Cracking or cutting bones before making stock increases the surface area exposed to the simmering water, allowing for greater extraction of collagen, marrow, and other flavorful compounds, resulting in a richer and more nutritious stock.
When making stock, the goal is to extract as much flavor and nutrients as possible from the bones. Bones contain collagen, which breaks down into gelatin during simmering, giving the stock a desirable body and mouthfeel. They also contain marrow, a source of rich flavor and nutrients. Cracking or cutting the bones accomplishes several things:
Increased Surface Area: Breaking the bones exposes more of the bone's interior to the hot water. This allows for a more efficient transfer of flavor compounds, collagen, and marrow into the stock.
Marrow Release: Cracking the bones helps release the marrow, which is otherwise trapped inside. Marrow adds a significant depth of flavor and richness to the stock.
Collagen Extraction: Exposing more of the bone matrix allows for better breakdown of collagen into gelatin. Gelatin is what gives a good stock its characteristic jiggle when cooled.
Without cracking or cutting, the extraction process is slower and less complete, resulting in a stock that is less flavorful and less rich in nutrients.
Roasting the bones before simmering them in stock further enhances the flavor. Roasting adds a depth of savory, caramelized notes that significantly improve the overall taste of the stock.