Effects of high hydrostatic pressure, ultraviolet light-C, and far-infrared treatments on the digestibility, antioxidant and antihypertensive activity of α-casein

Structural and oxidative modifications, and antioxidant activity of β-lactoglobulin treated by ultraviolet light-C and ultrasound

“…Ten milliliters of protein solutions with concentration of 2.0 mg/mL were placed in a Petri dish (90 mm diameter, 15 mm height), giving a depth of~1 mm, and exposed to UV-C light for 15 or 30 min. [12] Ultrasound treatment Ultrasound treatment was carried out using a high-intensity ultrasound liquid processor (Zealway, China) operating at 40 kHz with an input power of 900 W. A 50 mL (2 mg/mL) of protein solutions in a 100-mL beaker were placed into the ultrasonic tank and treated for 15 or 30 min. [21] Water temperature fluctuation inside the ultrasonic bath was lower than 2°C during the treatment.…”

“…[12] A 1 mL (2 mg/mL) of β-Lg sample was added to sodium phosphate buffer (2.5 mL, 0.2 M, pH 6.6) and potassium ferricyanide (2.5 mL, 1% solution), incubated at 50°C for 20 min, and then trichloroacetic acid (2.5 mL, 10%) was added. After centrifugation at 3000 rpm for 10 min (Centorion K24OR-2003 refrigerated centrifuge), 2.5 mL of the upper layer was mixed with 2.5 mL deionised water and 0.5 mL ferric chloride (0.1% solution).…”

“…Increased FSH contents were also reported in α-casein after UV-C treatment and in ovalbumin treated with ultrasound. [12,19] Like pulsed light or heat denaturation process, UV-C or ultrasound may induce structure modifications including protein unfolding, which leads to an increase of the exposed hydrophobic groups and a reduction of S-S bonds. [34] The decrease in TSH suggested that β-Lg became progressively denatured and unfolded as heating time increased.…”

“…[25] Antioxidant activity DPPH is a stable free radical that can accept an electron or hydrogen radical, and is often used as a substrate to evaluate antioxidant activity of peptides and protein hydrolysates. [12] Higher DPPH radical scavenging activities indicate a higher antioxidant activity. As shown in Table 2, ultrasound treatments significantly decreased the DPPH radical scavenging activity compared with the control.…”

“…[10] Our previous studies have indicated the effects of high hydrostatic pressure, UV-C (11.8 W m ), and far-infrared treatments on the allergenicity, digestibility, and antioxidant and antihypertensive activities of α-casein. [11,12] Changes in the primary structure, resulting in dityrosine, N-formylkynurenine, and carbonylation products, have been observed on β-Lg, β-casein or α-lactalbumin after 24 h of UV-C (2.34 × 10 19 quanta s ) exposure. [10] UV-C exposure (10.6 and 63.7 kJ m ) has also induced the development of large protein aggregates by disulfide exchange and protein backbone cleavage in egg white.…”