I am trying to extract DNA from bean seeds for pathogen detection but I am having problems with the quality of the DNA obtained probably due to the high concentration of inhibitors on bean seeds. 260/230 ratio is low (0.2 to 0.7) and no good band visualized with agarose gel at 0,8%. Bean seeds were grounded in a ball mill /MM 200, Retsch, Haan, Germany for 30 s at 30 Hz. From 150 mg to 10 mg of the fine powder obtained were attempted with 3 different protocols:

Literature research mentions the preparation of samples using liquid nitrogen, I tried freeze-drying the seeds because I do not have liquid nitrogen and still got the same results. Does someone have a suggestion or tip on how to solve this problem?

Thanks