Preparation of high-quality sunflower seed protein with a new chlorogenic acid hydrolase from Aspergillus niger.

OBJECTIVE: To investigate the biochemical and enzymatic properties of chlorogenic acid hydrolase (ChlH) from Aspergillus niger SD14.721 and its applicability in sunflower seed protein processing. RESULTS: The ChlH with two identical subunits (97 kDa) was highly stable. Its optimal temperature and pH were determined as 60 °C and pH 7.0. The Km towards chlorogenic acid (CGA) was 1.85 µM. Based on its N-terminal sequence (AVDSVDAIFA), the purified ChlH appeared to be a new chlorogenic acid hydrolase. When applied in sunflower seed protein extraction, ChlH removed 99.13% of CGA in sunflower seed pastes, thus the colour of sunflower seed protein (SSP) changed from green to grey and its visual acceptance improved. Meanwhile, the solubility, water absorption capacity, and emulsification stability of SSP were increased 48.39%, 59.32% and 22.92%, respectively. CONCLUSIONS: A new ChlH was obtained and its feasibility as a CGA-removal tool to obtain high quality SSP was demonstrated.