Black Streaks in Meat - Food Grinder

Is the securing ring too tight?

If black streaks are appearing on the food, especially meat, it could be because the securing ring is too tight. Black streaks are from the food-grade safe grease that is used inside the attachment. Do not overtighten the securing ring, as that can cause friction and cause black streaks in meat. Use the combination wrench/stomper for securing removal only. 

Was too much force used?

Using excessive force and pushing down on the attachment while grinding can cause friction and cause black streaks to appear. Meat and other foods should be guided gently with the stomper, and allowed to self-feed. 

Never use the stomper to push the food through with force. Instead, use it to gently guide the food into the hopper and allow it to self-feed, to avoid juices backing up into the mixer.