ACE-inhibitory peptide from rohu fish waste: Optimisation of ultrasound and microwave assisted enzymatic extraction using response surface methodology

Abstract

Anti-hypertensive [angiotensin-I converting cnzyme (ACE) inhibitory (ACEi) peptides are enzymatically extracted from biological material. The high cost of enzymes, low peptide yield and long hydrolysis time in enzymatic extraction paved the way for alternative ultrasound assisted enzymatic extraction (UAEE) and microwave-assisted enzymatic extraction (MAEE). In this study, rohu (Labeo rohita) fish wastes were homogenised and treated with ultrasound (40 kHz) and microwave (2450 MHz) before enzymatic hydrolysis using optimised concentration of alcalase® for the extraction of ACEi. The UAEE (sonication temperature: 30-70; optimum: 57.88ºC and time: 10-50; optimum: 63.4 min) and MAEE (microwave power: 180-900, optimum: 335.23 W and time 5-25, optimum: 15 min) were studied for their effect on degree of hydrolysis (DH), ACE inhibition (ACEi) and peptide yield (PY). The efficiency obtained by UAEE (5%) was higher than MAEE (4%) in terms of ACEi. In contrast, MAEE showed higher efficiency with respect to DH and PY (7 and 6.5 %, respectively) than UAEE (2.5 and 4%, respectively). The study indicated that UAEE and MAEE are efficient methods for extraction of ACE-inhibitory peptides from rohu fish waste. However, UAEE peptides shows better ACEi than MAEE. Keywords: ACE-inhibitory peptide, Alcalase, Degree of hydrolysis, Enzymatic extraction, Peptide yield, Rohu processingwaste