Judul: Improving sardines (Sardinella sp.) oil quality using centrifugation and synthetic adsorbent
Abstrak: Sardines (Sardinella sp.) was a by-product of flouring and canning industry where sardines are known contain more than 10% fat and most of the fat that was stored in the belly cavity (Moeljanto 2010). Purification is needed to get fish oil with food quality, so it is safe to be consumed. The purpose of this research were (1) characterize and determine the best fish oil taken from different locations; (2) determine the best purification treatment of centrifugation, adding synthetic adsorbent and combination; (3) determine optimization treatment of centrifugation and adding synthetic adsorbent using response surface method (RSM). Fish oil taken from different locations, Banyuwangi and Pekalongan. The best fish oil was taken from Pekalongan with composition of an unsaturated fatty acid 40.17% and saturated fatty acid 31.16%, with free fatty acids value 3.94 %, peroxide value 5 meq/kg, anisidin value 0.88 meq/kg and totox value 10.88 meq/kg. Purification by centrifugation best treatment was 10,500 rpm for 30 minutes. Purification by adsorbent synthetic best treatment was adding atapulgite 3% and bentonite 3%. Purification by combination centrifugation and adding synthetic adsorbent best treatment was centrifugation at 10,500 rpm for 30 minutes combined atapulgite 3% and bentonite 3%. The response surface method optimization best treatment was centrifugation at 9,494.89 rpm for 31.48 minute combined atapulgite 3% and bentonite 3% with free fatty acids value 4.07%, peroxide value 2.97 meq/kg, anisidin value 0.81 meq/kg and total oxidation value 6.32 meq/kg. An increase in percent of fish oil light transmission at different wave lengths by centrifugation and adding synthetic adsorbent. The best transmission values obtained at the combination synthetic adsorbent of bentonite and atapulgite on fish oil which is centrifuged first with 10,500 rpm for 30 minutes.
Keyword: adsorbent, centrifugation, fish oil, response surface method, Sardinella sp.

Judul: Pemurnian Minyak Ikan Sardin (Sardinella sp.): Sentrifugasi dan Adsorben Bentonit
Abstrak: Centrifugation and purification using adsorbents is one example of a fish oil refining techniques applied to reduce impurities of fish oil. The study aimed to determine the sardine oil quality before treatment, to determine yield of fish oil after centrifugation treatment, to determine the influence of centrifugation speed and bentonite concentration on sardine oil quality. Level of free fatty acids and peroxide value before purification was 35.53% and 170 meq/kg. Yield of fish oil after centrifugation treatment has been ranged from 17.42±3.56 to 76.33±0.21%. The best treatment which could reduce the peroxide value and total oxidation was a treatment with centrifugation speed at 6500 rpm and bentonite concentration at 3%. Peroxide value and total oxidation of its treatment was 25.00±0.00 meq/kg and 51.43±0.01 meq/kg. The lowest value of p-anisidine was 1.29±0.05 meq/kg and its value could be found in a treatment with centrifugation speed at 4500 rpm and bentonite concentration at 5%. The level of free fatty acids after purification process was ranged from 27.35 to 34.69%. Oil clarity tended to increase with the increase of speed centrifugation and adsorbent concentration.
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Judul: Closed Knight’s Tour pada Papan Catur Berbentuk Persegi Panjang dengan Ukuran Maksimal 8 × 8
Abstrak: Closed Knight’s Tour merupakan langkah kuda yang mengunjungi setiap kotak pada papan catur tepat satu kali dengan langkah kuda berawal dan berakhir pada kotak yang sama. Graf yang terbentuk dari closed knight’s tour dinotasikan sebagai graf G(m,n), dengan m adalah banyaknya baris dan n adalah banyaknya kolom. Graf tersebut memuat Hamiltonian cycle. Sebuah graf terhubung G adalah graf bipartite jika dan hanya jika graf tersebut tidak memiliki cycle dengan panjang ganjil. Papan catur yang memenuhi syarat cukup untuk memiliki closed knight’s tour adalah papan catur berukuran 5 × 6, 5 × 8, 6 × 6, 6 × 7, 6 × 8, 7 × 8, dan 8 × 8.
Keyword: bipartite, closed knight’s tour, hamiltonian cycle, knight’s tour, teori graf