Extraction, catalytic study and milk-clotting properties of proteases from Brassica oleracea
Author(s)
Date Issued
2024
Type
article
Volume
60
Journal
Abstract
Proteases were extracted and biochemically characterized from different Brassica oleracea varieties (B. oleracea var. palmifolia (black cabbage, BC), B. oleracea var. sabellica (curly kale, K), and B. oleracea var. botrytis (white cauliflower, WC)). Calf rennet (CR) and Cynara cardunculus crude extracts (CC) were used as reference samples. The catalytic study used two different substrates: the synthetic peptide Bz-Phe-Val-Arg-pNA (BPVA-pNA), which contains para-nitroaniline (pNA), and azocasein (AzC) as a macromolecular substrate. The effect of temperature and pH on the proteolytic activity were also evaluated. Brassica proteases were further proposed as milk coagulants, and their coagulating efficiencies were evaluated. Bovine casein was incubated with the plant extracts, and the relative breakdown products were observed through electrophoresis. BC, K, and WC contain proteases which hydrolyze the macromolecular substrate (AzC) and synthetic peptides with Arg in P-1 (BPVA-pNA). Therefore, among the three B. oleracea varieties and control extracts, K leaf extracts displayed greater catalytic efficiency against AzC. Brassica extracts showed a lesser milk clotting index but visible milk curd formation. More importantly, the protease activities of BC and K extracts exhibited great catalytic activity over a broad range of pH (3.6–9.0) and temperatures (40–70 °C) using AzC as a substrate. Current pH and thermal tolerance results indicate that B. oleracea var. palmifolia and B. oleracea var. sabellica proteases could have broad applications in food technology. Many plant resources, which could represent potential sources of efficient proteases, are still unexploited.