Optimization of Lactobacillus plantarum Fermentation Medium Incorporated with the Pseudostellaria heterophylla and Investigation of the Antioxidant Activity of the Generated Fermentation Broth
Objective:To develop an optimal fermentation medium incorporated with the medicine Pseudostellaria heterophylla for Lactiplantibacillus plantarum and provide a scientific basis for the utilization of P.heterophylla resources and the development of its related products.Methods:With the cell density as the response value,Plackett-Burman design was used to identify the culture medium compositions that had significant effects on the growth of L.plantarum.The central points for Box-Behnken design were determined using orthogonal experiments and the Box-Behnken design of response surface methodology was used to obtain the optimal medium compositions.The antioxidant activity of culture broths(dried powder)was evaluated by DPPH free radical scavenging rate,ABTS+free radical scavenging rate,and FRAP method.Results:The water extract of P.heterophylla was an excellent ingredient for L.plantarum fermentation.The optimal medium was comprised of 29.7 g·L-1 maltose,27.5 g·L-1 yeast extract,7.6 g·L-1 water extract of P.heterophylla,and 0.5 g·L-1 MgSO4.With the optimized medium in the fermentation,the cell density reached 1.11×108 CFU·mL-1.The fermentation broth of the optimal medium had a higher DPPH free radical scavenging rate than that of unfermented medium(blank control),but lower than that of fermented MRS medium(reference control).The ABTS+free radical scavenging rate and FRAP value were both higher than those of the latter two controls.Conclusion:The water extract of P.heterophylla is an excellent medium composition for L.plantarum fermentation,and its addition can improve the cell density.The antioxidant activity of the optimal medium was improved by L.plantarum fermentation.
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