There are also many "cook and hold" oven designs that offer improved preparation consistency and product quality while cooking foods at lower temperatures for increased nutritional value and lower energy consumption. Commercial ovens are usually the largest consumers of cooking energy in the food service kitchen. The oven design and construction quality, as well as fuel choice selection, all influence how much of that energy is discharged to the kitchen as heat. In electric ovens, only 40 to 60% is typically used to cook food, and in gas ovens 10 to 30%. The remainder escapes into the surrounding air of the kitchen, making the environment uncomfortable for the staff, and further taxing the cooling system.
Some of the newer technologies can improve oven performance by increasing speed, energy efficiency and reducing food-portion weight loss, making oven operation much more economical. Of course, these enhancements usually come at an increase in first cost, but may well be very profitable for the food service operator. The purpose of this section is to highlight these oven options and assist the customer trying to decide between them.
There are 11 types of ovens available to the foodservice operator. They are:
Oven cooking is as ancient as civilization, as old as the baking of bread. It is no wonder that oven cooking is still the most common form of food preparation around the world. Consequently, ovens are one of the most widely used types of kitchen equipment. The smallest establishments may have a microwave to heat appetizers or sandwiches and the largest may have a conveyorized bake oven for high volume production.
Ovens are available in a variety of sizes and designs. Some are specifically designed for certain food preparation tasks, while others are meant to serve a diverse range of cooking applications. One of the most recent designs, called a Flash Bake oven, uses a combination of high intensity visible light and radiant heat to increase production speed and improve food preparation quality.
The oven is one of the most common and intuitive cooking technologies since most people are familiar with residential units. First, the oven is preheated to the desired cooking temperature. Next, food to be cooked in the oven is usually placed in containers of metal or glass or on metal pans. Then the food is brought up to a specified temperature for a certain period of time. The speed of this process depends on the size of the food items heated, their geometry, and the rate of acceptable heat transfer to them. For example, thin items like pizza obviously heat much quicker than large items like whole turkeys, and a stuffed turkey will take significantly longer to cook than an unstuffed turkey.
The actual cooking cycle may also require changes in oven temperature over time for a given item cooked, especially where surface browning is desired. For example, a recipe may call for the majority of the baking at 325°F, but with the last few minutes at 425°F.
The most common cooking process design is to surround the item being cooked in hot air. But air is a relatively poor heat transfer agent, especially when compared to the speed with which heat can be transferred by a griddle or by immersion in hot oil. This air heat-transfer process can be sped up by circulating or blowing that air around the food being heated.
Apart from air, some oven designs use high intensity and infrared light, microwave energy or even steam. Each design over time has developed a special niche in the preparation of foods. No one oven design is ideal for all food preparation tasks and many modern ovens incorporate a combination of these technologies.
Electric vs. Gas
There are many factors to consider when selecting an oven: first cost, food preparation productivity, ease of operation and heat generation in the kitchen, as well as the energy source used: electricity or gas. Keep in mind that energy only accounts for 3 to 5 percent of a food service establishment's total costs. So, while one fuel may be less expensive in a BTU to BTU comparison, the best choice in cooking equipment is the one which minimizes total operating costs, not just energy costs. Features that reduce labor costs or result in higher food product yield will nearly always outweigh any energy considerations. Make sure that you include all of these factors in any equipment evaluation.
Let’s take a closer look at the energy use issues, remembering that comparisons should be made on the basis of similar equipment where only the energy input is being changed. Electric ovens generally offer these benefits:
Electric units are more efficient so they add less heat to the kitchen, which ultimately must be removed by the kitchen cooling system. Electric units require less maintenance, require less ventilation, and are more portable. Electric ovens, especially those with electronic controls, deliver more consistent run-quality and require less operational supervision. They are also generally considered to be cleaner and more flexible in their use (especially where maintaining oven humidity levels is important). Flexibility in kitchen design and modification is also achieved because venting may not be necessary. On the other hand, the primary benefit of gas is that it is a less expensive fuel source than electricity.
An oven is composed of a box-like enclosure, heating elements, and controls. The enclosure ranges from a counter-top size, to larger free-standing and floor model units. Ovens normally have a hinged door at the front or side, and adjustable racks or trays to hold food items. Conveyer ovens have openings on two sides. The quality and amount of insulation, plus the presence of an air curtain to retain oven heat when the door is opened, all affect energy efficiency and uniformity of heating.
Deck ovens and conveyer ovens use convection as a heat transfer medium, but are named for the special large heated deck where the food is placed throughout the cooking process. These are commonly used for roasting, baking, and cooking pizza.
Electric heating elements may be at the top, bottom, and/or the sides of the oven depending upon oven design. Gas combustion chambers are also used. Steam is used in special oven designs to shorten cooking times and improve certain food preparation. Yeast-raised breads and pastries are often baked in humidity-controlled proofing ovens. Microwave designs provide heating energy by channeling electromagnetic waves into the oven and rotating the food items to assure uniform heating. Flash Bake ovens use a combination of high intensity light plus infrared radiant energy for extremely rapid heating.
Controls indicate desired oven temperature and certain designs also provide "cook and hold" cycles that greatly extend the time and improve the quality of food service.
The energy efficiency of ovens depends upon how well they are constructed and used. Insulation levels and quality are two of the most significant factors in oven design. Some inexpensive ovens have little-to-no insulation in the oven door. In addition, ovens consume considerable amounts of energy when they are left on, even when no food is being cooked. This is due to losses through the oven walls and air leakage around the door opening. These losses can be a significant component in the operating cost, so remember to turn all oven equipment off, or at least to a lower temperature, during non-operating intervals. This will save energy, reduce cost, and increase oven life. When a food service establishment production requirement does not call for a full sized oven, a half-size oven may operate at much better economies.
Technology Types (Resource)
Gas and electric oven manufacturers are continuing to improve oven insulation and controls, heat transfer effectiveness, and heat recovery technologies. These improvements result in higher efficiency and shorter times for ovens to come up to temperature. Many of these newer designs also maintain a more uniform temperature in the oven zones.
For example, conduction ovens circulate a heat transfer fluid through plates to provide more accurate and uniform heating. Also, Flash Bake technology is making dramatic inroads in the preparation of many trendy foods, such as quesadillas and pizzas.
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