Zylc is a traditional meat jelly from the northern part of Poland known as Pomerania. The area borders Baltic sea which is known for short waves, cold water and strong winds. Traditional Zylc was a meat jelly made from pork legs that agreed very well with vodka or beer. Native people living in the area known as Kaszuby started to incorporate pork heads and any meat cuts that remained after the pig’s slaughter.
Nowadays, it is difficult to buy a pork head, which is usually sold split into halves, clean and ready for cooking, so most people will substitute head with pork shoulder or upper part of front leg known as picnic. The meat requirement for a head cheese or meat jelly is basically the same as the manufacturing process remains almost the same. If stuffed into pork stomach or a large diameter synthetic casing the product becomes a head cheese, but if it is left to cool in a bowl it becomes a meat jelly. In both cases we need meat with a lot of connective tissue because such meat contains a lot of collagen that will first melt and then cool down forming a jelly. The jelly will connect all parts nicely together.
One could use a commercial gelatin which will bind any type of meat, with connective tissue or not, however the taste and flavor of the finished product will be different. A meat jelly made with mixed with water gelatin powder has a neutral flavor, but the liquid that remains after cooking meats and vegetables is a wonderfully tasting meat stock, so the traditionally made meat jelly exhibits a superior taste and flavor.
Kaszuby introduced some notable differences, firstly, they grind all cooked materials through a fine plate, secondly, they add enough vinegar so the product develops a slightly sourly flavor. Most people eat head cheese or meat jelly with lemon juice, vinegar or pickled cucumber anyhow, so adding vinegar works very well. An American headcheese known as Souse also contains a noticeable amount of vinegar.