Do non-thermal pretreatments followed by intermediate-wave infrared drying affect toxicity, allergenicity, bioactives, functional groups, and flavor components of Ginkgo biloba seed? A case study

Fresh Ginkgo biloba L. seed (GBS) is allergenic and toxic when consumed even though it is rich in bioactives, thus, limiting its application. In this research, non-thermal pretreatments (ultrasound (US), ultrasound-assisted osmotic (USO), pulsed-vacuum osmotic (PVO), and osmotic (OS)) followed by infrared drying (ID) were applied. A comprehensive analysis of the toxicants (ginkgotoxin and ginkgolic acid), main bioactives (terpene trilactones (ginkgolide A, B, and C), flavonoids (quercetin, isorhamnetin and kaempferol)), antioxidants, and flavor profiles were evaluated. Results revealed that non-thermal pretreatments reduced the ginkgotoxin (3.94–6.24 fold) and ginkgolic acid (6–25 fold) contents to a level which were below the level likely to cause toxicity. Non-thermal pretreated GBS and the control (no pretreatment prior to infrared drying) results showed that the treatments used did not trigger high acrylamide levels and were in a safe range. Combining various pretreatments with ID displayed diverse effects on final products, and the principal component analysis attested to the findings. The control group (no pretreatment) recorded the highest toxic components (ginkgolic acid, ginkgotoxin, and acrylamide), terpene trilactones, and Maillard reaction products compared with various pretreatments. The Fourier transform infrared spectroscopy analysis showed no alteration in the preliminary structure of GBS. Amongst the various pretreatments, PVO had the highest flavor intensities, while the US had the highest total phenolic content and antioxidant activities. Ultrasound treatments (US and USO) had the lowest concentrations for ginkgotoxin, ginkgolic acid and acrylamide, and flavonoids preservation. This shows ultrasound pretreatment before infrared drying can be used during the processing of ginkgo seeds.