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, Chemical, and Microbiological Characteristics of Spirulina Snack Bars During Storage with Different Types of Food Packaging
Abstrak: Snack bar spirulina dikategorikan sebagai produk makanan ringan siap santap dengan beragam kandungan nutrisi dan komponen bioaktif (superfood). Penyerapan uap air dan oksigen dari lingkungan dapat mengakibatkan perubahan parameter fisik, kimiawi, dan mikrobiologi selama penyimpanan. Pengendalian penurunan mutu produk pangan dapat dicegah dengan bantuin faktor ekstrinsik, misalnya jenis kemasan dan suhu penyimpanan. Penelitian ini bertujuan menentukan jenis kemasan dan suhu penyimpanan yang terbaik dalam mencegah deteriorasi komponen fenol pada snack bar spirulina, mengetahui pengaruh kedua faktor ekstrinsik terhadap parameter fisik dan kimiawi, serta mengetahui total mikroba selama penyimpanan. Pemilihan kemasan yang digunakan untuk penelitian ini, yaitu metallized film, HDPE dengan standing pouch dan metallized film dengan art carton. Snack bar spirulina yang sudah dikemas disimpan pada suhu ruang (25−29 ºC) dan suhu dingin (0−6 ºC) selama tiga bulan. Perlakuan terbaik berasal dari snack bar spirulina yang dikemas menggunakan metallized film dengan art carton pada suhu dingin dengan perubahan total fenol dari 25,06 mg GAE/g menjadi 16,02 mg GAE/g selama tiga bulan penyimpanan. Perlakuan perbedaan jenis kemasan dan suhu penyimpanan berpengaruh nyata terhadap komposisi kimia, perubahan warna, lightness, dan profil tekstur. Total mikroba snack bar spirulina memenuhi persyaratan mutu SNI 8416:2018., Quality spirulina snack bars may decrease due to moisture and oxygen absorption from the environment. These events cause changes in physical, chemical, and microbiological parameters. Deteriorative reaction in snack bars can controlled by many extrinsic factors, such as the type of packaging and storage temperature. This study aims to determine the best type of packaging and storage temperature to prevent the deterioration of polyphenols from product, determine the effect of both extrinsic factors on physical and chemical, and ensure microbiological parameter met quality requirements during storage. The selection of packaging used for this study, namely metallized film, HDPE with a standing pouch, and metallized film with an art carton. Packaged spirulina snack bars are stored at room temperature (25−29 ºC) and cold temperature (0−6 ºC) for three months. Product packaged using metallized film with an art carton at cold temperatures was the best treatment because it maintained the polyphenol content for up to three months of storage from 25.06 mg GAE/g to 16.02 mg GAE/g. Both extrinsic factors significantly affect the chemical composition, color different, lightness, and texture profile. The total microbes of spirulina snack bars met the quality requirements of SNI 8416:2018.
Keyword: deterioration, food packaging, snack ready-to-eat, spirulina, total phenolic content

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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