In ancient Aztec kitchens, a built-in fruit and vegetable storage system called a 'huacalli' was commonly used. A huacalli was a wooden crate or box with slatted sides to allow for air circulation. These crates were often placed in a cool and dry area of the kitchen to keep the produce fresh. The Aztecs also used woven baskets and clay pots to store their fruits and vegetables. The huacalli storage system played a vital role in preserving food in the Aztec civilization, ensuring a stable food supply throughout the year.