Palm sugar is the sweet substance that is processed from the sap of plant species belonging to the family Arecaceae or Palmae. The main product, a crude sugar that is also referred to by various terms such as jaggery, palm gur and muscovado sugar, is largely used for sweetening purposes. This information is nothing new, except that the advent of sugarcane and sugar beet as commercial sources of sugar has tended to put so much awareness on these sugar crops. The distribution of palms also favors the tropical world. Nevertheless, according to Hill (1972), the juice of some palms ranks as the fourth source of commercial sugar.
The raw material which is the plant sap, often called toddy, is extruded mostly through the inflorescence or through the terminal bud. The sweet sap is harvested through special technique called tapping. The processing of the sap into brownish sugar essentially involves boiling the sap in slow fire with continuous stirring to vaporize the water content.
However, the crude palm sugar is not the only product from the sap. The harvested sap has varied uses both traditionally and potentially such as fresh juice or for the manufacture of fermented drink, syrup, vinegar, wine, and refined sugar. More recently, its potential as a source of high-energy feed for livestocks has been emphasized, primarily through two review papers on tapping of palms for sap authored by Christophe Dalibard (1997; 1999). These two papers also supplied a comprehensive review on the traditional uses of the palm sap. Visitors are hereby advised to read the listed references.
Accordingly, sugarcane can produce 5-15 tons of sugar in every hectare per year, but areca nut, Asian palmyra palm, coconut and nipa palm can produce as much as 20 tons/ha of palm sugar per year. Depending on species and individual trees, the sap from most tapped palms contains 10-20% sugar while maple tree only contains 3%.
Data presented by Dalibard (1999) show that sucrose content in the sap of Asian palmyra palm (Borrassus flabellifer) was 8.5% to 12.3%. After cooking, it yielded jaggery with 76.86% sucrose. The author also cited sources stating that 100 liters of sap yielded 7-8 kg of sugar.
The potential of palm sap as a source of energy is also high. According to Hamilton and Murphy (1988) cited by Dalibard (1999), a hectare of nipa palm can yield 6,480-15,600 li/yr; coconut 5,000 li/yr of alcohol. In comparison, the alcohol yields from sugarcane and cassava are 3,350-6,700 and 3,240-8,640 liters per year in one hectare, respectively. Alcohol is used as a fuel additive for automobiles.
However, the processing of palm sap to sugar by heat requires high expenditure of energy. A large volume of fuel would be needed. This is a concern that demands more attention. In addition, it appears that the highly laborious tapping methods need to be improved. Other constraints have been identified.
DALIBARD C. 1997. The potential of tapping palm trees for animal production. Retrieved December 17, 2011 from http://www.fao.org/ag/againfo/resources/documents/frg/conf96htm/dalibard.htm.
DALIBARD C. 1999. Overall view on the tradition of tapping palm trees and prospects for animal production. Livestock Research for Rural Development. Vol. 11, No. 1. Retrieved December 17, 2011 from http://www.lrrd.org/lrrd11/1/dali111.htm.
HILL AF. 1972. Economic Botany. TMH ed. New Delhi: Tata McGraw-Hill Publishing Company. p. 210-241.
(Ben G. Bareja December 2011)