Bioactivity of casein hydrolysates fractions with reference to their in-vitro radical scavenging, hypocholesterolemic and hypotensive properties
The bioactivities of casein hydrolysates for hypocholesterolemic (HC) and hypotensive (HT) properties, using Angiotensin Converting Enzyme (ACE) inhibition as an indicator, as well as antioxidant properties have been investigated. Sodium caseinate was used as the source for the production of bioactive peptides by enzymatic hydrolysis using trypsin at pH 7.5 and a combination of pepsin at pH 2.0 followed by trypsin (P+T) at different time intervals and up to 4 hours.
Crude casein hydrolysate (CH) was further fractionated by membrane separation technique, ultrafiltration, using two membranes with two different molecular weight cut-off at 10 kDa and 1 kDa. The crude hydrolysate was compared with the two collected permeates; one containing a mixture of peptides with molecular weight below 10 kDa and the second with peptides below 1 kDa. In general, the results indicated that the higher level of hydrolysis exhibited higher bioactivities for all the tested samples. Hypocholesterolemic effect of the hydrolysates and the permeates, CH, 10 kDa and 1 kDa, using trypsin only for 4 h shown to reduce cholesterol level by 39.5, 50.1 and 69.6%, respectively. On the other hand, the hydrolysates and the permeates from the combined action of pepsin and trypsin showed higher cholesterol reduction of 44.9, 52.2 and 87 .0%, respectively.
ACE inhibition activities of the hydrolystate and its permeates, CH, 10 kDa and 1 kDa from trypsin hydrolysis after 4 hours were 18.9, 29.7 and 5l.4%, respectively. ACE inhibition activities were greatly increased when the combined P+T were used and exhibited 31.1, 52.7 and 82.4% inhibitions, respectively.
The antioxidant activity of the three samples (crude casein hydrolysate, 10 kDa & 1 kDa permeates) after 4h hydrolysis using trypsin showed radical scavenging activities of 13.7, 17.3 and 24.4% respectively. However, when using the combined enzymes P+T, the activities were reduced to 13.1, 15.5 and 19.6% respectively.
- School of Sport and Health Sciences