Since LDL is sold in a lyophilized form (e.g. from Sigma), lyophilization seems to be a suitable method of preparation. It may be advisable to add a cryoprotectant such as sucrose, if it can be tolerated for your purpose.

Here is an interesting letter to the editor concerning cryoprotection of LDL with sucrose:

https://www.researchgate.net/profile/Michele_Masquelier/publication/14299676_Cryopreserve_LDL_in_the_presence_of_sucrose_to_protect_the_biologic_properties/links/0912f50e3cb6c283ce000000.pdf

Article Cryopreserve LDL in the presence of sucrose to protect the b...