Judul: Karakteristik Sensori dan Kimia Snack Bar Buah Kering dengan Penambahan Spirulina platensis
Abstrak: Komponen bioaktif pada Spirulina platensis dapat meningkatkan gizi pada snack bar yang umumnya hanya terbuat dari campuran serealia, kacang, dan buah-buahan. Penambahan buah kering misalnya buah naga, nanas, dan kismis dapat meningkatkan kandungan gizi, menambah cita rasa, serta menutupi rasa dan bau amis akibat penambahan S. platensis pada snack bar. Penelitian ini bertujuan menentukan karakteristik snack bar buah kering spirulina berdasarkan sensori serta kimia pada formula terpilih. Formulasi snack bar buah kering spirulina dilakukan dengan perlakuan penambahan S. platensis yang berbeda (0%, 1%, 2%, dan 3%). Formula snack bar buah kering spirulina terpilih berdasarkan uji hedonik yaitu penambahan S. platensis 1% yang memiliki kadar air sebesar 9,19%, kadar abu 1,46%, protein 6,51%, lemak total 6,60%, karbohidrat 76,24% (by difference), serat pangan 7,52%, serta nilai kalori sebesar 390,43 kkal/100 g. Kandungan senyawa bioaktif yang terdapat pada formula terpilih antara lain senyawa alkaloid, flavonoid, dan fenol yang berpotensi sebagai senyawa antioksidan dengan nilai IC50 sebesar 866,61 ppm., The bioactive components in Spirulina platensis can enhance the nutritional value of snack bars, which are typically made from a mixture of cereals, nuts, and fruits. The addition of dried fruits such as dragon fruit, pineapple, and raisins will increase the nutritional content, add flavor, and cover the fishy taste and odor resulting from the addition of S. platensis to the snack bars. This study aims to determine the sensory and chemical characteristics of dried fruit spirulina snack bars based on the selected formula. The formulation of dried fruit spirulina snack bars was conducted with different treatments of S. platensis addition (0%, 1%, 2%, and 3%). The selected formula of the snack bars based on hedonic testing is the one with 1% addition of S. platensis, which has a moisture content of 9.19%, ash content of 1.46%, protein content of 6.51%, total fat content of 6.60%, carbohydrate content of 76.24% (by difference), dietary fiber content of 7.52%, and calorie content of 390.43 kcal/100 g. The selected formula contained bioactive compounds, including alkaloids, flavonoids, and phenols, which have the potential as antioxidant compounds with an IC50 value of 866.61 ppm.
Keyword: Antioxidant, dried fruits, proximate, snack bars, Spirulina platensis

Judul: Physical and Chemical Characteristic of Sweet Potato (Ipomea batatas L.) Jam Slices With Addition of Spirulina platensis
Abstrak: Komponen kimiawi pada Spirulina platensis dapat meningkatkan nutrisi produk selai lembaran dengan bahan baku ubi jalar dan penambahan S. platensis. Spirulina merupakan mikroalga yang mengandung nutrisi lengkap diantaranya protein, lemak, karbohidrat , asam nikotinat, riboflavin, thianin, mineral, fikosianin, dan karotenoid. Penelitian ini bertujuan mengevaluasi penerimaan sensori, fisikokimia, serta kandungan antioksidan pada selai lembaran berbahan baku ubi jalar dengan penambahan S. platensis pada konsentrasi berbeda. Konsentrasi S. platensis yang digunakan dalam penelitian ini adalah 1%; 1,5%; dan 3%. Penambahan S. platensis berpengaruh terhadap kesukaan panelis. Senyawa yang terdeteksi pada selai lembaran ubi jalar dengan penambahan S. platensis yaitu alkaloid, saponin, steroid, dan fenol., The chemical components in S. platensis can enhance the nutritional value of sweet potato jam slices with the addition of S. platensis. Spirulina is a microalgae that contains complete nutrients including protein, fat, carbohydrates, nicotinic acid, riboflavin, thiamine, minerals, phycocyanin, and carotenoids. This study aims to evaluate sensory acceptance, physicochemical properties, and antioxidant content in sweet potato jam slices with the addition of S. platensis at different concentrations. The concentrations of S. platensis used in this study were 1%, 1.5%, and 3%. The addition of S. platensis has an effect on panelists' preference. Compounds detected in sweet potato jam slices with the addition of S. platensis were alkaloids, saponins, steroids, and phenols.
Keyword: antioxidant, jam slices, phytochemical profile, Spirulina platensis

Judul: Bifurkasi Hopf pada Model Siklus Bisnis Kaldor Kalecki tanpa dan dengan Waktu Tunda
Abstrak: Business cycle model is one of dynamical system models in economic. One of the business cycles model is Kaldor-Kalecki model. Kaldor-Kalecki business cycle model that is written in delayed defferential equations, is a business cycle model that involves gross product and capital stock of a company. In this paper Kaldor-Kalecki business cycle model is analyzed using both nondelay and delay in time of capital stock. By Taylor expansion for the time delayed model, an analysis of stability around the fixed points has been done. Furthermore, by using Hopf bifurcation theorem, it can be shown that there exists periodic orbits and limit cycle. In the nondelayed model, changing the parameter of goods market could lead to the occurrence of Hopf bifurcation and the existence of limit cycle. Similarly, for the delayed model, it has been shown that changing the time delay parameter may result in the occurrence of Hopf bifurcation and limit cycle.
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