Medicated oils prepared using process as mentioned in Ayurveda are used for external and internal administrations to treat various disorders. Taila pak vidhi provides detailed description of such processes. Medicated oils are prepared by prolonged cooking of sesame oil with pasty mass of herbs and decoction of herbs in presence of large quantity of water. We report preliminary findings of physicochemical and chromatographic profiles of changes brought out by such processes and the role of each component. Changes observed when the processes were altered to deviate from those prescribed in Ayurveda are also reported.
Keywords: Ayurveda, herbalised oil process changes, medicated oils, oil soluble extractives
Ayurveda, a holistic health care system prescribes usage of different medicated oils for application on the body, with or with out massage for providing health benefits and to treat specific indications. While most of medicated oils are for external usage, certain types of medicated oils that are processed with milk are administered orally also. Detailed medicated oil processing is described in Ayurvedic textbooks recognized by Drugs and Cosmetic Act and in the Ayurvedic Formulary of India (AFI). Medicated oils have principally three components namely, drava or qwatha (a liquid which may be aqueous decoction of one or more herbs, or juice of herbs or milk), kalka (a fine paste of the herbs) and sneha dravya (a vegetable oil). Normally crude sesame oil (SO) is used as sneha dravya, though occasionally castor oil and coconut oil is also used either in parts or in full. As per AFI, unless otherwise given for any specific Ayurvedic oil recipe, the ratio of the three components are, kalka one part, sneha dravya four parts and drava should be 16 parts. The general process is that herbs are ground to get coarse powder (# 40) and mixed with just sufficient quantity of water to get a pasty mass to obtain the kalka. The raw or powdered herbs (# 10-30) is moistened with water and boiled with 16 times by volume of water to that of herb quantity and continued boiling to reduce the volume to one forth. The decoction is strained using a muslin cloth to obtain the qwatha (also written as kwatha some times). SO is taken in a vessel and heated for some time; mixed the pasty mass and the aqueous decoction together. This mixture is boiled on mild fire with stirring to avoid kalka to adhere to the vessel and boiling continued till all the water evaporates. Ayurvedic process prescribes to boil either till all the water from the decoction evaporates or the moisture in the pasty mass also evaporates. Well-cooked oil should not have any residual moisture (less than 0.1%). The oil is strained while warm through muslin cloth and allowed to cool. As per AFI, when processing is to be done where aqueous decoction is used as one component, the cooking processes need to be done for many days and up to 5 d in some cases.
Preparation of oils:
All the herbs were procured from local traders and authenticated by a qualified botanist in our research center. The oils were prepared at a small Ayurvedic pharmacy in a batch size of 1.5 liter each using stainless steel vessels and cooked on gas heaters under supervision of an ayurvedic physician (Vaidya). One batch of oil was also prepared by cooking SO using the volume of water same as that of decoction used in other batches, but with out any herb or pasty mass of herb referred as “aqua treated SO”. No antioxidants or stabilizers were added to any of the batches externally. One batch of oil was prepared in a pressure cooker to reduce the time of cooking and obtain removal of water at a faster rate, while all other cooking was done exactly as per AFI process in open vessels. The finished oils were transferred to clean and dry amber color stopperd bottles and stored at ambient temperature. Samples from these batches were used for all analysis. Crude SO from the same batch was used to prepare all the oils. It was observed that the temperature of the oil during the process of cooking was well below 100°, except in the last stage when most of the water has evaporated, it reaches 105-110° for a short while. In the batch where the cooking was done under pressure the temperature could have gone up to 125°.
All the oil samples were investigated visually for description, color, and were evaluated for odor and physicochemical properties like saponification and iodine values. In order to evaluate any degradation of the sesame oil these oil samples were evaluated for acid and peroxide values. Further they were analysed by gas chromatography standard techniques by using pure reference standards of fatty acids with a view to determine the fatty acid composition and to map any changes in the same. In order to find the percentage of herbal components that could have got extracted in to SO, a literature search was done to find out any published method for determination of extractive values. However no such method was found. The difficulty in finding the extractive values of herbal components dissolved in the oils is due to non-availability of a solvent, which would specifically and selectively extract out either the oil or the herbal components. Hence we developed a method where aqueous methanol was used to extract the herbal components from the cooked oils processed as above.