Effects of microwave and ultrasound pretreatments on enzymolysis of milk protein concentrate with different enzymes

Abstract

Milk protein concentrate was pretreated either by microwave irradiation or by ultrasound before initiation of 3-h enzymatic hydrolysis. The duration of pretreatment ranged from 1 to 8 min at a power level of 800 W, with the control not being subjected to any pretreatment, and five enzymes (Alcalase, Trypsin, Neutrase, Alkaline Protease and Flavourzyme) were employed. The effects of microwave and ultrasound pretreatments on the kinetics and degree of hydrolysis, protein solubility, bitterness and angiotensinconverting enzyme inhibitory activity were evaluated. Pretreatments increased the degree of hydrolysis and stabilised the solubility of the hydrolysates but could not significantly reduce bitterness of the hydrolysates The angiotensin-converting enzyme inhibitory activity of the hydrolysates were improved with 5-min ultrasound-pretreated Neutrase hydrolysates giving IC 50 value of 0.23 mg mL À1 . Kinetic parameters showed improved catalytic efficiencies. Pretreatments of milk protein concentrates with either microwave or ultrasound significantly improve the bioactivity and functional characteristics of the resulting hydrolysates. Enzyme hydrolysis of MPC H. Uluko et al. Enzyme hydrolysis of MPC H. Uluko et al. Enzyme hydrolysis of MPC H. Uluko et al. 2254 Enzyme hydrolysis of MPC H. Uluko et al. 2255 Enzyme hydrolysis of MPC H. Uluko et al. Enzyme hydrolysis of MPC H. Uluko et al.

Impact of Power Ultrasound on Antihypertensive Activity, Functional Properties, and Thermal Stability of Rapeseed Protein Hydrolysates

“…It has been reported that sonication could favor the enlargement of soluble protein aggregates from insoluble precipitates [58]. Higher solubility after sonication is also reported some other researchers [9,27,53,54,59]. It can be concluded that rapeseed protein pretreatment by ultrasound is an attractive approach improvement of functional characteristics.…”

“…The solutions were incubated and stirred continuously using magnetic stirrer for 30 min in a thermostat water bath at 40 ∘ C to ensure complete dissolution and then subjected to cool to room temperature. After that, the solutions were given treatment using probe-type sonicator ( Figure 1) (GA98-IID, Shanghai Biotechnology Co., Wuxi, China) at 20 kHz with a 1.5 cm flat tip probe (diameter of 2 cm) which was immersed into the rapeseed protein solution for different irradiation time (3,6,9,12,15, and 18 min) and at different powers (200, 400, 600, 800, 1000, and 1200 watts).…”

“…The method described by [9] was applied for the protein solubility determination with slight modification. In brief, in 100 mL distilled water 1 mL of rapeseed protein hydrolysate was mixed and the pH of the subsequent mixture was adjusted to the pH 7.0 either 1 M NaOH or 1 N HCl, and then the mixture was stirred at room temperature for 30 min and transferred to a 20 mL centrifuge tubes and centrifuged at 10,000 ×g at 20 ∘ C for 15 min.…”

“…Furthermore, it is suggested that the rapeseed protein is an attractive source of bioactive compounds [5]. According to the existing literature, the enzymatic hydrolysis with proteases (specific or nonspecific) has been a most important process to the production of antioxidative and ACE inhibitory peptides from food proteins [8][9][10]. The release of bioactive peptides from proteins by traditional enzymatic hydrolysis is influenced by several factors such as enzymatic substrate ratios, pH, hydrolysis time, and hydrolysis temperature [11].…”

Impact of ultrasound on egg white proteins as a pretreatment for functional hydrolysates production

“…Although the potential of heat pretreatment to improve enzymatic hydrolysis of EWPs has been explored widely in the last decade [24], such method leads to destruction of some functional properties of egg white, such as gelling and foaming, which are often desirable for food manufacture [13]. Ultrasound pretreatment has also been used to improve the hydrolysis of several proteins [25] and in turn improve the production of angiotensin-converting enzyme (ACE) inhibitory peptides, by causing unfolding of protein chains and thus release possible peptides that are responsible for ACE-inhibitory activity [26]. Despite the promising effects of sonication alone or in combination with heat or pressure on a laboratory scale, there is limited information on the hydrolysis of EWPs from different ultrasound treatments and proteolytic enzyme systems.…”