Judul: Diversity of Fish Terasi Collected from Various Regions in Indonesia Based on Physicochemical Characteristics
Abstrak: Terasi, a fish or shrimp paste, has been studied as a naturally fermented product with delectable flavor that is frequently used as a seasoning for food. Besides, terasi is frequently used in Indonesian cuisine to enhance the flavor. There are various places in Indonesia where fish paste is produced, and each producer may use a different manufacturing method in making terasi its-self. Variations in the materials, salt concentration, duration of fermentation and drying give impacts on the physicochemical characteristics such as proximate, NaCl, titratable acids, nucleotides, total amino acids, free glutamic acid, pH, activity of water, texture, color and FTIR profile. The manufacturing procedures of fish paste production include drying the raw materials, grinding the dried components, adding the water, and fermentation from 2 weeks to 8 months. The unique and complex flavor of the paste is produced by microbial growths which allow enzymatic reactions during fermentation. Information regarding the chemical and physical characteristics of fish terasi from various regions in Indonesia is still limited. The objective of this study was to characterize fish terasi products based on the physicochemical attributes and to map the chemical characteristics through multivariate analysis to determine the diversity of fish terasi. Proximate composition, NaCl, total titratable acid, pH, total amino acids, free glutamic acid, nucleotides (AMP and IMP), texture, color and water activity of ten samples of fish terasi collected from different producers in Indonesia, were analyzed. Fish terasi samples used in this study had the average of proximate composition, such as moisture content of 29.77% (wb), ash content of 22.70% (wb), fat content 4.08%, protein content of 33.97% (wb) and carbohydrate of 10.68% (wb). Additionally, the average of free glutamic acid, adenosine monophosphate and (AMP) and inosine monophosphate (IMP) were 0.14% (wb), 0.72% (wb), and 0.17% (wb) respectively. Furthermore, the average of other chemical compositions such as NaCl, total titratable acid was 11.45% (wb) and 3.27% (wb) respectively. Besides, the average of pH and water activity (aw) obtained were 6.67 and 0.7 respectively. Therefore, fish terasi is classified into medium risk food. Fish terasi samples were divided into four groups based on principal component analysis (PCA) on proximate composition data: samples from Rembang (Central Java), Majalengka and Pangandaran (West Java), and Sumenep (East Java) characterized by fat content; samples from Indramayu (West Java), Jember and Sidorajo (East Java) characterized by protein content; samples from Lampung (Southern Sumatera) and Bekasi (The samples classified according to protein concentration were grouped together in the mapping result based on FTIR spectra (400-1500 cm-1). Umami compound mapping revealed that sample from Majalengka was defined by AMP and IMP, whereas samples from Jember, Sumenep, and Pangandaran were characterized by free glutamic acid. The umami taste of fish terasi samples was predicted from equivalent umami concentration (EUC) in g free Glu per 100 g terasi (wet basis). Sample from Majalengka showed the highest EUC (470), followed by that from Indramayu (297), Ogan Ilir (207) and Sidoarjo (154). Other samples had EUC lower than 100. Therefore, samples having relatively high proteins and nucleotides are potential for umami research. Keywords: fish terasi, fish paste,
Keyword: Fish Terasi, HPLC, FTIR, Amino Acids, Free Glutamic Acid, AMP & IMP, EUC

Judul: Influence of Fermentation Time on Tropomyosin Content as Allergen Protein of Shrimp Paste (Terasi Udang Rebon)
Abstrak: Terasi udang merupakan produk olahan hasil perikanan dengan bahan baku udang rebon atau udang segar, atau kering atau campurannya yang difermentasi. Penelitian ini bertujuan menentukan pengaruh lama waktu fermentasi terhadap karakteristik terasi dan kandungan protein alergen tropomiosin. Analisis protein alergen tropomiosin menggunakan metode SDS-PAGE dan dihitung kandungannya melalui intensitas pita tropomiosin. Kadar protein pada produk akhir terasi sebesar 16.74% pada terasi 7H, 16.46% pada terasi 14H, dan 16.03% pada terasi 21H. Hasil pengukuran protein terlarut pada sampel terasi 7H, 14H, dan 21H berturut-turut sebesar 1.504, 1.106, dan 1.069 mg/mL. Penilaian organoleptik terasi memiliki rata-rata nilai berkisar 6 – 7 yang memiliki arti cukup spesifik jenis terasi. Pita bobot molekul hasil analisis SDS-PAGE memperoleh hasil protein alergen tropomiosin berkisar 34,41 – 35,68 kDa. Ketebalan intensitas pita protein tropomiosin semakin memudar pada sampel 14H dan 21H sehingga konsentrasi tropomiosin semakin berkurang pada waktu 14H dan 21H., Shrimp paste (terasi) is a processed fishery product made from raw, fresh or dried small shrimp or its fermented mixture. This study aims to determine the effect of fermentation time on the characteristics of shrimp paste and the content of tropomyosin allergen protein. Tropomyosin allergen protein analyzed using SDS- PAGE method and its content was calculated by the intensity of the tropomyosin band. The protein content in the final shrimp paste product was 16.74% for 7H shrimp paste, 16.46% for 14H shrimp paste, and 16.03% for 21H shrimp paste. The highest results of dissolved protein content obtained in fresh rebon shrimp samples were at 3,013 mg/mL, 7H, 14H, and 21H shrimp paste at 1,504, 1,106, and 1,069 mg/mL, respectively. The organoleptic results of shrimp paste have an average value ranging 6 to 7 which have a fairly specific meaning for the type of shrimp paste. Molecular weight bands from SDS-PAGE analysis obtained tropomiosin allergen protein ranges from 34.41 – 35.68 kDa. The thickness of the tropomyosin protein band intensity faded in sample 14H and 21H suggesting the tropomyosin concentration decreases at 14H and 21H.
Keyword: Alergen tropomiosin, Fermentasi, Terasi udang, fermentation, shrimp paste, tropomyosin allergen

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