A small portion of food
She choked down a mouthful of food.
He stared at her intently while he chewed a mouthful of food.
She swam as far from the beach as she could, expelled her breath, then drew in a mouthful of water.
Pete sprayed a mouthful of coffee with his snicker.
She downed a mouthful, grimacing at the burn that went down her throat and all the way to her gut.