spoiled, sour, moldy
餲 centers on food that has gone bad: spoiled, sour, or moldy. The meanings all describe the state of food that is no longer fresh or edible.
餲 combines 飠 (food) with 曷, which likely contributes the sound. The character specifically refers to food that has spoiled or turned sour.
The food radical 飠 beside 曷 looks like a container of food left out too long. Imagine a pot of food that has been forgotten and now smells sour and moldy.
For エイ, picture an egg (エイ sounds like 'A') that has spoiled and turned sour. The rotten egg smell cues エイ while the food radical reminds you it's about spoiled food.