Judul: . Total Phenolic, Flavonoid, and Antioxidant of Scoby Kombucha Tea Camellia sinensis (L.) Kuntze with Variation of Sucrose Concentration
Abstrak: Mother of SCOBY sebagai inokulum utama dalam pembuatan kombucha, berfungsi memastikan pertumbuhan bakteri dan ragi yang sesuai. Penelitian ini menganalisis dan mengukur kadar total fenolik, kadar total flavonoid, dan aktivitas antioksidan mother of SCOBY metode FRP (Ferric Reduction Power), DPPH, dan AEAC (Ascorbic acid Equivalent Antioxidant Capacity) dengan konsentrasi sukrosa berbeda. Mother of SCOBY dibuat dalam enam formula kombucha dengan konsentrasi sukrosa 0% (F1), 5% (F2), 7.5% (F3), 10% (F4), 12.5% (F5), dan 15% (F6). Hasil menunjukkan kadar fenolik tertinggi ditemukan pada F5 dan terendah pada F6, kadar flavonoid tertinggi pada F4 dan terendah pada F6. Aktivitas antioksidan paling kuat pada F5 dan paling lemah pada F6, seperti yang ditunjukkan oleh nilai inhibisi dan IC50. Uji FRP menunjukkan nilai tertinggi pada F4 dan terendah pada F6. Kata kunci: antioksidan, kombucha, mother of SCOBY, sukrosa, Mother of SCOBY as the main inoculum in making kombucha, serves to ensure the growth of appropriate bacteria and yeast. This study analyzed and measured total phenolic content, total flavonoid content, and antioxidant activity of mother of SCOBY using FRP (Ferric Reduction Power), DPPH, and AEAC (Ascorbic acid Equivalent Antioxidant Capacity) methods with different sucrose concentrations. Mother of SCOBY was made into six kombucha formulas with sucrose concentrations of 0% (F1), 5% (F2), 7.5% (F3), 10% (F4), 12.5% (F5), and 15% (F6). Results showed the highest phenolic content was found in F5 and the lowest in F6, the highest flavonoid content in F4 and the lowest in F6. Antioxidant activity was strongest in F5 and weakest in F6, as indicated by the inhibition and IC50 values. FRP assay showed the highest value in F4 and the lowest in F6. Keywords: antioxidant, kombucha, mother of SCOBY, sucrose
Keyword: Kombucha, Fenolik, flavonoid, Antioksidan, scoby

Judul: Aktivitas Antioksidan Kombucha Camellia sinensis (L.) Kuntze dengan Variasi Konsentrasi Sukrosa.
Abstrak: Kombucha merupakan minuman fungsional hasil fermentasi teh dengan kandungan antioksidan yang memiliki kemampuan dalam menghambat radikal bebas pemicu penyakit degeneratif. Penelitian ini bertujuan menentukan konsentrasi sukrosa terbaik untuk menghasilkan minuman kombucha dengan kandungan fenolik, flavonoid dan aktivitas antioksidan optimum. Kombucha pada penelitian ini dibuat menjadi 5 formula dengan konsentrasi sukrosa 0%;5%;7,5%;10%;12,5% dan 15% dengan waktu fermentasi 8 hari. Baby SCOBY hasil fermentasi kombucha memiliki kandungan air sebesar 81-95%. Kombucha F4 dengan konsentrasi sukrosa 10% memiliki kandungan total fenolik dan flavonoid paling optimum mencapai 1152,12 ± 7,93 mg GAE/100 mL dan 554,09 ± 8,70 mg QE/100 mL kombucha. Aktivitas antioksidan kombucha yang diuji melalui metode DPPH, AEAC dan Ferric Reducing Power (FRP) menunjukkan kombucha dengan konsentrasi sukrosa 10% juga memiliki aktivitas antioksidan optimum dengan nilai IC50 sebesar 22,01 ± 0,31 µL/mL, kapasitas antioksidan setara dengan 440,57 ± 4,63 mg asam askorbat, serta potensi daya reduksinya yang paling kuat diantara formula lainnya sebesar 2466,43 ± 36,89 mg AAE/100 mL. Hasil analisis menunjukkan adanya pengaruh konsentrasi sukrosa terhadap kadar air baby SCOBY, kandungan total fenolik, flavonoid dan aktivitas antioksidan kombucha (p<0,05)., Kombucha is a functional beverage resulting from fermented tea containing antioxidants which have the ability to inhibit free radicals that trigger degenerative diseases. This research aimed to determine the best sucrose concentration to produce kombucha drinks with optimum phenolic, flavonoid and antioxidant activity content. Kombucha in this study was made into 5 formulas with sucrose concentrations of 0%; 5%; 7,5%; 10%; 12,5% and 15% with a fermentation time of 8 days. Baby SCOBY fermented kombucha has a water content of 81-95%. Kombucha F4 with a sucrose concentration of 10% had the optimum total phenolic and flavonoid content reaching 1152,12 ± 7,93 mg GAE/100 mL and 554,09 ± 8,70 mg QE/100 mL kombucha. The antioxidant activity of kombucha tested using teh DPPH, AEAC and Ferric Reducing Power (FRP) methods showed that kombucha with a sucrose concentration of 10% also had optimum antioxidant activity with an IC50 value of 22,01 ± 0,31 µL/mL with an antioxidant capacity equivalent to 440,57 ± 4,63 mg of ascorbic acid, and the potential for the strongest reduction power among other formulas, amounting to 2466,43 ± 36,89 mg AA/100 mL). The results of the analysis showed that there was an influence of sucrose concentration on the water content of baby SCOBY, total phenolic content, flavonoids and antioxidant activity of kombucha (p<0,05).
Keyword: Antioxidant, green tea, kombucha, sucrose concentration

Judul: The Solution of Nonlinear Volterra Integral Equation using Linearization Method.
Abstrak: Many natural phenomena can be explained by mathematical models. One of those models is in the form of Volterra integral equation, which is usually nonlinear. Analitically, a nonlinear form is difficult to solve. Therefore, this research is aimed to discuss solution of Volterra integral equation using linearization method. Linearization is done to nonlinear integrand with Taylor series expansion. According to this linearization, a numerical solution of Volterra integral equation is obtained using MATLAB 7.0.1 software. Validity of this method is tested by comparing the approximate with the exact solution. The result of this research shows that the numerical solution agree with the exact solution quite well.
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