The combi-oven is the workhorse of the kitchen. It can steam, bake, roast and braise. These are its popular uses and the cooking processes demonstrated in most brochures and by most salespeople.
Yet there are things a combi-oven can do that might not be in the instructions, and there are tricks and tips for getting the most from it, including extra cooking methods, avoiding problems during cooking, and achieving extra energy efficiency, lower maintenance bills and a longer life.
A combi-oven is never flagged up as a fryer, but it can cook food intended for a fryer. Chips and coated food products designed for frying, such as chicken nuggets and fish fingers, will always taste best cooked in a fryer using clean oil. But, aware of the growing call for healthier fried food in sectors such as schools and hospitals, the manufacturers of frozen food products are developing chips and coated products that can be oven-baked successfully.
A combi-oven can dry-fry precooked frozen food using the residual oil on the outside of the food item. This is the theory behind oven chips. The combi-oven can produce a blast of very hot air that browns and crisps the chips. It's not as quick as cooking chips in a fryer, but the oil content will be slightly lower. However, to achieve the best possible crispness and colour, frozen oven chips, not chips intended for frying, must go into the combi. The manufacturing process of the two is slightly different.
With battered or crumbed frozen foods, the same product can be either fried or "air-fried" in a combi-oven.
Grilling is not a cooking function normally associated with a combi-oven, but many foods that are normally grilled can cook perfectly in a combi-oven. Breakfast items such as bacon, sausage, black pudding, hash browns and fried bread will cook quickly and in bulk and have the crispness that would come from frying or grilling through the forced hot air.
This multifunction feature of the combi-oven means many different foods and cooking methods can be put through the oven in any working day. Typically, chickens may be roasted, fish steamed and frozen bakery desserts finished off.
This versatility means there are lots of different flavours and smells pervading the oven cavity. Everything cooked will deposit its own residual taste and the problem of flavour transfer can arise if the oven isn't kept clean.
An extreme example of this is if a batch of roast salmon is followed quickly by sponge puddings, some flavour transfer is likely. Cleaning a combi-oven is quick and easy. Some have a self-clean cycle, but for those without this, it's just a matter of spraying the cavity with a degreaser, allowing it to work on the fat and aromatics, and switching the oven to a short steaming cycle.
Because combi-ovens cook so evenly from the top shelf to the bottom, it's tempting - for reasons including energy efficiency and kitchen efficiency - to load the oven with different foods that need the same cooking mode. Multicooking is a feature of a combi-oven, but it's going on in a closed box and usually with a fan running, and common sense tells you some very strong or very delicate foods are better cooked on their own.
Clean every day
The most important clean cycle is at the end of each cooking shift. Tired chefs may be tempted to leave the cleaning until the next day, but food residue and debris left will harden and build up, becoming increasingly difficult to remove.
Door gaskets need careful cleaning each day. They're built to withstand strong heat and heavy use, but aren't indestructible. The soft and flexible nature of these seals means that, although they keep the cooking atmosphere in, they need careful cleaning to avoid unnecessary damage and premature replacement.
Love those hinges
Door slamming on any piece of kitchen equipment is a common cause of premature breakdown and replacement of door hinges and gasket seals. A head chef should always have an ear for this abuse of combi-ovens and train staff to close doors firmly, but not slam.
Few would buy a new car and ignore professional servicing, yet there are still some kitchens where an investment of more than £6,000 in a combi-oven is not followed by regular servicing. Waiting until something goes wrong before calling in an engineer could result in serious and costly damage to an oven.
The tweaks and adjustments an engineer makes on a routine kitchen visit could save a repair or replacement cost far higher than that regular check-up. Proper servicing is a must if a combi-oven is going to last and perform to its best. Planned, preventative maintenance isn't just a new buzz phrase for looking after kitchen equipment, but a way of heading off more serious problems and having equipment downtime when it suits the kitchen, not in the middle of a busy service.
Any piece of kitchen equipment that takes water from the mains should have a water-treatment system fitted to remove dissolved salts. It's no longer safe to assume that because the kitchen is in an area deemed to have soft (low dissolved salt content) water, that water treatment is an unnecessary expense.
Water companies routinely trunk water from region to region to meet local shortfalls. Water from the mains that has few dissolved salts one month could become hard, with many damaging dissolved salts, the following month.
Dissolved salts cling to the walls of internal metal pipework in a combi-oven as hard limescale and will first constrict, and then possibly block, the flow of water, leading to seriously expensive damage and underperformance.