Kopi Luwak (Civet Coffee)

what makes Kopi Luwak recognizable and desirable?

Despite the different bean base and farming methods, the enzymes that are responsible for the creation of Kopi Luwak-style coffee are consistent in their effect upon the coffee. Thus, all Kopi Luwak is recognizable for certain tastes, aromas and characteristics, such as extremely low bitterness. The main characteristics are: Exceptionally pleasing initial aroma, generally lighter roast (due to the low bitterness and the enzyme structural action, heavy roasting is not needed to bring out more flavor), smooth, buttery mouthfeel, a hint of chocolate overtones, and a haunting persistance not just on the pallet but on the memory.

Kopi luwak, or civet coffee, is one of the world's most expensive and low-production coffee. It is made from the beans of coffee berries which have been eaten by the Asian Palm Civet (Paradoxurus hermaphroditus) and other related civets, then passed through its digestive tract. A civet eats the berries for their fleshy pulp. In its stomach, proteolytic enzymes seep into the beans, making shorter peptides and more free amino acids. Passing through a civet's intestines the beans are then defecated, keeping their shape. After gathering, thorough washing, sun drying, light roasting and brewing, these beans yield an aromatic coffee with much less bitterness, widely noted as the most expensive coffee in the world.
Kopi luwak is produced mainly on the islands of Sumatra, Java, Bali and Sulawesi in the Indonesian Archipelago, and also in the Philippines (where the product is called motit coffee in the Cordillera and kape alamid in Tagalog areas) and also in East Timor (where it is called kafé-laku). Weasel coffee is a loose English translation of its name cà phê Chồn in Vietnam, where popular, chemically simulated versions are also produced.

Cultivars, blends, and tastes.
Kopi luwak is a name for many specific cultivars and blends of arabica, robusta, liberica, excelsa or other beans eaten by civets, hence the taste can vary greatly. Nonetheless, kopi luwak coffees have a shared aroma profile and flavor characteristics, along with their lack of bitterness.
Kopi luwak tastes unlike heavy roasted coffees, since roasting levels range only from cinnamon color to medium, with little or no caramelization of sugars within the beans as happens with heavy roasting. Moreover, kopi luwaks which have very smooth profiles are most often given a lighter roast. Iced kopi luwak brews may bring out some flavors not found in other coffees.

Sumatra is the world's largest regional producer of kopi luwak. Sumatran civet coffee beans are mostly an early arabica variety cultivated in the Indonesian archipelago since the seventeenth century. Tagalog cafe alamid (or alamid cafe) comes from civets fed on a mixture of coffee beans and is sold in the Batangas region along with gift shops near airports in the Philippines

Research.
Several studies have examined the process in which the animal's stomach acids and enzymes digest the beans' covering and ferment the beans. Research by food scientist Massimo Marcone at the University of Guelph in Ontario, Canada showed that the civet's endogenous digestive secretions seep into the beans. These secretions carry proteolytic enzymes which break down the beans' proteins, yielding shorter peptides and more free amino acids. Since the flavor of coffee owes much to its proteins, there is a hypothesis that this shift in the numbers and kinds of proteins in beans after being swallowed by civets brings forth their unique flavor. The proteins are also involved in non-enzymatic Maillard browning reactions brought about later by roasting. Moreover, while inside a civet the beans begin to germinate by malting which also lowers their bitterness.At the outset of his research Marcone doubted the safety of kopi luwak.However, he found that after the thorough washing, levels of harmful organisms were insignificant. Roasting at high temperature has been cited as making the beans safer after washing. 
(article source: wikipedia ,  duoguelph.ca , trung nguyen coffee)