Judul: Antioxidant Capacity of Bidara Leaves  Extract (Ziziphus spina-christi) in the Different Solvents
Abstrak: Daun bidara arab (Ziziphus spina-christi) mengandung sejumlah senyawa metabolit sekunder seperti flavonoid, alkaloid, polifenol, saponin, triterpenoid dan tannin yang berpotensi menjadi sumber antioksidan. Di Indonesia, daun bidara arab sudah mulai lazim dimanfaatkan sebagai obat herbal dengan cara perebusan daun segar. Produk-produk yang mulai dikembangkan yaitu suplemen kesehatan adan produk teh herbal daun bidara arab, namun kajian ilmiah mengenai polaritas senyawa antioksidan daun bidara arab masih terbatas. Antioksidan ada yang bersifat polar hingga bersifat non polar. Penelitian ini bertujuan mengkaji polaritas senyawa antioksidan pada daun bidara arab. Pada penelitian ini, daun bidara arab yang dikeringkan dengan fluidized bed dryer memiliki karakteristik kimia dan fisik yang lebih baik. Hasil ekstraksi menggunakan berbagai pelarut (air, etanol, etil asetat, dan heksan) menunjukkan kapasitas antioksidan tertinggi adalah pada fraksi etanol (p<0,05). Hasil ini diukur berdasarkan parameter aktivitas antioksidan DPPH, FRAP, total fenolik dan total flavonoid. Hal ini menunjukkan bahwa sebagian besar senyawa antioksidan pada daun bidara arab diperkirakan memiliki polaritas yang tinggi. Hasil uji korelasi Pearson menunjukkan korelasi sangat kuat untuk semua hasil uji. Semakin tinggi kapasitas antioksidan pada uji DPPH dan FRAP diikuti juga oleh tingginya total fenolik dan flavonoid pada sampel., Bidara leaves (Ziziphus spina-christi) contains secondary metabolites such as flavonoids, polyphenols, saponins, triterpenoids and tannins which can be a source of antioxidants. In Indonesia, bidara leaves are used as herbal medicine by boiling fresh leaves. The products that developed from bidara leaves are health supplements and herbal teas from bidara leaves, but scientific studies about the antioxidant compounds of bidara leaves are still limited. There are antioxidant components that are non-polar, semi-polar or polar. This study examines the polarity of antioxidant compounds in bidara leaves. In this study, bidara leaves dried with a fluidized bed dryer had better chemical and physical characteristics. The results of the extraction by using various solvents (water, ethanol, ethyl acetate, and hexane) showed that the highest antioxidant capacity was in the ethanol fraction (p<0.05). These results were measured based on the antioxidant activity parameters that DPPH scavenging, FRAP values, total phenolic and total flavonoids. These results indicate that most of antioxidant compounds in bidara leaves have high polarity. The results of the Pearson correlation test shows a very strong correlation for all results. The higher antioxidant capacity in the DPPH and FRAP assays will be followed by an increase in total phenolic and flavonoid in the sample.
Keyword: Antioxidant, bidara leaves, drying method, solvents

Judul: Pengaruh Metode Pengeringan dan Lama Perebusan terhadap Kapasitas Antioksidan Ekstrak Teh Daun Bidara Arab (Ziziphus spina-christi)
Abstrak: Tanaman bidara arab (Ziziphus spinachristi) mengandung beberapa senyawa fitokimia yang terdapat pada daun bidara arab yaitu alkaloid, fenol, flavonoid, saponin, kuercetin, terpenoid, dan tanin. Senyawa tersebut memiliki aktivitas antioksidan yang tinggi yang berdampak pada aktivitas antikanker, antiinflamasi, hipolipidemik. Pengolahan daun bidara biasa dilakukan dengan perebusan daun segar atau perebusan serbuk teh daun. Serbuk teh daun bidara arab memiliki umur simpan yang lebih panjang dibandingkan daun segar. Dalam penelitian ini, daun segar dikeringkan dengan 2 cara yaitu rumah kaca dan penjemuran dengan bantuan kipas angin. Tujuan penelitian ini untuk mengkaji pengaruh jenis daun bidara arab (daun segar, serbuk daun hasil pengeringan rumah kaca, serbuk daun hasil pengeringan penjemuran dengan bantuan kipas angin) dan lama perebusan daun (5, 10 dan 15 menit) dengan air mendidih (98°C) terhadap kapasitas antioksidan sari daun bidara arab. Analisis kimia yang dilakukan yaitu kadar air, kapasitas antioksidan (metode DPPH), total fenolik, total flavonoid, dan total tanin. Pada penelitian ini, daun bidara arab yang dikeringkan dengan rumah kaca diperoleh karakteristik fisik (warna) dan kimia (kapasitas antioksidan dan total fenolik) yang lebih baik. Hasil analisis ragam menunjukkan bahwa jenis daun dan lama perebusan daun bidara arab memberikan pengaruh yang nyata (α<0.05) terhadap kapasitas antioksidan, total fenolik, total flavonoid dan total tanin. Ekstrak hasil perebusan serbuk daun pengeringan rumah kaca menghasilkan kapasitas antioksidan, total fenol, total flavonoid, dan total tannin yang lebih tinggi dibandingkan ekstrak hasil perebusan daun segar maupun serbuk hasil pengeringan penjemuran dengan bantuan kipas angin. Perlakuan terbaik didasarkan pada nilai aktivitas antioksidan tertinggi, diperoleh pada serbuk daun pengeringan rumah kaca dengan lama perebusan 10 menit., The bidara arab plant (Ziziphus spinachristi) contains several phytochemical compounds found in bidara arab leaves, namely alkaloids, phenols, flavonoids, saponins, quercetin, terpenoids, and tannins. The compound has a high antioxidant activity that has an impact on anticancer, anti-inflammatory, hypolipidemic activity. The processing of bidara leaves is usually done by boiling fresh leaves or boiling leaf tea powder. The tea powder of bidara arab leaves has a longer shelf life than fresh leaves. In this study, fresh leaves were dried in 2 ways, namely greenhouse and wind drying. The purpose of this study is to examine the effect of bidara arab leaf type (fresh leaves, leaf powder from greenhouse drying, leaf powder from dry dry drying wind) and the duration of leaf boiling (5, 10 and 15 minutes) with boiling water (98 °C) on the antioxidant capacity of bidara arab leaf juice. The chemical analysis carried out is water content, antioxidant capacity (DPPH method), total phenolics, total flavonoids, and total tannins. The chemical analysis carried out is water content, antioxidant capacity (DPPH method), total phenolics, total flavonoids, and total tannins. Based of this study, the leaves of bidara arab dried with greenhouses obtained better physical (color) and chemical characteristics (antioxidant capacity and total phenolic). The results of the variety analysis showed that the type of leaf and the duration of boiling of bidara arab leaves had a noticeable influence (α<0.05) on antioxidant capacity, total phenolics, total flavonoids and total tannins. Extracts from boiling greenhouse drying leaf powders produce higher antioxidant capacity, total phenols, total flavonoids,
Keyword: Antioksidan, Bidara arab, Metode pengeringan, Lama perebusan

Judul: Model Input-output dalam Masalah Network Flow
Abstrak: Production process is a process, which is done by industry, to transform input into output. According to the type of output and its activity, industry can be classified into various sectors, which are connected to each other. Therefore, a model to analyze the connection among sections is needed. The model is known as input-output model (IO model). IO model presents an IO table, which shows informations about the transaction between goods and services in each economic sector. Furthermore, the IO model also shows that the amount of all input is the same as the amount of all output. In this paper, the transaction of each economic sector in IO table is analyzed using network flow theory. The formulated network flow problem implies that each sector represents partly as a producer and also as a consumer. This paper also solves a minimum cost circulation problem.
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