properties, which may be due to the microbial biotransformation of the initial ingredients of arishta and asava into more effective therapeutics as end products, alcohol-aqueous milieu, which is also produced by microbes; improvement in drug delivery in the body is also increased due to alcohol-aqueous milieu. These products in general possess preservative properties, potentization of drug due to biotransformation mediated by native microbes