Understanding the Science Behind Cashew Feni

by Nandkumar Kamat
Posted on 2009-01-13
Thanks to public private; government, industry and academicians partnership, very soon Goa’s unique Cashew feni may get the status of Geographically indicated products under India’s GIP Act and the demanding WTO export regime. The process is in final phase. Having worked as a member of the committee on this mission, and as scientist researching the microbiology and biochemistry of cashew fermentation, GIP for feni is a milestone for us.
Goa produces two types of Feni - the Cashew and the Palm. From Cashew three grades of liquor are produced Uraq, Cazulo and Feni. Uraq is the product of first distillation, Cazulo the second and Feni, the third. Cazulo is not made now so Feni is produced after second distillation. Uraq contains 40 per cent (14-15 deg) and Feni 75 per cent alcohol (18-20 deg). There is an elaborate procedure for distillation of feni. We have done some research at Goa University with the help of agriculture department on understanding the chemical and biochemical composition of different varieties of cashew in Goa.
There is no specific hybrid strain, which can be exclusively recommended for producing juice. The general observation is that the yellow variety of cashew apples gives more juice. Juice from different cultivars may differ in composition of total sugars. We are aiming to identify, define and validate the raw material for Feni production. As regards crushing and extraction of juice - in unorganised, traditional sector, the crushing is still crude and may not result in good juice recovery. We are trying to decipher the exact sequence of primary fermentation in terms of microfloral succession.
Tentative calculations show that considering 26.5 per cent total sugar content in the dry matter, for a litre of feni 1.79 kg of sugars would be required yielding 33.5 per cent alcohol by weight. The boiling process needs standardisation. Volatiles with different boiling point therefore can get mixed. Control of temperature and its duration is important. Primary distillation produces Uraq which appears to be a mixture of lower distillates with some flavour compounds.
There are some interesting facts about feni production. 35 kg of cashew apples give one tin of juice equal to 4 gallons. Two kg of apples give a litre of juice. Two to three days are required for fermenting the juice. 20 litre fermented juice is used at a time to produce 14-15 litres Uraq. Uraq is mixed with fermented juice in 1 to 2 ratio to produce Feni. A mixture of 30 litres of Uraq and 60 litres of juice produces 14-15 litres of Feni. Fermented juice gives 15 per cent Uraq and 6.5 per cent feni. To get a litre of Uraq, 12 kg of Cashew apples are required. To get a litre of Feni, 30 kg of Cashew apples are required, equivalent to 15 litres juice(=1.79 kg sugar). The distillation time for 15 litre of liquour is 3-5 hours. Uraq contains 40 per cent (14-15 deg) and Feni 75 per cent alcohol (18-20 deg). Most important - The quality of the Feni depends on distillation time. The secret of feni quality lies in distillation time. Slow distillation produces Feni of better quality, short distillation produces Feni with bitter quality.
The chemical composition of the cashew apple juice may vary. That could be the chemical basis of the typical strong aroma of feni? Garutti and his team members in 2003 detected, Esters such as -methyl 3-methyl butanoate, ethyl 3-methyl butanoate, methyl butanoate, ethyl butanoate, ethyl trans-2-butenoate and methyl 3-methyl pentanoate which were important to the sweet, fruity and cashew-like aroma. A lot of research is still required to bring Goa’s feni to the level of Scotch whisky or French wines. After feni gets GIP the responsibility of government and manufacturers in organised and unorganised sector would increase. To make Goa’s feni the best Asian tropical distilled liquor and bring it on par with Mexican Tequila, emphasis has to be given on research, development and quality upgradation.
The government of Goa under its industrial policy and biotechnology policy needs to encourage basic and applied research in the microbiology, biochemistry, analytical chemistry and fermentation technology of feni production. Besides cashew feni the simple route to produce more valued cashew wine needs to be explored. GIP for feni needs to kick start the process of identification of other truly Goan products which could qualify for similar status.