Standardization and Chemical Analysis of Rasam : A South Indian Traditional Functional Food

Cite this article : Devarajan A, Raja MK. Standardization and chemical analysis of Rasam: A South Indian traditional functional food. Pharmacognosy Journal. 2017;9(5):587-93. ABSTRACT Objective: The traditional Indian food is “functional” as it contains high amounts of dietary fiber, antioxidants, and probiotics. Rasam is a South Indian traditional spice soup. Spices are reputed to possess several pharmacological properties. Due to geographical, ethnical, and traditional differences, rasam recipe and the preparation process have a wide difference. Hence, the objective was to standardize rasam and then to perform a chemical analysis so that its pharmaceutical potential beyond nutritive effect can be explored. Materials and Methods: The quantity of ingredients and the process followed for preparing rasam by the 17 volunteers selected from in and around Vellore, Tamil Nadu was standardized. The proximate, nutritive, elemental, and phytochemical analysis were determined for the standardized rasam. Results: The total ash, acid insoluble ash, water soluble ash, and sulfated ash were found to be 1.7%, 0.04%, 0.12%, and 1.86%, respectively. The extractive values such as water soluble, ethanol soluble, and ether soluble were found to be 4.5%, 3.93%, and 0.61%, respectively. The standardized rasam showed very low-energy content of 15.13 kcal/100 g. Rasam contained alkaloids, tannins, saponins, flavonoids, terpenoids, steroids, glycosides. and volatile oil. Conclusion: The ingredients used in the preparation of rasam are medicinally claimed for various ailments, which makes it a traditional functional food. The standardized procedure provided tremendous opportunity to study the pharmaceutical potential in a systematic scientific way beyond its culinary and nutritive effect.


INTRODUCTION
The traditional Indian food is "functional" as it contains high amounts of dietary fiber (whole grains and vegetables), antioxidants (spices, fruits, and vegetables), and probiotics (curds and fermented batter products). Due to the chemical diversification of the ingredients, these Indian traditional functional foods exhibit the synergistic physiological effect. Epidemiological randomized clinical trials carried out in different countries have demonstrated numerous health effects related to functional food consumption such as 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, anti-inflammatory effects, reduction of blood pressure, maintenance of vision, antibacterial effect, antiviral effect, reduction of osteoporosis, and anti-obese effect. 1 Sambar, a South Indian traditional dish, has shown preventive effect against colon cancer. 2 Rasam, also called as chaaru or saaru, is a South Indian traditional spice soup, consumed especially in Tamil Nadu. Spices are used as flavoring agents throughout the world. In addition, they are reputed to possess several medicinal and pharmacological properties. 3 It is traditionally prepared using tamarind juice as a base, with the addition of Indian sesame oil, turmeric, tomato, chili pepper, pepper, garlic, cumin, curry leaves, mustard, coriander, asafoetida, sea salt, and water. Rasam is a functional food since all the ingredients used in the preparation are medicinally claimed for various ailments.
In India, traditional foods are filled with multiples of uniqueness that are specific to each region. Similarly, the preparation process of rasam has a wide difference due to geographical, ethnical, and traditional variations exist in the ingredients used its quantity. There are more than 20 different types of rasam based on the permutation and combination of its constituent spices. 4 Various literatures cite rasam as an effective treatment for cold, fever, flu, and diabetes 3,5 but rasam used in those studies were consistent neither in their ingredients nor in the process of preparation. To explore the pharmaceutical potential of rasam beyond its culinary and nutritive effect, there arised a need to standardize the ingredients used, their quantity, and process involved in the preparation of rasam. Hence, the study was planned to standardize rasam prepared in and around a particular geographical location, Vellore, Tamil Nadu, India, and also to per-form a chemical analysis so that its pharmaceutical potential can be consistently explored in a scientific way.

Location
Approximately 33 km in and around Vellore in four directions East, West, North, and South were set as zone of distribution for the study. Vellore was selected as a center of distribution (CoD). Around Vellore, 17 places (four in each direction) were selected. Seventeen volunteers one from each selected place were chosen as samples for studying the process involved in the preparation of rasam based on the following criterions; Females above 50 years Natives to the region for at least three generations, and Vegetarians.

Standardization
The quantity of ingredients and the process used for the preparation of rasam by the 17 volunteers were partially optimized. All the 17 volunteers were provided with the sufficient quantity of ingredients (q.s.) and utensils to prepare a fixed volume (500 mL) of rasam in their traditional way. The ingredients were purchased from Arokya Organic Shop, Vellore. All utensils used for the preparation of rasam were of stainless steel of 316 grade. The whole processes of the preparation of rasam were divided into five different stages as stepwise standardization; The data regarding the accurate quantity of the ingredients used and the exact processes followed by the 17 volunteers in the preparation of rasam were individually recorded as phase wise, and standardized to a fixed recipe with a precise process. Statistical analysis was performed using GraphPad Instat Version 4 software, and the values were expressed as mean ± standard deviation.

Proximate analysis of standardized rasam
The standardized rasam was subjected to proximate analysis such as total ash, acid insoluble ash, water soluble ash, sulfated ash, water-soluble extractive, ethanol soluble extractive, and ether soluble extractive values. 6 Nutritive and elemental analysis of standardized rasam The quantity of water, carbohydrates, proteins, fats, fibers, and vitamins present in standardized rasam was estimated. Moreover, the quantity of calcium, magnesium, sodium, potassium, phosphorus, sulfur, chloride, iron, molybdenum, boron, copper, manganese, zinc, nickel, aluminum, and selenium present in standardized rasam were also estimated. [7][8][9][10][11] Preliminary qualitative phytochemical analysis of standardized rasam The standardized rasam was studied for the presence and absence of secondary metabolites such as alkaloids, tannins, saponins, flavonoids, terpenoids, steroids, glycosides, and volatile oil. 12

RESULTS
The details of the selected 17 places, its coordinates, direction, and distance from the CoD are as shown in Table 1. The biological source of ingredients used for the preparation of rasam is as shown in Table 2. The  quantity of ingredients and the processes used for the preparation of T1,  T2, T3, T4, and T5 by 17 volunteers is as shown in Tables 3-5. The procedure for standardized rasam is as follows; T1 -6.88 g of tamarind fruit pulp was immersed in 450 mL of water for 10 min which was then hand crushed for 45 times and strained. The strained liquid was rinsed with 5 mL water into which 0.4 g of turmeric powder and 4 g of sea salt was added. T2 -82.44 g of fresh tomato fruits was hand crushed for 60 times. The crushed fruit was rinsed with 5 mL of water. T3 -1.33 g of pepper drupes was crushed in a mortar and pestle for 85 times. 2.67 g of cumin fruits was added over to the crushed pepper drupes and crushed for 100 times. To the above-crushed mixture, 0.82 g of chili pepper was added and crushed for 50 times. To the above mixture, 9.63 g of garlic cloves was added and crushed for 90 times. T4 -Tomato fruit mixture (T2) was rinsed with 10 mL of water, and spice mixture (T3) was rinsed with 10 mL of water. Both rinsing were added to tamarind fruit pulp mixture (T1). T5 -4 mL of Indian sesame oil was heated at 60°C for 2 min. After 5 s, 0.82 g of mustard seeds were added. After 3 s, 1.53 g of whole chili pepper was added. After 2 s, 0.61 g of curry leaves was added. Immediately, all mixture (T4) was rinsed with 20 mL of water and added. The whole liquid was allowed to boil for a 5 min. After 5 min, 1.50 g of coriander leaves was added. When the liquid frothed, 0.05 g of asafoetida was added, and the heating was switched off to yield the final product.
The ash values of standardized rasam such as total ash, acid insoluble ash, water soluble ash, and sulfated ash were found to be 1.7%, 0.04%, 0.12%, and 1.86% w/w, respectively. The extractive values such as water soluble, ethanol soluble, and ether soluble were found to be 4.5%, 3.93% and 0.61% w/w, respectively. The nutritional value of standardized rasam per 100 g is expressed in Table 6. Preliminary qualitative phytochemical analysis of standardized rasam results confirmed the presence of alkaloids, tannins, saponins, flavanoids, terpenoids, steroids, glycosides, and volatile oil.

DISCUSSION
The traditional foods of each specific region of India are primarily a component of its culture. If these traditional foods are to be standardized, it has to be evaluated within a specific region. Hence, a specific geographical location Vellore, Tamil Nadu was selected to standardize rasam. For better efficiency of the standardization process, 17 volunteers were selected based on specific criterions within the selected geographical zone. The required ingredients and the necessary utensils were provided to all 17 volunteers to maintain uniformity of the study. The 17 preparations from each volunteer were qualitatively and quantitatively recorded in phase wise. The quantity of ingredients and the processes followed by the 17 volunteers involved in the preparation of rasam were combined and standardized to a fixed recipe. Based on the derived recipe, a standardized rasam was prepared and further subjected to chemical analysis. Ash values identified the presence of inorganic radicals such as carbonates, phosphates, silicates and silica of sodium, potassium, magnesium, and calcium. Total ash and sulfated ash of the standardized rasam indicated high quantity of carbonates and oxides. Inorganic variables such as calcium oxalate, silica, carbonate content affected the "total ash" values. Such variables were removed by the acid treatment (as they are soluble in hydrochloric acid) and then acid-insoluble ash value was determined.  Low acid insoluble ash indicated less silicious materials such as earth or sand. Extractive values are useful as an evaluation tool to provide an idea about the nature of the chemical constituents present. Extractive values of standardized rasam showed very high quantity of polar and moderately polar constituents than nonpolar constituents. Rasam is used as an appetizer, and its ingredients such as tamarind, turmeric, cumin, black pepper, curry leaves, and asafoetida are known for their digestive aid activity. There are various foods that create a neg-ative-calorie effect, which improves metabolism. These foods are usually plant-derived which are high in water content, rich in fibers, grains, legumes, vegetables, and fruits. A negative-calorie food is a food that requires more energy to digest the food than it provides. Standardized rasam almost contained water (95.03%) with only 15.13 kcal. Hence, the body has to burn more energy to digest than it receives. However, there is no substantial evidence to comprehensively prove that rasam has negative calorie effect.
Pharmacognosy Journal, Vol 9, Issue 5, Sep-Oct, 2017   The altered/different chemical composition of the rasam may be due to the loss of active principles or synergetic effect or breakdown of inactive metabolite to an active one or formation of new chemical entities. In the era of preventive medicines, a standardized procedure for the preparation of rasam can aid the exploration of its pharmaceutical potential in a systematic scientific way beyond its culinary and nutritive effect.

CONCLUSION
The processing followed in the formulation of rasam involved heating the spices in water and oil. This processing provided tremendous opportunity for a completely altered/different chemical composition of rasam.