The prized, buttery kernels sold as macadamia nuts come from two Australian trees — Macadamia integrifolia, bearing smooth-shelled nuts, and M. tetraphylla, with rough shells — and they are also traded under the name Queensland nuts. Regarded among the finest gourmet nuts, they are eaten roasted and salted or used in bakery products, ice cream and sugar confectionery. Their high content of monounsaturated fats, especially palmitoleic acid, gives the creamy texture but also makes them prone to oxidative rancidity, so roasting, oxygen-barrier packaging and cool storage are essential. As tree nuts they are major allergens that must be declared; quality grading covers size, colour, oil content and freedom from mould.