STABILITAS MIKROEMULSI FUCOXANTHIN DAN EFEKTIFITASNYA DALAM MENGHAMBAT FOTO OKSIDASI VITAMIN C PADA MODEL MINUMAN (Fucoxanthin Microemulsion Stability and Its Effectiveness in Inhibiting Photooxidation of Vitamin C in Beverage Model)

Fucoxanthin microemulsion was prepared by dissolvingfocoxanthin in Virgin Coconut Oil (VCO) and mixture of surfactants (Tween 20:Tween 80:Span 80 = 92:5.5:2.5 (% v/v)with oil-surfactan ratio 15:85 v/v, then added with water until the concentration reaching 600 ppm fucoxanthin. The fucoxanthin microemulsions were analyzed the stability towards pH, the samples were diluted 50 times and 100 times with water media and citrate buffer (pH:3.5; 4.5 and distilled water pH 6.5). Subsequently, the samples were tested for centrifugation and storage stability at room temperature. The appearance of fucoxanthin microemulsion stability was measured with spectrometer UV/VIS at a wavelength of 458 nm. The beverage models were made of vitamin C (450 mg/L), citric acid (1%) and sucrose (6%). Fucoxanthin microemulsions were added to the beverage model that had been diluted 50 time and 100 time with distilled water pH 6.5. Subsequenly, the samples were added 5 ppm erytrhosine as a sensitizer and without erytrhosine as control. The beverage models were exposed to flourescent light with an intensity of 2000 lux. Vitamin C concentration was mesured by the method of riboflavin-sensitized photodynamic UV spectrophotometry every 2 hours. Fucoxanthin microemulsions were stable at pH 3.5 to 6.5 and even the heating treatment, centrifugation and dilution. Fucoxanthin microemulsion above 6 ppm was not effective in inhibiting degradation rate of vitamin C on photooxidation in beverage models. Keywords: Microemulsions, fucoxanthin, photooxidation, ascorbic acid ABSTRAK Mikroemulsi fucoxanthin dibuat dengan melarutkanfucoxanthin dalam VCO dan ditambah surfaktan (Tween 20:Tween 80:Span 80 = 92:5,5: 2,5 (% v/v), dengan rasio minyak-surfaktan 15:85 v/v, kemudian ditambahkan air hingga konsentrasi fucoxanthin mencapai 600 ppm. Mikroemulsi fucoxanthin dianalisis stabilitasnya meliputi pengujian stabilitas terhadap pH yang dilakukan pengenceran 50 kali dan 100 kali dengan media air dan buffer sitrat (pH: 3,5; 4,5 dan aquades pH 6,5). Selanjutnya sampel-sampel tersebut diuji stabilitasnya terhadap sentrifugasi dan penyimpanan pada suhu kamar. Stabilitas kenampakan mikroemulsi fucoxanthin diukur absorbansinya dengan spektrometer UV/VIS pada panjang gelombang 458 nm. Model minuman merupakan larutan yang tersusun dari vitamin C (450 mg/L), asam sitrat (1%) dan sukrosa (6%). Mikroemulsi fucoxanthin yang ditambahkan ke dalam model minuman yang telah diencerkan 50 kali dan 100 kali dengan aquades pH