Optimization of fermentation parameters with magnetically immobilized Bacillus natto on Ginkgo seeds and evaluation of bioactivity and safety

摘要

In this study, magnetically immobilized BadUus natto fermentation approach was developed on Ginkgo seeds. Some parameters potentially influencing the fibrinolytic activity of fermented Ginkgo seeds were systematically Investigated and optimized by Plackett-Burman and Box-Behnken designs, and the optimum fermentation conditions obtained were 60 mesh particle size, 150 ipm stirring rate, fermentation pH 6.5, 43.0 h fermentation time, 36.4 C temperature, 16.4 mL/g llquld-solld ratio and 1.0 g/g beads-solld ratio. After fermentation, the satisfactory fibrinolytic activity of Ginkgo seeds was 3175 ± 43 lU/g. The total flavonoid contents were reachd to 2.6 ± 0.2 mg rutin equlvalent/g Ginkgo seeds, 2.5-fold higher than that of unfermented Ginkgo seed. Hie contents of Ginkgolic acids dropped to 2.2 ± 0.4 lig/g Ginkgo seeds, which were 8.3-fold lower than untieatd control. Meanwhile, the reusability of magnetically immobilized microorganisms was tested and the activity of magnetically immobilized microorganisms was above 80% after 8 cycles. We concluded that this magnedcaBy immobilized fermentation approach on Ginkgo seeds could be efHdently applied for food and Industrial production, and the fermented Ginkgo seeds increased the fibrinolytic activity, flavonoid content and improved the food safety.