Final answer:
Food-grade equipment must be made out of non-toxic, durable, and non-reactive materials such as metal, plastic, glass, or stainless steel to ensure food safety and quality.
Step-by-step explanation:
Equipment must be food-grade and made of materials that are safe for contact with food. While metal, plastic, glass, and stainless steel are all materials commonly used in food handling and processing, the question seems to be asking for a characteristic that applies generally to all food-grade equipment. Therefore, it's not seeking a specific material, but rather that the material be "food-grade." This means it should be non-toxic, durable, and non-reactive so that it does not affect the food's quality or safety. For example, stainless steel is a popular choice for many kitchen utensils and appliances due to its resistance to corrosion and ease of cleaning. Meanwhile, pots might have metal construction but plastic handles to prevent heat transfer and avoid burns during handling.