Kopi Luwak civets choose which cherries to eat – i.e. those that are most ripe and flawless. Digestive mechanisms may improve the flavor profile of the coffee beans that have been eaten. The civet eats the cherries for the fleshy pulp, then in the digestive tract, fermentation occurs. The civet's protease enzymes seep into the beans, making shorter peptides and more free amino acids. Early production began when beans were gathered in the wild from where a civet would defecate as a means to mark its territory. On farms, civets are either caged or allowed to roam within defined boundaries. Coffee berries
Metabolic waste excreta. Some mammals including humans excrete uric acid as a component of their urine but it is only a small amount. These compounds form during the catabolism of carbohydrates and lipids in condensation reactions, and in some other metabolic reactions of the amino acids. Oxygen is produced by plants and some bacteria in photosynthesis, while CO is a waste product of all animals and plants. Nitrogen gases are produced by denitrifying bacteria and as a waste product, and bacteria for decaying yield ammonia, as do most invertebrates and vertebrates. Water is the only liquid waste from animals and photosynthesizing plants.