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The following information is provided
courtesy of The Catering Equipment Suppliers Association.
Understanding Combi Ovens
A combi-oven
combines several cooking functions in one piece of kitchen
equipment and the shortening of the description “combination” is
how a combi-oven gets its name. The combi-oven uses dry heat -
either still or fan-driven - and steam, which is injected into
the oven when the food being cooked needs it. An alternative
name for the oven is the combi-steamer.
The
combi-oven is the most versatile piece of equipment any
professional kitchen can have. These are just some of the
examples of its benefits:
Meat
– Up to
a third of the weight of a piece of meat can be lost during dry
roasting through loss of the water content of the meat. Having
gentle steam in the oven during roasting both minimises weight
loss and produces a more tender joint.
Fish
– steaming is an ideal cooking medium for this delicate product.
Vegetables
– By cooking in steam instead of boiling water, vegetables keep
more of their nutritional value and natural colour.
Baking
– by operating as a fan-driven convection oven, baked goods are
evenly and crisply cooked. A slight injection of steam can also
enhance some baked foods such as bread.
Regeneration
– Food which has been pre-cooked and correctly chilled prior to
service can be rapidly brought up to serving temperature,
avoiding the need to hold food hot for long periods which leads
to flavour loss and drying out. Combi-ovens are ideal for busy
banqueting operations and can handle both ready-plated meals and
multi-portion containers.
What is needed
in the kitchen to install a combi-oven?
A water supply and
energy supply. Combi-ovens will run off electric, mains gas and
LPG.
How to
calculate the size of combi-oven needed
This is a job an oven
manufacturer will arrange for you. The size of combi-oven needed
is calculated by the amount and types of food to be cooked.
A combi-oven
is not just for big food operations
Combi-ovens come in a
range of sizes and all manufacturers build ovens for the small
independent caterer as well as the very high volume outlets
Technical question to ask before making a choice of combi-oven
·
What
are the performance and cost implications resulting from steam
coming from a water boiler or by spraying water onto heated
elements in the oven?
·
Why
is it necessary to fit a water filtration system to the oven to
remove dissolved salts in the water and prevent scaling?
·
Is
there a high pre-heat function to enable fast heat recovery when
cold food is put into the oven?
·
How
easy the oven cavity and the door seals are to clean and what
self-cleaning features the oven has.
·
What
are the programming features, how easy are they for staff to
understand and do they meet my kitchen needs? Is there a
self-diagnostic facility to warn me should something go wrong?
·
Is
there a food core temperature probe, rapid cool-down feature or
a reversible fan for even heat distribution?
Look
after it!
The
combi-oven is the workhorse of the kitchen and one of the most
versatile items of prime cooking equipment any kitchen can have.
It can steam, bake, roast and “dry-fry” chips, breaded and
battered frozen products using the residual fat in the
coating.
This
multi-function feature of the combi-oven means many different
foods and cooking methods may be put through the combi oven in
any one working day. Typically, chickens may be roasted, fish
steamed and frozen bakery goods finished off. That versatility
means there are lots of different flavours and smells occurring
in the combi-oven. Everything cooked will deposit its own
residual taste in the oven which brings up “Look After It” rule
No. 1 – keep the oven clean to avoid flavour transfer.
This is
important where strongly-flavoured foods such as chicken or fish
have been cooked and then vegetables are to be regenerated or
patisserie and desserts cooked. Many combi-ovens have a
push-button clean cycle which will wash the oven cavity and take
away any food residue so a delicately flavoured food following
on tastes of its ingredients sand not what was previously
cooked. Where a high production kitchen has a bank of
combi-ovens, if there is not an in-built self-clean cycle, it is
possible to get mobile cleaning systems which can be wheeled to
each oven in turn.
The most
important clean cycle is the one at the end of each cooking
shift. Food residue and debris left will harden and build up.
Door gaskets
are built to withstand high heat and heavy use, but they are not
indestructible. The soft and flexible nature of these seals mean
that while they keep the cooking atmosphere in; they do need
care to avoid unnecessary damage and subsequent replacement.
Door slamming on any piece of kitchen equipment is a common
cause of premature service need and replacement cost. A kitchen
manager should always have an ear for this abuse of combi-ovens
and train staff to close doors firmly, but not slam.
Door seals
can also suffer from a build-up of food debris. The folds in the
door gasket which give the close seal will inevitably attract
food debris. The manual or automatic clean cycle will clean the
oven cavity, but a manual inspection and clean with a grease
detergent and clean cloth will bring long life to door seals.
High-fat
foods such as chickens can deposit large amounts of fat in the
oven. Combi –ovens have different ways of dealing with this.
Some have fat drains where the chicken – or any residual grease
– drains through a pipe in the bottom of the oven into a
collection bucket.
Some have
just internal collection depositories or there may not be any
facility to collect excess cooking grease.
Where a trap
system is built into the combi-oven, the route the fat travels
through must be cleaned at the end of every working day to
prevent a build-up of fat becoming a hygiene and oven drainage
problem.
The
combination of different cooking systems in a combi-oven gives
versatility, but it also combines water, heat, electricity and
computer circuitry in one cooking machine. None of those
elements sit easily together and a bad reaction between two of
those factors can be a cause of operational problems that need
an unplanned visit of a service engineer.
Which
highlights the most important point of looking after a
combi-oven. A regular service contract is essential. This is
preventative maintenance which can spot problems in a combi-oven
before they become expensive.
Water
treatment for combi-ovens is very important, check the index for
a separate section on this.
In brief
Do
Fit a water
treatment system
Check door seals weekly
Clean daily
Don’t
Cook
strongly flavoured foods with delicate foods
Allow fats to carbonise in the cavity
Overload
Leave food debris trapped in door seals
Neglect to clean fat drains
Slam doors
Trap probes in doors
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