Protecting New White Tile Grout From Mould and Staining in Shower Stall

[mike41124]

Hi folks
I'm seeking advice on protecting white grout in the shower stall from becoming black.
I do clean as best I can after every use with a cloth and once a week with a cleaning product. I fear this is not totally adequate. So, if possible and effective, I would like to coat or cover the grout with something.
In a local DIY place i saw the silcone anti-muffa (anti-mould, I live in Italy) substances. Would any of these satisfactorily protect the grout? Or can something else be recommended.? (generic products please, as certain brands might not be available here in Italy)
Thank you,
Mike

[lets have a look]

No they won't, silicone on tap of grout looks horrible, open the window after showering/bath and the black mould won't form and wash the tiles once a week.