Did my Bolivian torch cacti get too cold? What else could be wrong?

[emax]

Hi everyone I just registered cause I'm a newbie when it comes to cacti.

I got those a few days ago, they were sent by mail in a box, it's pretty cold here (around 0 degree Celsius, so almost freezing). Maybe that was a bad time to order them? They were on the way with the delivery company for around 2 days.

They developed a weird colour since they arrived. In the beginning they had a nice juicy green, but now turned into yellow/brown/grey ish.

Also I'm not sure about the soil, is this just the small hairs from the roots, or is it mold?

What should I do?
I re-potted two of them. They seem ok, but same as the other one that is still in the small pot. I put some tee tree oil on the soil plus some liverworts extract in case it's mold.

The big pots I put two of them in, are filled with this stone stuff and fertilized cactus soil. Both made for cacti and succulents.

I keep them in my livingroom at around 25 degree Celsius and under indirect natural light from the windows.

Any suggestions how to improve their health?

Thanks a lot!

[Jangaudi]

Always good to check this guide, and consider a different soil for your cactus. Also, if it's wintertime where you are, then the cactus will be dormant, so 25 °C sounds too hot, and watering is not a good idea during winterrest either. So I would let it rest for now, until spring Discoloration could be due to increased light.
https://www.cactiguide.com/forum/viewto ... 25&t=40641

[teo]

From the last image I would suspect possible root mealies

[esp_imaging]

Where are you, and where where they sent from? It looks to me like they may have got frozen solid in transit, in which case I'd expect they are dead.
Are they squashy to the touch, or firm?

I agree, they also look like they have root mealy bugs.

[emax]

Hi, thanks a lot for your answers and advice! I will keep an eye on that soil and maybe continue the tea tree oil, as it could also help against possible mealy bugs? I didn't see any bugs though, I looked very closely, nothing is moving there, no yellowish or blueish discolourations anywhere in the pot or the soil either.
I hope they recover from the cold shipping. It was shipped between Germany and Austria. 2 days in the cold. I keep them in my livingroom at about 25° Celsius. I also have no colder room for their winter hibernation.
And yes luckily they are still firm, not getting squishy or soft or so. Today another one got a more healthy color already. But one seems very bad and turned even darker brownish so I guess that one will die. But the others seem to recover.