The shape of a steam jacketed kettle is spherical, and this increases the surface area for the steam to disperse inside for evenly cooked food. Steam is one of the best sources of heat to cook food with; this is because steam allows the cooked vegetables to retain its fiber, texture, color, and flavor. Steam cooked vegetables will also retain the water-soluble vitamins like B and C besides preserving the potassium, zinc, and phosphorus content which are essential for the body to function optimally.
The steam cookers are extremely safe to use, as they operate at a pressure of not more than 50 psi; most machines and boilers generate the steam which is circulated inside for fast and evenly cooked food. Alternatively, many steam cookers, kettles, and pots use an internal steam generator, which can be either gas-fired or an electrical heating component. The best factor of cooking with steam is the eliminated risk of scorching or burning the food, which is possible with other methods of cooking.