Novel recombinant human serum albumin-SPE systems for ochratoxin A determination – Application in beer analysis

Ochratoxin A (OTA) is a mycotoxin that raises food safety concerns in several products, requiring analytical control. Aiming to develop an alternative to immunoaffinity columns (IACs) for OTA extraction and clean-up, recombinant human serum albumin (rHSA) was explored as an affinity bioreceptor for solid-phase extraction (SPE) applications. rHSA was obtained from Pichia pastoris fused with a C-terminal His6 tag and immobilized on Ni-NTA agarose resin (rHSA-SPE) and Ni-charged magnetic beads (rHSA-MSPE). Developed rHSA-SPE displayed better recoveries than rHSA-MSPE (92-102% vs 62-98%) and effectively captured, cleaned, and pre-concentrated OTA from beer, achieving sensitivity comparable to that of the IAC method. Tests also revealed the stability of rHSA-SPE up to 4 cycles of use. The OTA quantified using rHSA-SPE in commercial beer samples and a certified OTA-beer matrix was consistent with commercial IAC analyses: 0.029/0.022 μg·L -1 (Beer-A), 0.031/0.025 μg·L -1 (Beer-B), 0.015/0.010 μg·L -1 (Beer-C), and 0.329/0.320 μg·L -1 (certified matrix), respectively. • Recombinant HSA captured ochratoxin A (OTA) in column and magnetic SPE systems • Both systems were reusable for at least 4 cycles and stable after 1 month at 4 °C • The column system achieved slightly better OTA recoveries than the magnetic one • Columns efficiently captured, cleaned-up and concentrated OTA from spiked beer • Analytical performance in beer matched that of commercial immunoaffinity columns