Evaluation of Physicochemical Properties and Chemical Constituents of Rasam , a Traditional South Indian Soup

Aims: To evaluate the physical and chemical properties of rasam , a traditional south Indian soup. Each ingredient present in rasam are known for their medicinal value individually. Moreover, rasam has being suggested as a general control measure in the treatment of SARS-CoV-2 by Ministry of AYUSH. For formulation designing the properties of material under study is generally determined. Hence, this study was carried out to evaluate the physiochemical properties of rasam so that it would be convenient to chose a suitable dosage form. Study Design: The physical and chemical studies was carried simultaneously in order to achieve the confirmatory results. Communication Place and Duration of Study: Study was performed at Parul Institute of Pharmacy & Research, Parul University, Vadodara, Gujarat, India. The study took about 45 days. Methodology: The physical parameters evaluated were pH, viscosity, density, boiling range, surface tension, miscibility, refractive index and loss on drying. The chemical evaluation included preliminary qualitative phytochemical screening. Results: The pH of rasam was 3.916 ±0.0133 , viscosity was 0.956 cp , d ensity was 0.993 g/mL, relative density was 0.995, boiling point was 110.3333 ± 0.333, surface tension was 107.093 N/m, refractive index was 1.37, and loss on drying was 80%. It contains several chemical constituents like alkaloids, glycosides, saponins, etc . Conclusion: The evaluated physical and chemical properties of rasam would provide a gateway for the formulation researchers to follow-up with various dosage forms designing.


INTRODUCTION
Food is consumed in various combinations, in comparatively bulk quantities which are not measured over vast socialized conditions. The outlook of considering food to have an expanded function which goes further than providing a source of nutrients truly applies to traditional functional foods. The organized method of consuming the traditional functional food provides a tremendous prophylactic to ward-off several diseases. Various literatures have recommended the consumption of foods rich in bio-active components, such as herbs and spices . for improved health [1]. The challenging reality of functional foods are not a mere nutritional and health provision rather the real challenge lies not in proving whether the functional foods have health benefits, but in defining their benefits and the development of methods to expose them by scientific means [2]. Rasam is a famous traditional soup of South India. It is consumed on a daily basis in every South Indian home. Rasam is traditionally prepared using tamarind juice as a base, with a variety of spices which are considered to be good for health and improving the digestion [3].
Rasam can be regarded as a classic example of an ideal recipe subscribing to the principles laid by Indian system of medicines such as Ayurveda and Siddha [4,5]. Rasam is recommended as one the general measures for the control of the fever and respiratory illness related to SARS-CoV-2 by the Ministry of AYUSH, Government of India [6].
Epidemiological randomized clinical trials carried out in different countries have demonstrated numerous health effects related to functional food consumption like reduction of cancer risk, improvement of heart health, stimulation of immune system, decrease of menopause symptoms, improvement of gastrointestinal health, maintenance of urinary tract health, antiinflammatory effects, reduction of blood pressure, maintenance of vision, antibacterial effect, anti-viral effect, reduction of osteoporosis and anti-obese effect [7]. The main spices used in the preparation of rasam are tamarind, turmeric, chili pepper, cumin, garlic, black pepper, black mustard, curry leaves, coriander and asafetida [8].
To explore the pharmaceutical potential of rasam beyond its culinary and nutritive effect, the ingredients used, their quantity, and process involved in the preparation of rasam has been standardized [9]. Other studies reported on rasam includes, marker based analytical studies [10], antimicrobial studies [11], cytotoxic, antimitotic, and antiproliferation studies [12], analytical studies by Gas Chromatography -Mass Spectrometry (GC-MS) [13] and breast cancer studies [14]. For formulation designing the properties of material under study is generally determined. Till now, the physical and chemical properties of rasam formulation have not been determined. Hence, there raised a need to evaluate the physical and chemical properties of rasam to open a gateway for the formulation researchers to follow-up with various dosage forms designs with rasam formulation.

Preparation of the Sample
Rasam was formulated as per Devarajan et al. 2017 [9]. The quantity of each ingredients, the number of hand crushing as in the case of tamarind in water, the number of poundings to ground pepper, cumin, chili pepper, garlic and the volume of rinsing water has been already standardized and reported [9]. The earlier study has also mentioned the sequence of adding different ingredients, utensils to be used and the temperature to be maintained during the preparation of rasam, same procedure was followed to prepare rasam for the current study. Dried tamarind fruit pulp (6.88 g) was soaked in 450 mL of water for 10 min. Then it was crushed in hand for 45 times and further strained and to which dried rhizome powder of turmeric (0.4 g) turmeric powder and sea salt (4 g) was added. In a separate container, fresh riped fruit of tomato (82.44 g) was crushed in hand 60 times. In a mortar and pestle, the dried long pepper chilli (1.33 g) was crushed 85 times, to which dried cumin fruits was added and crushed (2.67 g) for 100 times, then pepper (0.82 g) was added and crushed for 50 times, followed by cloves of garlic (9.63 g) and crushed for 90 times. The crushed tomato mixture and spice mixture tamarind was mixed together. The whole mixture was rinsed with 5mL water. In a stainless-steel bowl, Indian sesame oil (4 mL) was heated at 60°C for 2 min. After which, dried mustard seeds (0.82 g), whole chilli pepper (1.53 g) and fresh curry leaves (0.61 g) were added with an interval of 5s, 3s and 2s respectively. The whole mixture was added and rinsed with 20mL of water. The entire mixture was heated till frothing and fresh coriander leaves (1.50 g) and asafetida powder (0.05 g) was added and finally the heat source was terminated.

pH
The pH value of a solution was determined by means of a pH meter [15].

Viscosity
Viscosity was identified by using the Ostwald's viscometer as per the procedure mentioned in Indian Pharmacopoeia [16].

Density
Density was determined by the procedure from Indian Pharmacopoeia [17].

Relative density
Relative density was determined by the procedure mentioned in Indian Pharmacopoeia [17].

Boiling point
Boiling point was determined by the procedure mentioned in Indian Pharmacopoeia [18].

Surface tension
Surface tension was determined as per reported method [19].

Miscibility
The tests for the miscibility were determined by mixing rasam with equal volume of solvents and was allowed to stand for 5 minutes and the results were observed.

Refractive index
The refractive index of the rasam was observed by the Abbe's refractometer [20].

Loss on drying
Loss on drying was determined as per the method mentioned in Indian Pharmacopoeia [21].

Organoleptic properties
The organoleptic properties like color, odour and taste were determined.

Preliminary qualitative phytochemical screening
The phytochemical analysis were carried out as per reported methods [22,23].

Preparation of Rasam
Rasam, a traditional South Indian soup was prepared as per the method mentioned in Devarajan et al 2017 [9] (Fig. 1).

Physical Parameters
The parameters like pH, viscosity, density, relative density, boiling point, surface tension, refractive index, loss on drying, colour, taste and odour were determined (Table 1). All the parameters mentioned have determined for the first time. It is now known that rasam is acidic in nature. The viscosity and density are almost similar to water, but because of the dissolved solutes and solid residues the boiling point is higher as compared to water. The density and relative density do not show much variation. The miscibility data is as shown in Table 2. As water is the major component in rasam and also by its miscibility data it can be considered that rasam is moderately polar in nature like the alcohols.

Preliminary qualitative phytochemical screening
Some of the major chemical constituents present in the ingredients like tomato, turmeric, pepper, tamarind etc., used for the preparation of rasam are identified, but the chemical constituents present in the rasam are not yet identified. The results of various tests for the presence and absence of phytoconstituents are shown in Tables 3, 4, 5 and 6. The preparation of rasam involves heating the individual ingredients (numerous chemical constituents are present in each of the ingredients) in water and sesame oil. This processing provides tremendous opportunity for a completely altered/different chemical composition of the finally prepared rasam. Loss of active principles or synergetic effect or breakdown of inactive metabolite to an active one or formation of new chemical entities (NCEs) is a real possibility. Rasam has shown the presence of glycosides and flavonoids. Hence, a complete and thorough investigation is essential to understand the active ingredients formed during the process of preparing It is also wellknown that concentration of chemical constituents is directly proportional to its therapeutic/physiological effect.

CONCLUSION
The individual ingredients used in the preparation of the rasam are being claimed for various medicinal uses. Rasam is suggested as one of the general control measures of the SARS-CoV-2 by the Ministry of Ayush, Government of India.
No scientific details were available till date about the physical and chemical properties of rasam.
These properties are generally studied as part of pre-formulation studies. Understanding these properties of rasam would provide appropriate information about the suitability of rasam in formulation designing and development of dosage forms like conventional and/or novel drug delivery systems.

CONSENT
It is not applicable.

ETHICAL APPROVAL
It is not applicable.