Throughout the evolution of mankind and civilization, rasa played a vital role in developing cognitive features and continues to do so. Rasas add much needed aesthetics to one’s otherwise mundane existence, explores Dr. Pratyush Mishra

How about a glass of ripe mango juice with one or two cubes of ice thrown in to ward off the simmering summer heat that scorches the body, mind and spirit! Or, may be a glass of cool lassi, or may be, a glass of pineapple juice? When we talk about juice , we are essentially talking about Rasa that rules the domain of taste.
Just imagine if we have to eat food that carries only one taste day in day out, throughout our existence! Say, if all the foods we eat tasted only sweet! Or Salty, or Sour, or just bland! We simply cannot imagine such a life. But the nature provides us from her bounty a wide range of food produces having different taste and flavor. And fortunately, the foods we eat tick many boxes of taste: sweet, salty, sour, bitter, pungent and astringent that fall within the ambit of what we call sada rasa.
The reference to rasa goes back to the Rig Veda where it was used to denote as a river by the same name as well as an all pervading cosmic consciousness and the essence of the Soma. “raso vai sah rasam hy evayam labdhvanandi bhavati,” declares Taittriyya Upanishad. Here,  rasa refers both to the taste, to the essence, to a self-luminous consciousness, the quintessence. Thus, rasa is an aesthetic amalgam of all visual, auditory and gustatory stimuli that evokes a range of emotions and leads to transcendental experiences. Hence, ancient knowledge systems expounded that everything has rasa as that subtle principle which imbues meaning into the way we experience life as a force, and make meaning out of our day to day mundane living. 
The origin of the water element is the tanmatra of taste called rasa. Rasa in this context is the primordial causation of the experience of taste. Rasa tanmatra is the causal energy that provides the potential for the experience of taste to occur. It is not the taste in itself. However, since taste depends upon the water element for its manifestation, disorders of the ability to taste are due to an imbalance of the water element.

Sada Rasas

Sweet decreases Vata and Pitta, increases Kapha
The sweet taste is comprised of water and earth, and is good for balancing Vata and Pitta. Of the six tastes, sweet is known to be the most grounding and nourishing. It balances the burning sensation for Pitta and is good for health of skin and hair. When eaten in moderation, it promotes longevity, strength, and healthy bodily fluids and tissues. The sweet taste is prominent in foods such as wheat, rice, dairy, cereals, dates, pumpkins, maple syrup, sugar, potato and ghee and licorice root
Sour decreases Vata, increases Pitta and Kapha
The sour taste consists of water and fire. It stimulates appetite and saliva production, and is balancing in its light, heating, and oily properties. The sour taste awakens the thoughts and emotions, and can improve appetite, digestion, and elimination. of toxics from the body. However, if had in excess, it can cause indigestion, hyperacidity and ulcers. Some sour foods are lemon, vinegars, pickled and fermented foods, tamarind, yogurt, tomatoes, gooseberry, sea food, alcohol and wine.
Salty decreases Vata, increases Pitta and Kapha
The salty taste consists of earth and fire. It is best for Vata because of its grounding and hydrating nature. It adds taste to foods, stimulates digestion, helps electrolyte balance, cleanses tissues, and increases absorption of minerals. This rasa keeps the body warm, improves digestion and promotes growth in the body. If had in excess however, it results in sluggish lymphatic drainage, thus causing water retention and hypertension. Examples of salty foods are sea vegetables, sea salt, table salt, rock salt, tamari, black olives and processed foods that contain salt. 
Pungent increases Vata and Pitta, decreases Kapha
Fire and air make up the pungent taste. Pungent food is the hottest of all the rasas, and therefore stimulates digestion, improves appetite, clears sinuses, stimulates blood circulation, and heightens the senses. Pungent food may help you think quickly and clearly, and make understand complicated matters more easily. This helps in breaking down fat, aids digestion and absorption, and activates blood circulation. In excess, it can cause stomach irritation, heart burn and nausea. Some examples of pungent food: hot peppers, ginger, onions, chili, garlic, mustard, and hot spices.
Bitter increases Vata, decreases Pitta and Kapha
Bitter taste consists of air and space. It’s considered the coolest and lightest of all the tastes. Because of its cool qualities, it’s highly detoxifying and can help remove waste products from the body. Bitter foods also help mental purification by freeing you from passions and sultry emotions. This rasa enhances liver function and muscle tone. It’s best for Pitta, good for Kapha, and least beneficial for Vata. Among bitter foods are raw green vegetables, turmeric, and green, black, Neem, bitter gourd, spinach and most herbal teas belong to this rasa.
Astringent increases Vata, decreases Pitta and Kapha
The astringent taste is made up of air and earth. It’s cool, dry, and firm. Pitta benefits most from astringent taste’s coolness, and its dry, light attributes balance Kapha. It has anti-inflammatory properties and helps in absorption of nutrients and is very cooling to the stomach. In excess, it can cause constipation.  Many beans and legumes are astringent and can cause gas, which is why it should be ate in moderation. Like bitter food, astringent food will help mentally purify and strengthen you.Unripe bananas, green grapes, pomegranates, cranberries, green beans, alfalfa sprouts, and okra, Tea, coffee, pomegranate, asparagus, cauliflower and figs are all astringent foods.

Hot and humid summer affects body mechanism by bringing imbalance to the Pitta, which constitutes fire element and is the functional mechanism behind digestion and metabolism. The dry climate also becomes the harbinger of secondary Vata dosha, means imbalance of the air element. Our bodies inherently crave light and easily digestible foods, often in small quantity. Savoring the taste and flavor receives great importance. Tastants are the chemical substances that interact with taste receptors in our tongue and generate a discriminative sensory response. What and how we enjoy that sensory experience forms a part of the pleasure, our hedonic response. Avoiding certain foods by individuals is often linked to sensory characteristics of the food itself. Combination of food and smell together gives rise to flavours.  Cognitive neuroscience states that flavours, which are a rich sensory experience, are a side effect of deeply adaptive learning or the learning of our species motivated by incentives. Thus, Taste is both rewarding and punishing like the two sides of the ame coin which motivates our learning and cognitive experiences. We can surely observe that the pattern of feed-fatten-please-replenish-repulse can never leave the human behavior unaffected. The ancient masters and elders who researched on various dimensions of practical living and healing coined the concept called Rasa. 
Rasa lies in experiencing and replicating the experience inter-individually. In the realm of taste., it very well refers to the totality of experience arising from all perceptory interaction with sensors in mouth and taste bud, which are called Chemaesthetic receptors. Charaka went ahead to state that rasa is experienced the moment it comes in contact with the tongue, any other perception which occurs after that is termed “Anu-rasa”.
Dravyaguna means the potency of ingredient which is an inherent part of Ayurveda and Siddha healing systems as well as many indigenous fringe healing systems that utilize rasa of substances as its primary tool to assess their pharmacological behavior. The inherent rasa in ingredients are considered to be the manifestation of the panchamahabhutas, thus indicating the structure and activity of the functioning substance. When a rasa is in an activated state, it is called Utkarsa. Rasa is defined as the knowledge perceived through Rasanaa Indriya on the Jihva or tongue- the gustatory sensation.
Indian ancient healing systems hint at sada-rasa which are six basic tastes: sweet (madhura) , sour (amla), salt (lavana),  pungent (katu), Bitter (Tikta)  and astringent (kashaya). It is considered to be a tremendously important therapeutic tool which extends its roots into domains of healing, wellness as well as cognitive psychological processes. Rasa is critically important in determining effects of substances ingested, on various foods, herbs and spices on our state of being- body mind and spirit. Taste is a living representation of experience which must be wholly acknowledged, relished and appreciated for its beneficence. Same substance can taste differently depending on where it is grown, raised, harvested, stored and processed. Thus, elementary beginnings of the sada-rasa give way to a mosaic of effects. Some can be pacifying to the tri-dosha, while others can aggravate them. Some rasas have cooling effect, while others can generate heat. Vipaka aspect deals with the post digestive effects like absorptions, metabolism and elimination. Prabhava signifies the unique action a singular substance can generate within the body, which also extends to Gunas or attributes and emotional influences as well. For example, sweet taste proves to be grounding and nourishing during the summers. It benefits the mucus membranes of the body by balancing vata (dryness) and pitta; however, it raises the kapha dosha. It is nutritive, acts by energizing the body and soothing the mental affects which in turn enhances clarity of thought.
All perceptions are psychological processes which try and make sense of the stimuli. In short, real world information is converted into electrical stimuli which internalizes the experience. Thus, rasa cannot be delinked from inner and innate bio-electrical processes within the body which in turn affects behavior, activity and personality of an individual. Yet, the fundamentals of taste go way back into our evolutionary moorings. Many animals and mammals indulge in gapes and licks which reflect the animal’s desires to have less or more of the substance. It informs about the preferences.
Often we deliberately choose to have a unique taste experience and take the substance that we wish to consume in appropriate surroundings. What we see, smell and hear also affects our appetite and experience. The most interesting dimension of the taste percept is that we experience it after sending that substance down towards our stomach for digestion and assimilation. Taste quality are inherently attuned to identifying specific nutrients, ensuring energy reserves and maintaining water balance. Specific needs of the body and inclination of personality linked to satiety or sense of fullness dictates whether we consume more of the specific substance or are repulsed by the sight of others. Hence, taste driven neural activity and behaviors are intrinsically value added. Our dopamine system is specifically involved in tagging taste experiences and stimuli as rewards. Increasing interest in the hedonic aspect of taste has made groundbreaking furrows in consumer behavior.
All of us go through the influence various rasas at some point of time during a day. Depending upon our temperament, epigenetics and constitution of body, certain rasas dominate the individual personality. Rasas are intricately connected to Bhava or the quantum of emotion-knowledge-value purports that dictate our relating with our environment. Feeling is the awareness of the affect while emotion is the subjective experience of the affect. Though Rasas are definite principles, yet, resultant emotions can manifest in context to cultural and personal backgrounds. Deficit in rasas can be cultivated by inculcating habits, consciously enjoying the senses through food, music, movement aesthetics, ingestion of food and herbs. By this, overwhelming feelings and traits can be used for self-transformation.
Taste along with other senses or modalities together gives rise to a super-additive effect that integrates many sensory inputs. This in turn generates taste preferences. Taste preferences can be studied to assess inherent personality traits of an individual. It is seen that individuals who prefer more salty foods are more extraverted and open to life experiences while those who are inclined towards bitter substances can have highly self-serving, narcissistic and elevated pain thresholds. Individuals who have very narrow range of taste preferences, tend to be finicky and anxious in day to day living.
Understanding the relationship between the rasas and how they can be interconnected and generate symmetrical personality and lifestyle is very important. Rasas are strongly related to relationship and relationship management. For example, between a couple the quality as well as the quantity of emotions, , combined with the pursuit of adding  aesthetic values into their relationship can only happen if they can relate to each other’s personality with manifestation or deficit of rasas. Yoga-Tantra system, which is a life encompassing discipline with deep roots in indigenous applied philosophy, approaches to resolving conflicts within own personality through balancing and elevating the pancha-tanmatras are related to the sensory organs as well as the Panchamahabhutas. Without being excessively exotic and esoteric, techniques which are practicable in day to day living are applied. These do not require delinking oneself from the society nor reduce the interaction with own surrounding.

aying attention to the rising in anger within own self and defining the triggering stimuli can not only help assuage it but also delay it. 
The physiological component of emotions emerges by external stimuli as well as the interplay of reflexes and interplay of neurotransmitters which are the information molecules. Neurotransmitters like acetylcholine influences the concentration; fear and alertness are linked to dopamine; joy and love to endorphins; GABA linked to nervousness and anxiety; while oxytocin is linked to orgasm satiety and love. Serotonnin, also known as the happiness neuro-hormone, influences inner peace, and deficit of it plays a role in depression.
Foods directly promote rasas by affecting energy levels of an individual, subsequently, affecting emotions, moods and personality at larger scenarios and scales. The amygdale and hippocampus which are parts of the limbic system are together called as the emotional brain of the human nervous system. It helps in formation and retrieval of memories, controls decision making, motivation and intrinsic desires and learning. Even modern advances in neuroscience have linked the gut to emotional health.
As individuals, we continuously try to make sense of our perceptual realities which in turn changes our neuronal connects and patterns that can generate newer patterns of emotions. Rasas help deal with the conscious transition of these emotional, neural and biochemical patterns. Taste like sight and fragrance can trigger agreeable or disagreeable expressions of personality traits and memories. Not only the ingredient of foods but the way they are cooked affects the rasas. Rasas can extend into sleeping patterns or their disruptions such as sweeter foods or starchy foods inducing sleep. The kind of exercise one prefers or doesn’t wish to exercise at all is linked to predominant gunas which are influenced by rasas. It can even percolate to our social lives and decisions like whether an individual values hobbies or not, and if so, what kind of hobbies one prefers. Changing the body chemistry during unwanted emotional emergencies can reorient the individual to move into a better mode of response, like taking cold showers if one is angry, taking sour and astringent foods during states of acute fear, or drinking fresh fruit juices which can help contend with feelings of disgust. It is a noted behavior pattern that during episodes of emotional stress, individuals tend to eat their comfort foods
Dominant elements in Rasas are water in love, courage sadness and disgust; fire in joy, wonder and anger; and air in fear and calmness. Disturbed doshas can also be linked to Rasas- pitta is raised in anger, vata in fear, and kapha in sadness and disgust. For a person with pitta preponderance, anger will need just a tiny spark to be ignited and go overboard. Perfectly balanced Vata can induce calmness but disturbed Vata can lead to extreme paranoia, shame and exaggerated fear.
The past few decades have witnessed a consolidation and refinement in taste research. Newer data has emerged in cellular mechanisms for detecting taste and also transmitters involved in taste processing – Serotonin, Calcium channels, GABA and glutamate. Taste buds are peripheral organs of gestation embedded in epithelium of tongue, palate and epiglottis. These chemo-sensitive receptors in the apical tips confer specificity to the gustatory stimuli. These help in sampling the chemical makeup of the foods and beverages for nutrient content, palatability and potential for toxicity. Molecular recognition of tastants results ultimately in sensory perception. Most cells express a taste receptor namely Type1 or Type 2 which correspondingly respond to one taste quality. They may be stimulated by other stimuli on a secondary basis. Bitter , sweet and umami stimuli are detected by type 2 cells, sour by Type 3 cells and salty by yet to be defined receptors.
There are also extra oral taste receptors primarily of Type 2 and some Type1 receptors which are spread all over the body apart from the tongue and oral cavity like regions of brain, heart, airways , intestine, stomach and pancreas. A less tangible food related sensation was found in 1990 by Sakaguchi Etal termed as kokumi. Substances like peptides and glutathione are principal kokumi stimuli. Taste coding exists in complex and intricate way within the central nervous pathways.
India’s ancient knowledge on food prescribed to include six rasas in the daily food. The meal in a traditional India Thali would have rice, lentils (dal), vegetable dishes, roti, salad, chutney or pickle and a sweet dish. Throughout the evolution of mankind and civilization, Rasas played vital roles in developing cognitive features and continues to do so. Rasas add much needed aesthetics to one’s otherwise mundane existence.