Select inedible or damaged apples. Wash them well, clean gently, remove any rotting areas too, but do not remove the seeds. Cut them into small pieces and place them in a container with a wide neck.
The temperature needs to be between 59°F (15°C) - 78.8°F (26°C). Leave it as is for 4-6 weeks without covering the container because fermentation requires oxygen. Stir every day or every 2-3 days. Finally, strain several times through a gauze and drain the fruit. Cover the top of the container with gauze.
Fermentation is complete when the liquid stops giving off gas bubbles and it clears up completely. Filter again and pour the vinegar into dark bottles, cap them. Store in a cool place.