Depending on the breed of pig, they will have 15-16 rib bones. During the butchering process, 2-3 bones are left in the shoulder.
The ribs are then separated into 10-13 bone slabs of baby back ribs and spare ribs.
The remaining rib bones are found in the loin and are referred to as country style ribs. The bones that are left in the shoulder can also sold as country style ribs.
As the name suggests, pork ribs are a cut of meat sourced from a swine/hog/pig.
There are several different variations of pork ribs depending on the section of the rib-cage that they're cut from.
These different ribs cuts all vary in taste as they're sourced from different parts of the animal.
The two main types of pork ribs you'll find are spares and baby backs.
Back ribs or "baby back" ribs or loin back ribs, are sourced from the upper portion of the rib cage, where the ribs and the spine meet.
As the name suggests, loin back ribs contain loin meat and are smaller in comparison to spare ribs.
"Baby back" refers to both their smaller size and location on the hog.
A typical rack of baby back ribs will include 10-13 curved bones (a minimum of 8). With baby back ribs, you should look for even thickness throughout the rack as well as even fat marbling (as apposed to isolated fat pockets).
Baby back ribs contain less meat and fat and are more tender than spare ribs.
When butchered if the rack contains less than 10 ribs, you have what's referred to as a "cheater" rack.
Spare ribs are taken from the bottom of the ribs or the underbelly of the hog - they are separated from the pork belly. These ribs extend around the belly and connect to the sternum.
In general, spare ribs are considered more meaty and less tender. However, they contain more fat which results in added flavor as the fat renders into a gelatin. Due to the more extensive collagen, they will also take longer to smoke than baby back ribs.
Depending on how they're butchered, they will typically contain about 1/4" of meat on the back of the ribs. The more meat left on the ribs means less bacon yield for the butcher.
"St. Louis cut" refers to a style of trimming of spare ribs. They are also called "center cut" ribs because the cut removes the sternum and costal cartilage in order to square the rack.
Traditionally the flap is also removed. However, in a full rack of spare ribs, it's not uncommon to see the flap in-tact. In both cases, I opt to remove the flap.
Country Style Ribs come from the pork loin.
If a butcher is specifically extracting country style ribs from the loin, they're likely removing the first four ribs from the loin that are closest to the shoulder.
The butcher then removes a small piece of blade bone, and then halves the meat. The result are four bone-in country style ribs and four bone-less country-style ribs.
The remaining ribs on the pork loin are then made into a smaller rack of baby back ribs.
Country style ribs come from the same place baby back (loin back) ribs come from. However, in this case, there is a chunk of loin meat.
In an ideal world, every single bone is uniform and the rack is the same size on both ends. The bones also have minimal curvature.
However, as a person who does backyard barbecue, these factors don't matter at all. Uniformity and lack of curvature may appeal to a judge but your Friends and Family only care if they taste good.
In general, when picking ribs at a grocery store, you should look for and avoid the following:
Besides that, there isn't a lot of other considerations apart from the different cuts.
This really comes down to personal preference as I physically can't tell you what you'll like.
For instance, I like baby back ribs more than spare ribs where-as my Father is the complete opposite. My mom isn't a fan of pork ribs and likes beef ribs, and my Dad doesn't care for beef ribs; I like both (however, I tend to lean towards beef).
There are non-taste reasons to like one over the other though. This really boils down to two factors: economics and time.
In general, spare ribs (belly meat) are cheaper - in some cases half the price of back ribs (loin meat); You also get more meat. Loin meat is more desirable and baby back ribs are marketed much better to consumers.
Granted, if you're someone who trims your spare ribs into a St. Louis Cut, the margin of difference shrinks considerably.
I personally think you get more meat with back ribs where-as with spare ribs you get meat and more rendered gelatinous fat.
There is also the factor of time.
In general, back ribs are going to smoke and finish faster than spare ribs. I can smoke a rack of baby backs on my Pit Barrel Cooker in roughly 3 hours. An untrimmed rack of spares can take up to 6 hours (smoking at 250 - 275F).
There are a few different phrases you might see mentioned on different websites or even at your grocery store.
Most, if not all pork ribs come packaged in a vacuum sealed material like Cryovac. When the seal is broken and the ribs are removed from the package, there will be a liquid that remains at the bottom - this liquid is called the "purge."
Meat purge is essentially a combination of water and meat proteins (myoglobin - causes the pink/red hue) that drain from the meat - it is not blood.
This liquid contains the same bacteria that raw meat can, meaning, you should handle the purge with the same care as raw meat.
DO NOT pour the purge into the sink. You should throw away the vacuum sealed material as well as the purge.
Note: Upon breaking the seal, the pork ribs may give off an off smell. This smell is entirely normal as the meat oxygenates. This smell will dissipate after 15-30 mins; If it doesn't, the ribs have likely gone bad.
You'll often find what I call "enhanced" ribs at your supermarket and grocery store. These ribs will usually have a fancy label and say something along the lines of "extra tender."
Essentially, these ribs are injected with a solution of water and other ingredients like salt, phosphates, and flavorings.
The biggest problem with these types of ribs is that most beginners don't know or understand this. They then follow a recipe online that features salt and then apply that to the enhanced ribs - the end result is a very salty rib.
I personally prefer to get my ribs as fresh as possible, ideally never frozen. However, if enhanced ribs are all that's available, they can suffice.
Just be sure that if you're following a recipe or if you're using a commercial rib rub, to avoid using lots of salt, if any.