The Influence of Heating Time of Coconut Milk on The Influence of Heating Time of Coconut Milk on Free Fatty Acids Formation Free Fatty Acids Formation

Abstract

The  most  important  part  of  coconut  fruit  is  coconut  meat  that  contains  some chemical substances such as protein, carbohydrates, and oil. These substances present also in food preparing from coconut meat, including coconut milk.  Some traditional of Indonesian‘s  foods  prepared  from  coconut  milk  will  soon  spoilage  due  to  chemical changes of the substances. Oil hydrolysis liberates free fatty acids and glycerol. Free fatty acids of short chain are odorous.  Hydrolysis is catalyzed by lipase. The optimum temperature of this enzyme activity is 30–40 ^oC, the range of room temperature, therefore the coconut milk contained food will be odorous or off flavor in a relative short time. Time has a role in determining the amount of hydrolyzed product. The longer time the greater result, unless there is an inhibitor. The purpose of this research is to know the influence of heating time of coconut milk  on  free  fatty  acids  formation.  The  experimental  design  used  is  completely randomized. The coconut milk was heated at 37OC for 2; 4; 6; 8; 10; 12; and 14 hours. The experiment without heating also carried out at the same time. The top layer formed was transferred and it was then heated until the oil obtained. The oil was analyzed for of free fatty acids content, and it was then isolated, and esterified with methanol. The methyl ester was analyzed by GC equipped with capillary column.  The biggest amount of free fatty acids  was after 14 hour by heating of 0.375%,  whereas  without heating was 0.325%. The odor was detected after 10 hours heating, and 12  without heating, containing free fatty acid of 0.300% and 0.315%, respectively.

Key words: coconut milk, lipase, oil, and free fatty acids