WHAT IS THE EFFICIENT INHIBITOR OF FERMENTATION OF PALMYRAH SAP?
Ranganathan.Kapilan
Department of Renewable Resources
Picture
                   Figure 1: Palmyrah palm  in Naavatkuli, one of the northern coastal village in SriLanka

Summary

The main source of crude sugar in SriLanka is the sweet sugary sap obtained from the tapped inflorescence of the Palmyrah (Borassus flabellifer) palms. This sap is sterile and highly charged with sugar, but unless special precautions are taken, fermentation by yeast and bacteria leads to accumulation of alcohol and acids.

Lining the inside of the pot with fresh lime, placing the barks of Vateria copallifera and Careya arborea and the leaves of Azadiracta indica  in a clean pot before it is used for collecting sap, are the most common methods used to reduce fermentation.

The objective of the study was to study the effect of various substances used, to prevent fermentation taking place in the palmyrah sap and to recommend the cheapest and easily available, efficient fermentation preventing substance.

Pieces of fresh bark of Vateria copallifera and Careya arborea and leaves of Azadiracta at the same rate (weight -10 g / pot) were put into each collecting pot before use. Another pot was lined with lime. Control was also maintained without any substances. The samples of sap were collected at equal time intervals and analyzed for reducing sugars, alcohol, number of yeast and bacterial cells.

The alcohol content of Palmyrah sap observed in limed pot was very low than that of Vateria copallifera, Careya arborea, Azadiracta and control.  When lime was used, the inhibition of alcohol production is significantly higher than the other substances tested. Vateria and Careya showed a considerable reduction in the amount of sugar when compared to that of control. But lime showed comparatively higher sugar production than all the other treatments. The inhibition of sugar is significantly lower with lime, than the other substances tested except Azadiracta and control. Yeast cells were found in almost all the treatments. Lime, Vateria, Careya and Azadiracta were able to delay the multiplication of yeast cells. But very low amount of yeast cells were found in the limed pot. When Lime was used the number of bacterial cells found in the sap was comparatively very low. Bacterial population was very much reduced by Careya and Azadiracta but the inhibitory action of Vateria was found to be very low. Based on the analysis of the data obtained for sugar, alcohol, bacteria and yeast, lime showed significant difference than all the other treatments tested, except Azadiracta and control in sugar.

Lime is the most effective, cheapest and easily available substance that prevents fermentation of Palmyrah sap. Azadiracta could also be used as an inhibitor next to lime. Due to the poor ability to inhibit fermentation, the barks of Vateria and Careya are not recommended in SriLanka.


Key words – Fermentaion, Palmyrah sap, Lime inhibition.