Food, as with all matter within the Matrix, was a program simulating reality by sending electrical signals directly to the human brain (that is, a person eating in the Matrix was given the full sensory impression that it was real food). In the Real World, food was of limited variety.
Simulated food in the Matrix gave humans the illusion of taste, smell, and nourishment. Even redpills who knew they were not actually digesting food still enjoyed the sensation of eating within the Matrix. However, specially coded food items were sometimes created that functioned as "power ups" within the Matrix.
Mouse observed to Neo after he was first freed that, having grown up in the Matrix, they had no way of knowing if the simulated foods in it like breakfast cereal or chicken were an accurate recreation of the real food's taste. As he put it, with no basis for comparison, for all they know the Machines could have made a mistake and "Tastee Wheat" cereal in the simulation actually tastes like real-life tuna. Later, Agent Smith explains to Morpheus that after the failure of the Matrix Beta Versions, the "modern" Matrix was redesigned with the goal of being as accurate to reality as possible. This means that basic details like the taste of different foods are never intentionally different in the Matrix, though as Mouse pointed out this still means mistakes are possible.
For example, in the beta "Paradise" Matrix breakfast cereal could have tasted like juicy steak or lobster, because that simulation was designed to be as pleasant as possible. In the modern Matrix it is designed with the goal of tasting like a realistically bland, wheat-based cereal. This leaves open the possibility, however, that while the Machines were genuinely trying to simulate the electro-chemical brain signal of "wheat taste" they made a mistake resulting simulated cereal that actually tastes like real tuna.
Candy: The Oracle carried small, individually wrapped pieces of candy when outdoors and commented on how much she loved it. After changing her shell, she cited her love of candy as evidence that she was still the same entity.
Chicken: Mouse cited the common saying that different food tasted like chicken (i.e. how a lot of food items tasted "just like chicken") in connection with how the Machines were trying to downplay how everything tasted the same within the Matrix but, in reality, possibly just lacked the data to recreate real flavors within the Matrix.
A poster advertising Tastee Wheat in the subway.
Tastee Wheat: Mouse cited a brand name of a healthy-sounding snack as an example of how the Machines may have gotten sensory specifics incorrect (he reasoned there was no guarantee that the taste of Tastee Wheat was right). Geoffrey originally theorized the same during the early years of Zion. A poster advertising Tastee Wheat is seen in the subway during The Matrix Revolutions, revealing that the brand's tagline is "Everything your body needs..." (which is what Dozer said about their goop food in the first movie).
Cookie: The Oracle frequently baked cookies while at her apartment home. On different occasions, she alternately offered her associates the pleasure of assisting with their preparation and the finished product as a comfort food.
Steak: Freeway billboards advertised "STEAK" to passersby. Cypher comments on how thoroughly he enjoyed the steak he was eating during his secret meeting with Agent Smith.
Noodles: Upon his return to the Matrix for the first time following his extraction, Neo pointed out an eatery that served noodles he was particularly fond of. He bemoaned how he will always have the false memories.
Orgasm cake: At Le Vrai restaurant, The Merovingian sent a custom-programmed dessert to a female patron. Visually, it appeared to be an innocent slice of gourmet chocolate cake. Upon consumption, hidden lines of code triggered a powerful orgasm within the woman. The Merovingian then furtively made himself available after she got up.
Forms of sustenance found in the Real World
The porridge in Zion
Protein-rich porridge or mush: This was the typical fare in Zion and on hovercrafts.[1] Its composition was given as a single-celled protein, vitamin, mineral, and amino acid colloid. Reviews were unfavorable due to its consistency and it was compared to runny eggs at best and a bowl of snot or puke at worst. Fungi, perhaps an ingredient, was abundant in the sunless surface.[2]
Bread: Wheat was once farmed by the farmers of Zion and they were able to stockpile grain before farming became a far too risky venture. Occasionally, bread was still made using the grain.[2]
Liquefied human remains: Sleeping humans in pods were intravenously force-fed the biological matter of the deceased in liquid form, as produced by liquefaction facilities.[2]
Small game meat: Small creatures such as ducks, frogs, and slugs[2] inherited parts of the surface left alone by the Machines. But these animals were living in the surface and too far away from Zion that Zion were unable to practically hunt them.
Rats, mice, and cockroaches: These smaller, more resilient life-forms were also found near the surface but were not normally viewed nor utilized as food by Zion.[3]
↑ 2.02.12.22.3The Miller's Tale, the story mentions all kinds of life still existing in very distant places, mentions how Zion baked bread, and how the dead were liquefied
