Susceptor plates are thin metallic-coated films or boards used in microwave food packaging to concentrate microwave energy in a particular area — typically to brown or crisp the outside of a food that microwaves alone would leave pale and soggy. The metallised layer absorbs microwave energy and converts it to intense local heat, effectively frying the food’s surface. They are the technology behind the crisping sleeves for microwave pizzas, pastries, and popcorn bags. The plates must be engineered so they heat the food without arcing or overheating, and they are single-use components of the packaging. Without susceptors, microwave cooking cannot produce Maillard browning, which is why they matter to product quality.