2.2. Multi-frequency power ultrasound pretreatment of CGM
Prior to the enzymolysis reaction, the CGM was pretreated by multi-frequency power ultrasound viz. sweeping frequency and pulsed ultrasound (SFPU) and sequential dual frequency ultrasound (SDFU). The traditional enzymolysis (Control) was conducted with AG 1879 magnetic stirring apparatus instead of ultrasound under the same conditions. All experiments were carried out in triplicate.
2.2.1. Ultrasound treatment with sweeping frequency and pulsed ultrasound (SFPU)
Fig. 1. The multi-frequency power ultrasound. (a) The sweeping frequency and pulsed ultrasound (SFPU), (b) sweeping frequency, (c) the sequential dual frequency ultrasound (SDFU), (d) sequential mode.Figure optionsDownload full-size imageDownload as PowerPoint slide
2.2.2. Ultrasound treatment with sequential dual frequency ultrasound (SDFU)
2.3. Enzymolysis of corn gluten meal
The enzymolysis apparatus consisted of a digital thermostat water bath (DK-S26, JingHong experimental apparatus Co., Shanghai, China), a pH meter (FE-20, Mettler Toledo Co., Shanghai, China) and an impeller-agitator (JJ-1, ZhongDa instrument Co., Jiangsu, China) at a speed of 100 r/min. After 10 min preheating at 50 °C, the solution was adjusted to pH 9.0, and 1 mL of enzyme was added to initial the reaction. The pH was maintained by continuous addition of 0.5 M NaOH during the enzymolysis process. The enzymolysis time was 60 min and the reaction was terminated by boiling the mixtures for 10 min and then centrifuged at 5030×g for 15 min after cooling to room temperature.