KAJIAN EKSTRAKSI RUMPUT LAUT COKLAT (Sargassum cristaefolium)MENJADI ALGINAT BERDASARKAN KONSENTRASI Na2CO3DAN LAMA PEMANASAN SERTA PENGGUNAANNYA PADA SIRUP SARI MAWAR

Alginate is a hydrocolloid extracted from brown seaweed (S. cristaefolium) which contains high fiber and is easily soluble in water. Alginate can be used as a thickener in rose syrup. This study aims to produce alginate from extraction of S. cristaefolium with different concentrations of Na2CO3 and the heating time and application of alginate as thickener in rose syrup. This study consisted of two phase, the first phase was the extraction process of brown seaweed S. cristaefolium into alginate using a factorial randomized block design with factor 1 was the concentration of Na2CO3 with levels (5%; 6%; 7%) and factor 2 was heating time with levels (1,5 hours; 2 hours; 2,5 hours). Parameter observed included water content, ash content, viscosity, yield, pH value, and brightness level. While the second phase of th research was the use of alginate in rose syrup using a completely randomized design with the best treatment factor of S. cristaefolium brown seaweed alginate from the result of phase 1 research with levels (0%; 0,5%; 1%). The observed parameters included pH value, antioxidant activity, total anthocyanin, vitamin C, total dissolved solids, total sugar, viscosity, and organoleptics. Based on the result of the first phase of the study it was found that the concentration of Na2CO3 and the heating time interacted signigficantly in water content, yield, and viscosity. The best treatment for brown seaweed alginate S. cristaefolium is N3T3 ( 7% Na2CO3; 2, 5 hours heating time), namely water content of 13,53%; ash content 23,84%; 8,28% yield; pH value 7,2; viscosity 8,33 d.Pas; and brightness of 62,47. The best treatment in the second phase of the study was S1 rose syrup (addition of 0,5% alginate). The value of the analysis of physic-chemical parameters of rose syrup treatment S1 (addition of 0,5% alginate) is the total anthocyanin 6,62 mg/mL; antioxidant activity 80,09%; total sugar 66,09%, vitamin C 0,76 mg/ 100 g; total dissolved solids 31,30 oBrix; pH value 4.53; and viscosity of 5,17 d.Pas