Judul: Produksi Batch dan Kontinu Peptida Bioaktif dari Ikan Gabus
Abstrak: There is a high demand for functional foods. Bioactive peptides are potential ingredients in functional food development due to their functional properties, such as antioxidant activity. Snakehead fish (Channa striata) extract (SHFE) is a suitable source of parent proteins for producing bioactive peptides due to its high protein content and hydrophobic peptides. This study aimed to investigate the batch and continuous processes for producing SHFE-based bioactive peptides. Proteases such as Alcalase and Neutrase were used to hydrolyze the parent proteins. The enzymatic membrane reactor facilitated the continuous production of bioactive peptides from SHFE. Bioactive peptides from SHFE that exhibit antioxidant activity can be produced through enzymatic hydrolysis using Alcalase and Neutrase, either in a batch or continuous process. A substrate concentration of 3%, and enzyme-to-substrate ratio of 10%, using Alcalase were selected as the optimum conditions based on their antioxidant activity measured by DPPH and FRAP methods. Based on the calculated fouling rate of continuous operation under the obtained optimum conditions, the production of SHFE-based peptides has the potential to be performed continuously in the long term. Permeate filtration using a 2-kDa membrane increased the antioxidant activity, as indicated by a smaller DPPH IC50 value (i.e., 0.23 mg protein/ml). Further research is needed to identify the specific peptide sequences responsible for antioxidant activity and other bioactivities that might be exhibited by the SHFE-based bioactive peptides. This study is expected to increase the production of functional ingredients from snakehead fish.
Keyword: antioxidant, bioactive peptides, enzymatic membrane reactor, snakehead fish

Judul: Continuous Production Bioactive Peptides from Koro Benguk Protein Concentrate with Alkalase Enzyme in Enzymatic Membrane Reactor
Abstrak: Peptida bioaktif yang berasal dari sumber protein dapat dijadikan sebagai sumber untuk menghasilkan pangan fungsional yang memiliki efek terhadap kesehatan. Salah satu protein nabati yang memiliki potensi sebagai sumber peptida bioaktif adalah koro benguk. Penelitian ini bertujuan memproduksi peptida bioaktif koro benguk secara kontinu dengan menggunakan reaktor membran enzimatis dengan kondisi optimum. Peptida bioaktif yang memiliki aktivitas antioksidan dapat dihasilkan dengan menghidrolisis sumber protein dengan enzim alkalase yang kemudian diekstraksi menggunakan reaktor membran enzimatis secara kontinu. Kondisi optimum untuk menghasilkan peptida adalah [E]/[S] sebesar 5%, pH 7,5, dan residence time 12 jam menggunakan membran 5 kDa MWCO dengan nilai kapasitas antioksidan metode DPPH sebesar 4,73x10-2 ± 1,37x10-3 µg AEAC/mL, metode FRAP sebesar 2,57x10-2 ± 1,12x10-3 µg AEAC/mL, dan persen inhibisi sebesar 78,56 ± 0,63. Permeat dengan fraksi protein <2 kDa dengan nilai IC50 terbaik sebesar 1,22x10-5 ± 4,67x10-6 mg/mL., Bioactive peptides derived from protein sources can be used as a source to produce functional food that has an effect on health. One of the vegetable proteins that has the potential as a source of bioactive peptides is velvet bean. This study aims to produce bioactive koro benguk peptides continuously using an enzymatic membrane reactor with optimum conditions. Bioactive peptides that have antioxidant activity can be produced by hydrolyzing protein sources with alkalase enzymes which are then extracted using an enzymatic membrane reactor continuously. The optimum conditions for producing peptides were [E]/[S] of 5%, pH 7.5, and residence time of 12 hours using a 5 kDa MWCO membrane with an antioxidant capacity value of the DPPH method of 4,73x10-2 ± 1,37x10-3 µg AEAC/mL, the FRAP method was 2,57x10-2 ± 1,12x10-3 µg AEAC/mL, and the percent inhibition was 78,56 ± 0,63. Permeate with a protein fraction <2 kDa with the best IC50 value of 1,22x10-5 ± 4,67x10-6 mg/mL.
Keyword: alcalase, antioxidant, bioactive peptide, membrane reactor, velvet bean

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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