**1. Introduction**

158 Distillation – Advances from Modeling to Applications

Meier, U., 2001. *Entwicklungsstadien mono- und dikotyler Pflanzen: BBCH Monografie.* 2.

*Cachaça* is the sugar cane spirit typical of and exclusively produced in Brazil which has alcohol content between 38 and 48% in volume, at 20oC. It is obtained from the sugar cane fermented wort and has peculiar sensory characteristics. It may also include the addition of up to 6g/L of various sugars, expressed as sucrose (Brasil, 2005).

In the production of *cachaças*, as of other distilled beverages, a distillation process is used to isolate, select and concentrate specific volatile components of the "liquid mixture" by heating it (Boza & Horii, 1988; Léauté, 1990). After the fermentation, the distillation is the most important step for the quality of distilled beverages (Janzantti, 2004; Boza & Horii, 1988).

Distillation also promotes some heat induced chemical reactions such as the synthesis of acrolein through a Maillard reaction (Boza & Horii, 1988 ; Nykänen & Nykänen, 1991) and of heterocyclic aromatic compounds, such as furans (furfural, etc.), pyrazines and pyridines (Janzantti, 2004 ; Léauté, 1990). Besides that, distillation causes the extraction of certain long chain esters retained in the yeast cells at the end of the fermentation step, transferring them to the distillates (Nykänen & Nykänen, 1991).

The *cachaças* "wine" composition is quite complex and contains liquid, solid and gaseous substances. Ethanol is the main liquid component, with 5 to 8% v/v, and water is the substance present in the greatest amount - about 89 to 92% v/v. Other liquid components present in smaller amounts are glycerol, lactic acid and butyric acid; volatile components such as esters, acetic acid, propanoic acid, aldehydes and higher alcohols, among others (Novaes, 1999; Bruno, 2006 ; Nascimento et al*.*, 1998a,b).

At every production of a distilled beverage, each volatile component will be more easily distilled according to three criteria: solubility in alcohol or water, boiling point and alcoholic content variation in the vapor phase during distillation (Janzantti, 2004 ; Léauté, 1990).

According to the components' volatility, it is possible to isolate the volatile (water, ethanol and others) components from the non-volatile ones (suspended solids, minerals, yeast cells, non-fermentable sugars, proteins, etc.) obtaining two fractions, phlegm and vinasses, the residue from the distillation of the "wine". The phlegm, main distillation product, is an

Distillation of Brazilian Sugar Cane Spirits (Cachaças) 161

Fig. 1. Common Alembic (Source: Nogueira & Venturuni Filho, 2005)

around 45 - 50% vol in the receiving box and then the "cut" is made.

completed.

Besides that, a gradual temperature increase allows the production of vapors which, upon reaching the column head, will partially condense and return to the kettle. The porting of uncondensed vapor reaches the extension tube and partially condenses when becomes in contact with a colder surface. Then it reaches the cooler, where the condensation is

The distillate shows a high alcoholic content (65 - 70% vol) at the beginning of the process and a separation of 5 -10% of the total theoretical volume of spirit by the initial distillation is recommended. This is known as the "head" distillate, rich in aldehydes, ethyl acetate, fatty acids, ethyl caprate and ethyl caprylate (Léauté, 1990; , Mutton & Mutton, 2002; Bruno, 2007), dymethil sulphide (Nicol; Faria et al., 2003) and other volatile compounds that have greater affinity for ethanol than for water, a factor of greater significance than the individual boiling temperatures (Maia, 2000; Leauté, 1990). The fraction known as "heart distillate", the core distillate, is isolated next and contains a smaller proportion of the "head fraction" components, such as esters, aldehydes, higher alcohols, besides ethyl lactate and the fraction of long chain volatile acids and other undesirable secondary products in concentrations higher than those recommended, formed during the fermentation or inside the alembic itself (Janzantti, 2004 ; Léauté, 1990 ; Mutton & Mutton , 2005). The "heart fraction" represents about 80% of the distillate volume. Since it contains the smallest amount of undesirable substances, this is the best fraction. In practice, usually the phlegm content is controlled

Finally, the components with higher boiling points and greater affinity for water are removed. This fraction ("tail") has a high content of phurphural and of other less desirable

impure hydroalcoholic mixture, and its content depends on the type of equipment used (Mutton & Mutton, 2005).
