Signal-enhanced SERS-sensors of CAR-PLS and GA-PLS coupled AgNPs for ochratoxin A and aflatoxin B1 detection

•AgNPs@pH-11 gave the highest and most stable SERS enhancement factor.•AgNPs @pH-11 was used to fabricate SERS-nanosensor with low LODs.•The SERS-nanosensor detected ochratoxin and aflatoxin in cocoa beans at pg/mL level.•The sensor coupled to chemometric algorithms rapidly detected toxins in cocoa beans. Ochratoxin-A (OTA) and aflatoxin-B1 (AFT-B1) pose debilitating health threats to consumers and therefore require rapid monitoring with sensors. This work synthesized silver nanoparticles (AgNPs) within (4 ≤ pH ≤ 11) ± 0.2 to attain different enhancement-factors (EF). AgNP@pH-11 which gave the highest SERS-EF (1.45 × 108) was selected to fabricate SERS-sensor; and coupled to two chemometric algorithms for the prediction of OTA and AFT-B1 in prepared standard solutions (SS) and spiked-cocoa-beans samples (SCBS). The LOD for OTA (2.63 pg/mL) and AFT-B1 (4.15 pg/mL) in the SCBS were lower compared with 0.002 µg/mL. The built-models recorded residual-predictive-deviations above 3. Obtained recovery rates of 96–110%; and the low coefficients of variation (2.12–8.07%) realized for both toxins suggest the predicted results are reproducible. The SERS-sensor holds promise for the rapid quantification of OTA and AFT-B1 at pg/mL level in cocoa beans to enable safety assurance in the cocoa beans industry.