Zest adds concentrated citrus flavor without the bitter white pith found in the peel, resulting in a brighter, cleaner taste in custards and puddings.
When making custards or puddings, the goal is to infuse a delicate citrus flavor without introducing any unwanted bitterness. The zest, which is the outermost colored layer of citrus fruit, contains the essential oils responsible for the characteristic citrus aroma and taste. These oils are highly concentrated in the zest.
The white pith, located beneath the zest, is bitter and can negatively impact the overall flavor profile of the custard or pudding. Using whole peel, which includes the pith, would introduce this bitterness, overpowering the other delicate flavors. Zest, on the other hand, provides a pure, clean citrus flavor without the bitterness.
Furthermore, the fine texture of zest allows it to disperse evenly throughout the custard or pudding mixture, ensuring a consistent flavor in every bite. Whole peel, even when finely chopped, may not distribute as uniformly.
Use a microplane zester for the finest zest possible. This will help the zest incorporate seamlessly into your custard or pudding and release its flavor more effectively. Avoid grating too deeply, as you want to avoid including any of the bitter white pith.