Polystarch

Polystarch was a type of instant bread that was included in some military rations. It was made by mixing a brownish flour with water in a container. A brief stir caused a chemical reaction, prompting the mixture to rapidly expand and solidify into a doughy loaf.

Behind the scenes
The instant bread effect in The Force Awakens was done practically. Special effects supervisor Chris Corbould said "You wouldn’t believe how long it took to actually perfect that one, that little tiny gag in the film." Said bread, however, tasted terrible and probably had next to no real nutritional value.

Appearances

 * Star Wars: Episode VII The Force Awakens
 * Star Wars: Episode VII The Force Awakens novelization