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 of Bioactive Peptides from Mung Bean Concentrate using Alcalase Enzyme in an Enzymatic Membrane Reactor
Abstrak: Consuming foods containing antioxidants may help in reducing the risk of developing diseases. Peptides from mung beans have shown to exhibit antioxidative properties, thus may be a potential ingredient in the production of functional foods. Mung bean based bioactive peptides can be continuously produced through enzymatic hydrolysis using alcalase in an enzymatic membrane reactor. The research was divided into three stages namely isolation and characterisation of mung bean protein concentrate, continuous production of bioactive peptides with parameter variations (enzyme-substrate ratio, pH and residence time) and IC50 analysis performed on the permeate produced under optimum conditions. The permeate produced with the optimum conditions of 5% enzyme-substrate ratio, pH 7.5 and 10-hour residence time had the best antioxidant capacities of 28.2069 μg AEAC/mL (DPPH), 16.1442 μg AEAC/mL (FRAP), 91.6802% (ABTS). The < 2 kDa fraction had the best IC50 value of 0.2026 mg protein/mL.
Keyword: Alcalase, Antioxidant, Bioactive Peptide, Enzymatic Membrane Reactor, Mung 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.
Keyword: