Trupti.

 Now that the annam (rice) is served, we can commence a prayer to sanctify the food we are eating, before we actually start eating,"  "In the Vedic tradition, every act becomes an act of worship and an act of recognition of the pervasiveness of the Supreme Brahman and Its power. Thus the act of eating is an act of thanksgiving to God, typically preceded by a prayer.

"The Hindu thanksgiving prayer is known as parisEshaNa mantra and is an important part of our bhojana vidhi. This prayer has a dual function: to offer all that we eat to God and his deputies who administer Nature; since these deputies are also present inside our bodily systems, the mantras chanted also regulate their functions.

"parisEsaNam means sprinkling water over and around the food  

meaning and philosophy behind this ritual.

 touch the tip of their plates with their left hand. They take some water from their pancha pAtram-uttaraNi (puja cup and small spoon) in the palm of their right hand and pour it through the fingers in drops around their leaf-plates saying the first line of the Gayatra Mantra: 'Aum bhUr bhuva suvahaH'.

Then they sprinkle a little water over the annam, saying the remaining three lines of the Gayatri Mantra: 'tat savitur vareNyam, bhargo devasya dhImahi, dhiyo yo naH prachodayAt'.

"The Gayatri Mantra is addressed to the Sun, the most visible of the gods. Since he is the giver of all food, we first invoke his blessings. Remember it is he who nourishes the agni, the fire and heat necessary for digesting food."

The elderly pandits once again encircle the food with the mantra 'satyam tvartena parishincAmi'. that this mantra means, 'O food, you are true and I encircle you with divine righteousness.' He says further that from 5 o' clock afternoon this mantra will be replaced by 'Rtam tvA satyena parishincAmi'.

Then they pour one uttaraNi of water onto their palms and sip it saying under their breath, 'amRuthOpastharaNamasi'. Grandpa says, "This mantra is actually to be recited within the mind. amRut ApaH upastaraNam asi: upastaraNam means the act of spreading out under as a substratum. I have invoked the little amount of water I sipped now to spread within me as Amrutam or nectar and form the substratum for the food to follow. Vishnu Purana says that liquid substances should be taken at the beginning and at the end of the meal."

 on the significance of drinking some water before and after food: "The Rishis have mentioned in the Upanishads* that realized people, while eating, before and after their meal, 'dress up' the prANa (breath of life) with water. You see, water is a purifier; it also sustains the body. Most Hindu rituals start with sipping water, an act known as Achamanam. The Yoga Shastras recommend that we should fill only half our stomach with food, a quarter with water and the rest should be air. This ideal proportion brings in spiritual and bodily health."

prANAhuti: offering to the vital breaths

 continues on the next act of the parisEsaNam: "After water, it is now the turn of the air or breath. Water nourishes the body to keep it healthy, but air in the form of life breath sustains the soul and holds it in the driver seat of this bodily vehicle. The life breath or prANa has five functions. prANa is the principal breath coursing through our nostrils and lungs; you can use it to control and regulate your mind and thoughts. apAna is responsible for the excretory activity. samAna circulates around the navel and plays a vital role in digestion. vyAna is diffused through the body and is responsible for circulatory activity. udAna is the wind that goes upward in respiration. These five vital airs together represent the Vaayu deity; they are also infused with agni or fire and Apas or water. Therefore we offer a morsel of annam as Ahuti to these gods, by swallowing the food without biting it. We don't bite it because it is not for personal consumption. Watch how we do it."

Using the thumb, middle and ring fingers of their right hand in a typical mudrA of a deer-head, pick a morsel of rice mixed with ghee and throw it straight into their mouth, keeping their heads down. For each such morsel they swallow they recite a line of mantra:

"aum prANAya svAhA | aum apAnAya svAhA | aum vyAnAya svAhA | aum udAnAya svAhA | aum samAnAya svAhA | aum bhrahmaNE svAhA |". Then they drop a little water on the left side, touch it with the ring finger of their left hand and then with that finger touch their chest, while chanting "aum brahmaNi ma AtmA-amRtatvAya".

"This last line of the mantra says, 'May the Self be united with Brahman so it may attain immortality'," "That completes the parisEsaNam prayer. We can now start eating."

tRupti bhojanam: a satisfactory meal

Some people say a simple prayer after circumbulating the food served with the palm filled with water.

Annam Brahma rasam vishnu.

Bogtham devo janardhana.

Aevam dyathva tatha gyathva.

Anna dosho na lipyate. 

The creative energy in the food is Brahma.

The nourishing energy in the body is Vishnu.

The transformation of food into pure Consciousness is Shiva.

If you know this, then any impurities in the food you eat will never become part of you.

A prayer or invocation offered before eating. The act of consuming food is considered to be a Yajna (sacrifice) and the offering goes to the divine authority called Jataragni, the digestive fire in the belly. It is that principle which breaks down the food consumed into a form that can be supplied to through the blood for the whole body. The creative energy in the food (Annam) is Brahma. The nourishing energy (Rasa) in the body is Vishnu. The transformation of food into pure consciousness is Shiva. If you know this, then any impurities in the food you eat will never become part of you.

This shlokam is chanted before eating food so that even while eating, our attention is focused on the food, and we eat it with an awareness of its importance.

While eating our food, we must utter the words, “Annam Brahma” (food is God); Raso Vishnuhu (the essence of food is Vishnu). Food is God. It gets into the body and provides its essence to all the parts of the body. It indeed gets transformed into blood and energy. Bhoktodevo Maheswarah (the one who consumes the food is Maheswarah). This principle teaches wisdom to the whole world. Annam Brahma, Raso Vishnuhu, Bhoktodevo Maheswarah –These three correspond to body, mind and action, respectively.
Manasyeka Vachasyekam Karmanyekam Mahatmanam
(those whose thoughts, words and deeds are in complete harmony are noble ones.)
The oneness of thought, word and deed is ritham.
They represent the Trinity of Brahma, Vishnu and Maheswara. Hence, everyone must strive for the purity of these three.

Purify the food by offering it to God.
Annam Brahma. Consider food as verily the form of Brahma.
Raso Vishnuhu. The essence of food that spreads to all parts of your body is Vishnu swarupa.
Bhokta devo Maheswarah. The partaker of food is the very embodiment of Siva principle. When man develops such sacred feelings, he becomes Siva Himself–