Judul: Extraction and Enzymatic Hydrolysis of Spirulina sp. Protein as Antioxidant Properties
Abstrak: Spirulina sp. merupakan mikroalga yang dikonsumsi sebagai dietary supplement karena memiliki kandungan gizi utama protein dan aktivitas biologis dalam menginhibisi senyawa radikal bebas. Proses ekstraksi dan hidrolisis protein diduga mampu meningkatkan sifat fungsional serta aktivitas inhibisi radikal bebas 1,1-diphenyl-2-picryl-hydrazyl (DPPH) Spirulina sp.. Tujuan penelitian ini membandingkan pengaruh perbedaan metode ekstraksi terhadap konsentrasi protein, derajat hidrolisis, inhibisi radikal bebas DPPH, serta profil asam amino hidrolisat Spirulina sp.. Spirulina sp. diekstrak dengan metode fisik dan metode kimiawi. Ekstrak yang dihasilkan kemudian dianalisis konsentrasi protein dan dihidrolisis dengan enzim papain, lalu dianalisis derajat hidrolisis dan profil asam amino. Ekstrak dan hidrolisat Spirulina sp. dianalisis inhibisi radikal bebas DPPH pada hari ke-0 dan ke-210 setelah proses hidrolisis. Perbedaan metode ekstraksi berpengaruh signifikan (p < 0,05) terhadap konsentrasi protein ekstrak. Metode fisik menghasilkan ekstrak dengan konsentrasi protein 67,4 ± 14,35 mg/mL, sedangkan metode kimiawi 53,41 ± 3,90 mg/mL. Perbedaan metode ekstraksi berpengaruh signifikan (p < 0,05) terhadap derajat hidrolisis hidrolisat yang dihasilkan. Hidrolisat yang diekstrak dengan metode fisik memiliki derajat hidrolisis 77,14 ± 11,95%, sedangkan metode kimiawi 35,08 ± 15,88%. Hidrolisat dan ekstrak Spirulina sp. mengalami penurunan nilai inhibisi radikal bebas setelah penyimpanan beku. Kandungan asam amino hidrolisat ekstrak metode fisik yaitu 8.711,56 mg/kg, sedangkan metode kimiawi sebesar 3.391,56 mg/kg., Spirulina sp. is a microalgae species that is consumed as a dietary supplement due to its high nutrition content, especially protein and its bioactivity as a radical scavenger. Extraction and hydrolysis processes are expected to enhance Spirulina’s functional characteristic and its bioactivity to inhibit free radicals 1,1-diphenyl-2-picryl-hydrazyl (DPPH). The aim of this study was to compare the effect of two different extraction methods on protein concentration, degree of hydrolysis, DPPH free radical inhibition, and amino acid profile of Spirulina sp. hydrolysate. Spirulina sp. were extracted using two different methods, physical and chemical methods. The crude protein extracts was analyzed using Biuret method and hydrolysed using papain enzyme. The protein hydrolysate was finally run through some analysis such as hydrolysis degree, amino acid profile, and DPPH scavenging activity. The two different extraction methods effected on protein concentration and degree of hydrolysis significantly (p < 0,05). Protein concentration of Spirulina sp. that were extracted using physical method is 67,4 ± 14,35 mg/mL, while Spirulina sp. that were extracted using chemical method is 53,41 ± 3,90 mg/mL. Hydrolysis degree of protein hydrolysate extracted using physical method is 77,141 ± 11,945% while Spirulina sp. that were extracted using chemical method is 35,081 ± 15,884%. Both Spirulina sp. extract and hydrolysate %inhibition decreased after storage. Hydrolysate extracted using physical method contains 8.711,56 mg/kg of amino acid, while hydrolysate extracted using chemical method contains 3.391,56 mg/kg.
Keyword: DPPH radical inhibition, extraction, papain, protein, protein hydrolysate

Judul: Extraction of Bioactive Compounds and Antioxidant Activity of Spirulina platensis
Abstrak: Spirulina platensis merupakan salah satu mikroalga yang memiliki komponen aktif dan berpotensi sebagai antioksidan. Tujuan penelitian ini adalah menentukan komponen aktif, pigmen fikosianin, dan aktivitas antioksidan dari ekstrak S. platensis yang dikultivasi pada media pupuk dan S. platensis komersial. Tahapan penelitian meliputi kultivasi S. platensis pada media pupuk (urea, Gibberellic Acid, dan Plan Catalyst), pemanenan, pengeringan, ekstraksi komponen aktif, dan ekstraksi fikosianin menggunakan metode freeze thawing. Ekstrak S. platensis kultur mengandung flavonoid, fenol, saponin, dan steroid, sedangkan ekstrak S. platensis komersial mengandung saponin dan steroid. Kadar total fenol pada ekstrak S. platensis kultur (15,45±0,85 mg GAE/g) lebih besar dibandingkan ekstrak S. platensis komersial (9,13±0,85 mg GAE/g). Nilai IC50 pada ekstrak S. platensis kultur (277,01±20,6 ppm) menunjukkan aktivitas antioksidan yang lebih tinggi dibandingkan ekstrak S. platensis komersial (522,77±22.23 ppm). Konsentrasi fikosianin pada S. platensis kultur (4,18±0,03 mg/mL) lebih besar dibandingkan S. platensis komersial (1,86±0,02 mg/mL)., Spirulina platensis is one of the microalgae that contains active components and potentially as antioxidant. This study aimed to determine the active components, phycocyanin content, and antioxidant activity of the S. platensis extract cultivated using fertilizer media and commercial S. platensis. The steps of this research were cultivation of S. platensis in fertilizer media (urea, Gibberellic Acid, and Plan Catalyst), harvesting, drying, extraction of active components, and extraction of phycocyanin by freeze thawing method. Spirulina platensis extract from culture contained flavonoids, phenols, saponins, and steroids, while commercial S. platensis extract contained saponins and steroids. The total phenol of cultured S. platensis extract (15.45±0.85 mg GAE/g) was higher compared to that of commercial S. platensis extract (9.13±0.85 mg GAE/g). The IC50 value of cultured S. platensis extract (277.01±20.67 ppm) showed higher antioxidant activity compared to commercial S. platensis extract (522.77±22.23 ppm). The phycocyanin contents of cultured S. platensis (4.18±0,03 mg/mL) was higher compared to commercial S. platensis (1.86±0.02 mg/mL).
Keyword: commercial, culture, phenol, phycocyanin, Spirulina

Judul: Construction of Strongly Optimal Binary Linear Code with Minimum Distance 9 and 11
Abstrak: A binary linear code of length n over q F is a subspace of n q F . A code has three parameters that attached to it, namely length, dimension, and minimum distance. A code with length n, dimension k and minimum distance d is often called [n, k, d ]-code. Usually, when two parameters are given, then we want to find a code that has the best value for the last parameter. Based on Gilbert- Varshamov bound, if a [n, k, d ]-code exists and can not be expanded, we call it a strongly optimal code. In this paper, we construct strongly optimal code with minimum distance 9 and 11. In constructing the code, we created a theorem and algorithm based on Gilbert-Varshamov bound before we implement the algorithm to MAPLE programming language. Because of computational limitations, the program can only construct up to k = 10 for d = 9 and k = 12 for d = 11.
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