The main ingredient in jelly is fruit juice, which is combined with sugar and pectin to create the gel-like consistency. Pectin, a natural thickening agent found in fruits, plays a crucial role in helping the mixture set properly. Jelly can be made from a wide variety of fruits, including strawberries, grapes, apples, and raspberries. The juice is often extracted from the fruit, filtered, and then cooked with sugar and pectin until it reaches the desired consistency. This combination gives jelly its sweet flavor and smooth texture, making it a popular spread for breads and pastries.