Milk protein is a well-known precursor protein for the generation of bioactive peptides using lactic acid bacteria. This study investigated the antioxidant activity of bovine casein hydrolysate after ...fermentation with Bifidobacterium longum KACC91563 using the 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay and total phenolic content (TPC). The antioxidant activities of the 24-h and 48-h hydrolysates were higher than that of the 4-h hydrolysate (2,045.5 and 1,629.3μM gallic acid equivalents, respectively, vs. 40.3μM) in the ABTS assay. In contrast, TPC values showed activities of 43.2 and 52.4μM gallic acid equivalents for the 4-h and 24-h hydrolysates, respectively. Three fractions (≥10kDa, ≥3 but <10kDa, and <3kDa) were separated from the 24-h hydrolysate by ultrafiltration. Among these fractions, the <3kDa fraction exhibited the highest antioxidant activity (936.7μM) compared with the other fractions (42.1 and 34.2μM for >10kDa and 3–10kDa fractions, respectively). Through liquid chromatography-electrospray ionization-tandem mass spectrometry analysis, 2 peptides, VLSLSQSKVLPVPQK and VLSLSQSKVLPVPQKAVPYPQRDMPIQA, containing the fragment VLPVPQ that has antioxidant properties, were identified in the <3kDa fraction after 24h of hydrolysis. The present study demonstrates the possibility of antioxidant peptide production from bovine casein using Bifidobacterium longum.
The Particle Detector (PD) experiment aboard the geostationary satellite GEO-KOMPSAT-2A (GK2A) measures populations of electrons and positive ions in the Earth’s geostationary orbit at a geographic ...longitude of
128.2
∘
E
, inclination of
0
∘
and a mean orbital radius of 6.6 Earth radii (
R
E
). The PD experiment consists of three sensors with different viewing angles relative to the spacecraft. Each sensor consists of two telescopes that are mechanically configured back-to-back with a field-of-view of
20
∘
×
20
∘
and measures electrons and ions, using silicon detectors equipped with foils and magnets for the separation of ions and electrons. The energy ranges of the sensor for electrons and ions are 100–3800 keV and 148–22500 keV, respectively. A particular emphasis on electron measurement is given by allocating 48 energy bins in the measured energy range, whereas 22 energy bins are allocated for ion measurements. This unprecedented energy resolution of
Δ
E
/
E
in the range 5–25% for the electron and ion flux measurements is acquired every three seconds with cyclic polling of each sensor every second to provide an effective temporal resolution of one second. Together with the magnetometer aboard the spacecraft, the PD experiment will provide quantitative observations that will enable improved understanding of the adiabatic and nonadiabatic dynamics of the Earth’s magnetosphere for space weather studies at geostationary orbits from the vantage point of a far-east longitude.
PDF
