Judul: Characteristic of Powdered Spirulina Yoghurt with Lactobacillus plantarum SK (5) Starter During Storage
Abstrak: Pembuatan yoghurt spirulina bubuk dengan metode spray drying dapat dilakukan untuk meningkatkan masa simpan produk yoghurt spirulina. Tujuan penelitian ini membandingkan karakteristik yoghurt spirulina cair dan bubuk dan menentukan pengaruh penyimpanan terhadap nilai aw, viabilitas bakteri asam laktat, dan aktivitas antioksidan yoghurt spirulina bubuk selama 28 hari di suhu ruang. Yoghurt spirulina dibuat melalui fermentasi susu dengan 15% starter L. plantarum SK (5) dan 1.5% biomassa basah S. platensis hasil kultivasi. Yoghurt spirulina bubuk disimpan dalam kemasan PET/ALU/LLDPE pada suhu ruang (27-29 oC), lalu dilakukan pengamatan setiap 7 hari. Yoghurt spirulina bubuk memiliki kadar air, kadar protein, kadar lemak, nilai pH, kadar TAT, total BAL, dan aktivitas antioksidan yang berbeda nyata dengan yoghurt spirulina cair. Yoghurt spirulina bubuk memiliki rendemen 6.42%, nilai aw 0.32, kelarutan 72.75%, dan ukuran partikel 5.818 µm. Perlakuan lama penyimpanan tidak berpengaruh secara nyata terhadap total BAL yoghurt spirulina bubuk (P<0,05), namun nilai aw dan aktivitas antioksidan yoghurt spirulina bubuk mengalami perubahan yang signifikan setelah penyimpanan 28 hari., Spirulina yoghurt shelf life could be improved by making a powdered yoghurt with spray drying method. The aim of this study was to compare the characteristics of liquid and powdered spirulina yoghurt and the changes in water activity (aw), lactic acid bacteria (LAB) viability, and antioxidant activity of powdered spirulina yoghurt during 28 days of storage. Spirulina yoghurt was made by fermentation process of milk with 15% starter of L. plantarum SK (5) dan 1.5% wet biomass of cultivated S. platensis. Spirulina yoghurt powder was kept in PET/ALU/LLDPE pouches at room temperature (27-29 oC), and observed per 7 days. The moisture content, protein content, fat content, pH values, TAT levels, total LAB, and antioxidant activity of spirulina yoghurt powder has a significant difference with spirulina liquid yoghurt. Spirulina yoghurt powder has 6.42% of yield, 0.32 of aw level, 72.75% of solubility, and 5.818 µm of particle size. The storage time treatment did not affect the total LAB of spirulina yoghurt powder significantly (P<0,05), but the aw levels and antioxidant activity was changed significantly after 28 days storage.
Keyword: antioksidan, fermentasi, Lactobacillus plantarum SK (5), probiotik, spray drying, yoghurt

Judul: Lactobacillus plantarum SK(5) Asal Bekasam sebagai Starter dalam Fermentasi Yoghurt Spirulina
Abstrak: Lactobacillus plantarum SK(5) asal bekasam dapat dimanfaatkan sebagai kultur starter dalam pembuatan yoghurt. Bubuk spirulina dapat digunakan sebagai prebiotik yang mampu meningkatkan pertumbuhan dan daya tahan probiotik. Tujuan penelitian ini menentukan pengaruh penambahan spirulina terhadap karakteristik yoghurt yang difermentasi menggunakan starter L. plantarum SK(5) asal bekasam. Perlakuan yang digunakan pada penelitian ini yaitu penambahan spirulina 0%, 0.25%, 0.5%, dan 0.75% (b/v campuran). Penambahan spirulina mempengaruhi secara nyata kadar total asam tertitrasi (TAT), pH, kadar protein, dan viskositas yoghurt. Penambahan spirulina tidak mempengaruhi secara nyata total BAL, kadar lemak, dan total padatan yoghurt. Perlakuan terpilih yaitu perlakuan spirulina 0.5% berdasarkan kadar protein dan karakteristik lainnya yang telah memenuhi standar yoghurt. Perbedaan lama fermentasi mempengaruhi secara nyata total BAL, kadar TAT, dan pH yoghurt perlakuan spirulina terpilih.
Keyword: Lactobacillus plantarum SK(5), probiotic, spirulina, yoghurt

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.
Keyword: