Judul: Fermentation of Spirulina plantensis by Lactobacillus plantarum SK(5) and its Fortification on Probiotic Ice Cream
Abstrak: Spirulina dapat berperan sebagai prebiotik bagi bakteri bakteri asam laktat probiotik. Lactobacillus plantarum SK(5) merupakan bakteri asam laktat asal bekasam yang bersifat sebagai probiotik. Penelitian ini bertujuan menentukan karakteristik spirulina fermentasi dan pengaruh perbedaan konsentrasi spirulina fermentasi terhadap karakteristik es krim spirulina probiotik. Spirulina platensis diperoleh melalui kultivasi mandiri selama 13 hari dengan nilai optical density (OD) sebesar 0,54. Biomassa spirulina difermentasi menggunakan Lactobacillus plantarum SK(5) pada suhu 37℃ selama 48 jam. Karakteristik spirulina fermentasi yang dihasilkan yaitu pH 3,38, total asam tertitrasi 0,7% dan total bakteri asam laktat 8,15 log cfu/mL. Spirulina fermentasi selanjutnya difortifikasi ke dalam es krim dengan formula E0 (tanpa penambahan spirulina fermentasi), E10 (10 g), E15 (15 g), dan E20 (20 g). Data yang dianalisis pada es krim probiotik meliputi overrun, total padatan, daya leleh, komposisi kimia (protein, lemak, air, abu, dan karbohidrat), total BAL, kadar TAT dan nilai pH. Es krim spirulina probiotik memiliki overrun 19,25-20,42%, total padatan 40,55-42,37%, daya leleh 1,41- 1,53%, kadar protein 6,23-7,33%, kadar lemak 3,49-3,37%, kadar air 57,63- 59,46%, kadar abu 1,70-1,85%, karbohidrat 28,67-29,72%, nilai pH 6,22-6,27, total asam tertitrasi 0,52-0,68%, dan total bakteri asam laktat 0,00-6,59 log cfu/mL. Es krim yang difortifikasi dengan spirulina fermentasi dapat dinyatakan sebagai produk probiotik. Perlakuan terbaik yaitu formula es krim E20 (fortifikasi spirulina sebanyak 20 g), mempunyai karakteristik total padatan 41,79%, kadar protein 7,33%, total BAL 6,59 log cfu/mL (106 cfu/mL) kadar TAT 0,86% dan nilai pH 6,22., Spirulina can act as a prebiotic for probiotic lactic acid bacteria. Lactobacillus plantarum SK(5) is a lactic acid bacteria from fermented fish product which acts as a probiotic. This study aims to determine the characteristics of fermented spirulina and the effect of different concentrations of fermented spirulina on the characteristics of probiotic spirulina ice cream. Spirulina platensis was obtained through self-cultivation for 13 days with an optical density (OD) value of 0,54. Spirulina biomass was fermented using Lactobacillus plantarum SK(5) at 37℃ for 48 hours. The characteristics of fermented spirulina produced were pH 3,38, total titrated acid 0,7% and total lactic acid bacteria 8,15 log cfu/mL. The fermented spirulina was then fortified into ice cream with the formula E0 (without the addition of fermented spirulina), E10 (10 g), E15 (15 g), and E20 (20 g). Characterization of probiotic ice cream included overrun, total solids, melting power, chemical composition (protein, fat, water, ash, and carbohydrates), total LAB, TAT content and pH values. Characteristics of probiotic spirulina ice cream were overrun of 19,25-20.42%, total solids 40,55-42,37%, melting power 1,41- 1,53%, protein content 6,23-7,33%, fat content 3,49-3,37%, water content 57,63- 59,46%, ash content 1,70-1,85%, carbohydrates 28,67-29,72%, pH value 6,22-6,27, total titrated acid was 0,52-0,68%, and total lactic acid bacteria was 0,00-6,59 log cfu/mL. Ice cream fortified with fermented spirulina can be declared as a probiotic product. The best treatment was ice cream formula E20 (it fortified with fermented spirulina of 20 g), which had the characteristics of total solids 41,79%, protein content 7,33%, total LAB 6.59 log fcu/mL (106 cfu/mL), TAT content 0,86% and pH value 6,22.
Keyword: Spirulina, Es krim, Fermentasi, Lactobacillus plantarum SK(5), Bakteri asam laktat, Ice cream, Probiotik, Probiotic, Lactic acid bacteria, Fermentation, Fermented spirulina, Spirulina fermentasi

Judul: Characteristics of Spirulina Yoghurt by starter Lactobacillus plantarum SK(5) in Different Biomass Concentration and Incubate Term
Abstrak: Lactobacillus plantarum SK(5) merupakan bakteri probiotik asal bekasam dan dapat digunakan sebagai starter dalam pembuatan yoghurt. Spirulina platensis termasuk kedalam cyanobacteria yang memiliki banyak manfaat bagi tubuh. Penambahan spirulina dalam fermentasi yoghurt dengan starter L. plantarum SK(5) bertujuan menentukan suhu dan lama fermentasi yoghurt spirulina berdasarkan perubahan pH menentukan pengaruh perbedaan konsentrasi spirulina basah dan waktu inkubasi terhadap nilai pH, kadar asam tertitrasi, dan total BAL yoghurt spirulina; serta menentukan karakteristik yoghurt terpilih setelah fermentasi 24 jam. Penelitian terdiri dari empat tahap yaitu 1) penyegaran dan kultivasi spirulina; 2) penyiapan kultur starter L. plantarum SK(5); 3) penentuan waktu dan suhu inkubasi yoghurt spirulina; 4) Pembuatan yoghurt spirulina dengan waktu dan suhu inkubasi terpilih menggunakan starter L. plantarum SK(5). Suhu dan lama fermentasi terbaik pada yoghurt spirulina terpilih yaitu 37oC dan 24 jam. Penambahan spirulina dan waktu inkubasi mempengaruhi secara nyata terhadap nilai pH, kadar TAT, dan total BAL yoghurt spirulina. Penambahan spirulina 1.5% dengan lama fermentasi 24 jam merupakan perlakuan terpilih berdasarkan nilai pH dan kadar TAT. Karakteristik dari yoghurt spirulina terpilih memiliki nilai pH 3.9, kadar TAT 1.195%, Total BAL 9.11 log cfu/mL, viskositas 85.25 cPs, kadar protein 38.43%, kadar lemak 26.93%, dan nilai IC50 297.06 mg/L., Lactobacillus plantarum SK(5) is a probiotic bacteria which isolated from bekasam and that can be used as starter in yoghurt process. Spirulina platensis belong to cyanobacteria which hold many function for healthy. The addition spirulina in yoghurt with starter L. plantarum SK(5) expected to determined effect of temperature and time of fermentation yoghurt spirulina by based on pH, determined effect of spirulina wet biomass concentration and incubation time to pH, total acid content, with total L. plantarum SK(5), and the characteristics of selected product after fermentation for 24 hours. This research consist to four stage namely 1) refreshing and cultivation of spirulina; 2) the preparation culture starter L. plantaurm SK(5); 3) the determination time and temperature of incubation yoghurt spirulina; 4) the production yoghurt spirulina with the selected time and temperature using L. plantarum SK(5) as starter. The temperature and incubation time selected for spirulina yoghurt were 37oC and 24 hour. The addition spirulina and incubation time had a significant effect on the pH alue, the levels of TAT, and total LAB yoghurt spirulina.The best treatments in this research was the addition of 1.5% spirulina with incubation times of 24 hours. Characteristics of yoghurt spirulina 1.5% include pH 3.9, total acids contents 1.195%, total LAB 9.11 log cfu/mL, viscosity 85.25 cPs, protein contents 3.00%, fat contents 3.14%, and IC50 287.06 mg/L
Keyword: lactic acids, Lactobacillus plantarum SK(5), probiotic, spirulina, spirulina yoghurt

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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