The sugar in a poaching syrup penetrates the fruit and keeps it firm during and after cooking.
Sugar also slows the cooking process, so the fruit takes longer to cook and absorbs more flavor.
Lay parchment on top of the fruit as it simmers in syrup. This helps the fruit cook more evenly. Poaching syrups are usually made with granulated sugar and water, but brown sugar, honey, and maple syrup, used in roughly the same proportions, add rich flavors and a deeper caramel color. Try fruit juice or wine for part or all of the liquid. Wines with high acid or tannin are best mixed with an equal amount of water.