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Effect of mono- and dual frequency power ultrasound assisted enzymolysis on the degree of hydrolysis and ACE inhibitory activity of Stevia protein hydrolysates

Mohammed Abdalbasit A. Gasmalla
Abubakr Musa
Faisal N. Awad
Habtamu Admassu
Haile Ma


Purpose: To study the effects of ultrasound pretreatment at different frequencies and working modes, including mono frequency ultrasound (MFU) and dual-frequency ultrasound (DFU), on the degree of hydrolysis (DH) and angiotensin-I-converting enzyme (ACE) inhibitory effect of Stevia protein (SP).

Methods: Protein from Stevia leaves was extracted by water (50 g suspended in 1000 mL). The hydrolysis of stevia protein extract (SPE) was carried out using alcalase at 5 % enzyme substrate (E/S) ratio. A study was then carried out to investigate its microstructure and morphology using scanning electron microscopy (SEM).

Results: The results showed that ultrasound pretreatment did not increase DH of SP significantly (p > 0.05). However, the highest ACE inhibitory activity of stevia protein hydrolysate was obtained at DFU level (20/50 KHz). Overall, ultrasonic frequency mode had a significant influence on ACE inhibitory activity.

Conclusion: The frequency selection of ultrasound pretreatment of SP is essential for the preparation of ACE inhibitory peptide.

Journal Identifiers

eISSN: 1596-9827
print ISSN: 1596-5996