Effect of glucomannan and sugar concentration for physicochemical and organoleptic characteristics of dragon fruit skin slice jam

The high consumption of dragon fruit causes a high amount of dragon fruit skin waste produced that still has benefits and nutritional value. Amorphophallus oncophyllus contain high glucomannan. Glucomannan as a hydrocolloid has gelling agent properties. Water in food can also be reduced in the presence of sugar which has hygroscopic properties. The purpose of this research is to describe effect of glucomannan and sugar concentration for physicochemical and organoleptic dragon fruit skin slice jam. The treatments are glucomannan (1%, 1.5%, 2%), sugar (10%, 15%, 20%), and single control (glucomannan 1% with sugar 0%). Samples were analyzed by color, water activity, syneresis, total solid soluble (TSS), texture, and hedonic test. The result showed that the addition of glucomannan and sugar significantly affect decrease of water activity, syneresis and increase TSS and texture. Based on overall hedonic test, panelist preferred 1% glucomannan with 15% sugar formulation.