Judul: Formulation of High-Fiber Extruded Purple Sweet Potato (Ipomoea batatas L.) and Red Kidney Bean (Phaseolus vulgaris)
Abstrak: Rendahnya asupan serat pangan yang berkaitan erat dengan peningkatan risiko beragam penyakit tidak menular (PTM) masih menjadi masalah kesehatan terkait gizi pada masyarakat luas. Ubi ungu dan kacang merah merupakan pangan tinggi serat yang terjangkau dan mudah diakses di Indonesia. Penelitian ini bertujuan mengembangkan formulasi olahan ubi ungu dan kacang merah berupa ekstrudat tinggi serat. Tahapan penelitian terdiri dari optimasi formula, evaluasi sensori, uji karakteristik fisik yakni analisis warna dan tekstur, analisis proksimat, analisis serat pangan, baik larut dan tidak larut, dan analisis aktivitas air. Optimasi formula dilakukan menggunakan empat formulasi dengan perbandingan penggunaan tepung ubi ungu dan tepung kacang merah yang berbeda-beda yakni F0 (100:0), F1 (80:20), F2 (70:30), dan F3 (60:40). Ekstrudat diekstrusi pada suhu 60°C dan kecepatan ulir, umpan, serta pisau sebesar berturut-turut 45, 45, dan 50 Hz. Formula terpilih yakni formula F2 ditentukan berdasarkan hasil seluruh analisis. Satu takaran saji ekstrudat formula F2 diketahui mengandung mengandung energi, protein, lemak, karbohidrat, dan total serat pangan berturut-turut sebesar 129 kkal, 4,0 g, 0,3 g, 27,7 g, dan 6,0 g, serta memenuhi 6,0% kebutuhan energi serta 19,9% kebutuhan serat orang dewasa. Analisis aktivitas air menunjukkan bahwa formula terpilih memiliki aktivitas air sebesar 0,44%. Formula ekstrudat terpilih berpotensi memenuhi klaim sebagai pangan tinggi serat dan rendah lemak dengan umur simpan yang cukup panjang., The low intake of dietary fiber, which is closely related to the increased risks of various non-communicable diseases (NCDs), is still considered as a major health problem related to nutrition globally. Purple sweet potatoes and red kidney bean are high-fiber foods that are affordable and readily accessible in Indonesia. This research aimed to develop a formulation of high-fiber extrudate made from purple sweet potato and red kidney bean. This research was conducted through formula optimization, sensory evaluation, and analyses of color, texture, proximate, dietary fiber, and water activity. Optimization of the formula was carried out using four formulations with different ratios of purple sweet potato and red kidney bean flours, i.e. F0 (100:0), F1 (80:20), F2 (70:30), and F3 (60:40). The extrudate was extruded using a double-screw extruder at the temperature of 60°C, with the screw, feed and cutter speeds of 45, 45, and 50 Hz, respectively. The selected extrudate formula, formula F2, was determined based on the results of all analyses. A single serving of F2 extrudate was shown to contain energy, protein, fat, carbohydrates and total dietary fiber of 129 kcal, 4.0 g, 0.3 g, 27.7 g, and 6.0 g respectively, and contributes to 6.0% and 19.9% of energy and fiber needs for adults. Water activity analysis showed that the selected formula had a water activity of 0.44%. The results of all analyses showed that this extrudate was well accepted and may potentially be claimed as a high-fiber and low-fat food with long shelf life.
Keyword: analisis proksimat, makanan ekstrudat tinggi serat, kacang merah, optimasi formula, ubi ungu, formula optimisation, high-fiber extruded food, proximate analysis, purple sweet potato, red kidney bean

Judul: The Formulation of High Fiber Violet Bites Made From Purple Sweet Potato Extrudate and Black Soybean
Abstrak: Serat pangan memiliki berbagai manfaat bagi tubuh, seperti membantu dalam proses laksasi, metabolisme lemak, anti-kanker, dan anti-inflamasi. Sebanyak 95,4% masyarakat Indonesia kurang mengonsumsi serat. Ubi jalar ungu dan kedelai hitam merupakan bahan pangan yang tinggi serat dan memiliki potensi antioksidan tinggi. Penelitian ini bertujuan mendapatkan formula terbaik produk violet bites yang terbuat dari ekstrudat ubi jalar ungu dan kedelai hitam. Tahapan penelitian ini meliputi pembuatan formula, evaluasi sensori, analisis kandungan serat, analisis kandungan zat gizi makro, dan analisis kapasitas antioksidan. Penelitian ini menggunakan empat formula dengan perbedaan rasio ekstrudat ubi jalar ungu dan kedelai hitam, yaitu F1 (80:20), F2 (70:30), F3 (60:40), F4 (50:50). Formula terpilih berdasarkan hasil evaluasi sensori dan kandungan serat pangan adalah F2 dengan kandungan air 10,14%; abu 2,52%; protein 7,20%; lemak 8,89%; karbohidrat total 71,24%; serat pangan 13,50% basis basah. Kandungan serat formula terpilih lebih tinggi daripada snack bar komersial dan dapat diklaim sebagai produk tinggi serat. Dua takaran saji per hari dari formula terpilih dapat berkontribusi 10,4-15,2% terhadap kebutuhan energi dan 25,6-37,8% terhadap kebutuhan serat sehari untuk dewasa. Kapasitas antioksidan dari formula terpilih setara dengan 548,34 mg vitamin C per 100 gram., Dietary fiber had benefits for laxative process, fat metabolism, anti-cancer, and anti-inflamation. 95.4% Indonesian people consumed less fiber. Purple sweet potato and black soybean are high fiber foods and have a potency of high antioxidant capacity. This research aimed to develop the best formula of violet bites made from purple sweet potato extrudate and black soybean. This research steps include formula development, sensory evaluation, fiber analysis, macro nutrient analysis, and antioxidant capacity analysis. This research used four formulas with different ratios of purple sweet potato extrudate and black soybean, i.e F1 (80:20), F2 (70:30), F3 (60:40), F4 (50:50). The selected formula based on sensory evaluation and dietary fiber content was F2 which contains 10.14% water, 2.52% ash, 7.20% protein, 8.89% fat, 71.24% total carbohydrate, and 13.50% dietary fiber of wet basis. The dietary fiber content of the selected formula was higher than the commercial bar and might be claimed as a high fiber food. Two serving size of the selected formula can contribute 10.4-15.2% to daily energy need and 25.6-37.8% to daily dietary fiber need of adults. The antioxidant capacity of the selected formula was equivalent to 548.34 mg vitamin C per 100 gram.
Keyword: ekstrudat ubi jalar ungu, kapasitas antioksidan, kedelai hitam, serat

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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