Skin waste from tuna processing needs to be utilized, such as extraction of its collagen and gelatin. Their functional properties can be improved by enzymatic hydrolysis for conversion to peptides. Thus, the research objectives were to examine the characteristics and antioxidant activity of collagen, gelatin, and the derived peptide from yellowfin tuna skin. Collagen was extracted using 0.75 M acetic acid at 4 °C, while gelatin was prepared using 0.25% citric acid and extracted at 65 °C. Hydrolysis was carried out with 2% Alcalase, followed by fractionation with a molecular weight cut off sieve for both collagen and gelatin. Collagen yield was 22.6% with pH value of 6.63 and whiteness of 96.7%. Gelatin yield was 20.0% with pH value of 4.94 and whiteness of 51.0%. Hydrolysis for three hours resulted in 52.7% and 45.2% degree of hydrolysis for collagen and gelatin, respectively. The molecular weights of collagen peptides ranged from 2.94 to 11.93 kDa, while those of gelatin peptides ranged from 3.54 to 16,620 kDa. Antioxidant activities of these peptides were higher than those before hydrolysis. The high antioxidant activity (IC50) of collagen peptides were found in <3, 3–10, and 10–30 kDa fractions as well as in the gelatin peptides.

No abstract

Deterioration of fish quality affects the accumulation of metabolites, flavor changes, the formation of volatile components, as well as an increase in the number of bacteria. Chilling temperature storage is the way to maintain the quality of fish. This research was aimed to determine quality changes of little tuna (Euthynnus affinis) through organoleptic test, chemical properties and protein analysis during chilling temperature storage. Observations were conducted every 48 hours for 14 days. The parameters observed were proximate, organoleptic, pH, water-soluble protein, metmyoglobin level, and its molecular weight. Little tuna was still in fresh criteria on the 4th day with organoleptic value of 7 and was spoiled on the 10th day. The chemical composition of the fish changed during storage, increased in moisture content, decreased protein levels, and increased ash content. The values of water-soluble protein decreased during the storage while the metmyoglobin level increased during storage. In conclusion, little tuna suffered a setback in quality during 14 days of chilling temperature storage. The storage time influenced the level of water-soluble protein and the level of metmyoglobin produced.

Histamin merupakan senyawa amin biologis yang dapat terbentuk dari histidin bebas dalam daging ikan pada fase post rigor. Laju pertumbuhan histamin dapat diperlambat dengan cara menjaga mutu ikan menggunakan suhu dingin. Tujuan dari penelitian ini adalah menentukan lama waktu penyimpanan, perubahan kimia dan mikrobiologis ikan tongkol Thunnus tonggol serta waktu terdeteksinya gen hdc selama penyimpanan suhu 8±3°C. Rancangan penelitian yang digunakan adalah rancangan acak lengkap (RAL) dengan parameter perbedaan waktu penyimpanan ikan (1,2,3,4,5,6,7 hari) dan perbandingan es 1:1. Hasil penelitian menunjukkan ikan tongkol abu-abu mengalami kemunduran mutu selama 7 hari penyimpanan. Nilai organoleptik dan pH mengalami penurunan selama penyimpanan dan pada hari ketujuh ikan berada pada fase rigormortis. Nilai TVB dan TPC meningkat selama penyimpanan dan pada penyimpanan hari keenam sudah melewati batas aman untuk dikonsumsi. Kadar histamin pada hari ketujuh yaitu 1,96 ppm. DNA berhasil di-isolasi dan terdeteksi gen hdc, namun hasil amplifikasi belum efektif, sehingga diperlukan optimalisasi metode PCR. Profil protein yang terbentuk selama penyimpanan berdasarkan hasil SDS-PAGE mulai terpisah karena adanya aktivitas enzim katepsin.

Seahorse (Hippocampus spp.) is a species of unique marine biota showing male pregnancy. The purpose of this study was to identify seahorse species (Hippocampus spp.) through molecular approach by DNA barcoding using COI gene marker, determine the potential of seahorse as an antioxidant and an indicator of immunomodulatory properties. The research results showed the nucleotide sequences of DNA sample H1, H2, and H6 identified as H. kuda, while H3, H4, and H5 were identified as H. comes with the level of identity (homology) as much as 98%-99%. In general, the results of antioxidant activity in seahorse samples can be used as a source of natural antioxidants, namely in the form of seahorse hydrolysates and seahorse ethanol extract (IC50 50-100 ppm). The highest cell proliferation activity was from the seahorse powder group at a concentration of 250 ppm with the value of OD (Optical Density) of 0.227±0.002 and SI (Stimulant Index) of 120.74%. These results indicated that seahorses potentially have indicators of immunomodulators properties.