Judul: Aktivitas protease dan kandungan asam laktat pada yoghurt yang dimodifikasi Bifidobacterium bifidum dan diinokulasi pseudomonas fluorescens
Abstrak: Main health benefical related to yoghurt is its ability to improve lactose digestion and to control the pathogenic bacteria in digestion tract. This benefical health is threatened by natural existence of contaminant in milk especially P. fluorescens, that reduces shelf life of milk. The aim of this research is to determine the antagonistic nature of B. bifidum in inhibiting growth P. fluorescens and the effect of B. bifidum on protease activity and lactic acid content of yoghurt inoculated by P. fluorescens. Antagonism test of B. bifidum to P. fluorescens is conducted using turbidimetric method. Total titratable acid was measured to determine the percentage of lactic acid content by using acid base titration principle. Protease activity was measured with modification of Lowry method. The result of antagonism test showed that B. bifidum can inhibit P. fluorescens with minimum inhibitory concentration (MIC) of 2%. Lactic acid content of yoghurt with formula 1:1:0, 1:1:0.5, 1:1:1, and 1:1:1.5 on 0 day was 0.3747%, 0.3654%, 0.3732%, and 0.347% respectively and then increased during 25 day storage to 0.5709%, 0.5202%, 0.6638%, and 0.5945% respectively. Addition of B. bifidum decreased protease activity indicated by less protease activity of yoghurt modified by B. bifidum till 15 day storage compared to yoghurt without B. bifidum.
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Judul: Aktivitas Antibakteri dan Antioksidan Peptida Bioaktif Yoghurt yang Difermentasi dengan Lactococcus lactis Rekombinan
Abstrak: Yoghurt merupakan pangan fungsional yang dipercaya punya efek terhadap kesehatan. Efek tersebut salah satunya dikaitkan dengan keberadaan peptida bioaktif hasil fermentasi susu oleh bakteri asam laktat. Lactococcus lactis rekombinan merupakan bakteri asam laktat yang dapat menghasilkan plantarisin. Plantarisin diketahui memiliki efek antimikroba dan telah diuji sebagai bahan pengawet pada beberapa jenis pangan. Penelitian ini bertujuan menguji aktivitas antioksidan dan antibakteri yoghurt yang telah ditambahkan bakteri rekombinan L. lactis sebagai kultur starter. Selain itu juga untuk mengukur perubahan aktivitasnya setelah penyimpanan. Water soluble peptide extract (WSPE) yoghurt didapatkan dari hasil sentrifugasi dingin dan pemekatan dengan freeze dry. Kadar protein WSPE diukur terlebih dahulu dengan BCA kit sebelum dilakukan uji lanjutan. Yoghurt D hasil penyimpanan dengan total protein 5.226 mg/mL memiliki aktivitas antibakteri paling baik dengan zona bening 6.5 mm dan aktivitas antioksidan 20.11%. Hasil konfirmasi protein dengan trisin SDS-PAGE menunjukkan telah terjadi hidrolisis protein α-S2kasein (25.76 kD) pada sampel WSPE yoghurt D segar maupun penyimpanan.
Keyword: Antibakteri, Antioksidan, Peptida Bioaktif, WSPE

Judul: Real Option Valuation Using Binomial Decision Trees.
Abstrak: A firm that decides to invest has a choice to invest in real assets. A method which is usually used in valuation of the project is discounted cash flow (DCF) method. But, this method can’t be used in projects that account for value of managerial flexibility, such as decision to suspend operations temporarily. Therefore, this kind of project needs to be assessed using real option. Real option valuation can be done in some ways, including the use of path-dependent simulation, as well as closed-form models like Black-Scholes model, partial differential equation, and binomial or multinomial approaches. In this paper, real option valuation using binomial decisions id discussed. Determination of the project value can be done in three steps. First, calculate the expected present value of the project. Next, calculate volatility of the project using Monte Carlo simulation. Last, construct a binomial tree to model the dynamics of the project value using the parameters of the stochastic process, and then add some decision nodes to model the project’s real options.
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