Sesame seeds, like many other small seeds, have a relatively high oil content. When heated in a microwave, the oil in sesame seeds can reach high temperatures quickly, leading to a phenomenon known as "thermal runaway." Thermal runaway occurs when a material absorbs microwave energy and heats up faster than it can dissipate that heat, resulting in a rapid increase in temperature.
The rapid heating of sesame seeds in a microwave can cause the plastic container or wrap they are placed in to melt or warp. The microwavable plastic might not be designed to withstand such high temperatures, and as a result, it can deform or melt when exposed to the intense heat generated by the sesame seeds.
On the other hand, some other seeds with lower oil content may not reach such high temperatures during microwave cooking, and thus, they do not have the same potential to cause thermal runaway and melt the microwavable plastic.
It's essential to use microwave-safe containers and follow proper cooking guidelines to prevent such issues. When microwaving foods that contain high-oil content ingredients like sesame seeds, it's advisable to use heat-resistant glass or microwave-safe ceramic containers instead of regular plastic, which is not designed to withstand extreme heat. Always check the manufacturer's guidelines and use appropriate microwave-safe cookware to ensure safe and efficient microwave cooking.