The Biblical prohibition- Tanning and salting skins:
The principal prohibition-Tanning skin: One who tans skin is [transgressing one of] the principal prohibited actions being that in the [building process of the] Tabernacle they would tan the skins of the techashim and rams.
The secondary prohibition-Salting skin: One who salts the skin is liable for [the prohibition of] tanning being that salting is one of the necessary components in the tanning [of leather].
No Biblical prohibition by foods: However one who salts raw meat, even if he salts it increasingly in order so that it last for a long time and not get spoiled [in the interim], is not liable being that there is no Biblical prohibition of tanning foods.
Summary- The Biblical Prohibition:
The Biblical prohibition applies only to salting and tanning skins, as opposed to meat or foods.