Baking & Snack - July 2022 - 72

OVENS
humidity levels can save energy because
a moist environment holds
more heat than dry air. Products like
hamburger buns retain their softness
with the proper humidity. Middleby
Bakery uses an oxygen displacement
sensor that monitors and adjusts the
amount of oxygen in the oven compared
with the amount of moisture in
the box.
" It's automatically taking those
inputs and controlling the output
fan speed to modulate and hold the
humidity at a constant level, " Mr.
McCally said. " As you add more
product in, you're building up more
moisture so if you want to hold the
humidity at 20%, the fan will speed
up to keep it at 20%. If there is a gap
or the oven becomes less full, the fan
will slow down. "
Cookies, crackers and snacks,
however, tend to benefit from drier
environments. Mr. Zaleski suggested
reducing water in the dough formula,
if possible, to have less moisture
The latest advances
in technology include
emission-free,
hydrogen-fueled
tunnel ovens.
AMF Bakery Systems
limit excess energy consumption. Marie Laisne, product
marketing manager at Mecatherm, said the digital
control evaluates the exact quantity of extracted flow
and allows operators to adjust settings to optimize energy
consumption.
Most ovens also come with modulating burners to
optimize baking conditions and adjust to variations
in product load to avoid unnecessary overheating. For
instance, reducing burner temperatures from 350°C
(660˚F) to 150°C (300˚F) cuts energy loss by 40%, Ms.
Laisne said.
Even the best digital controls cannot compensate for
not-so-good manufacturing practices and lack of maintenance.
Mr. McCally said many bakeries set the exhaust
fan at one speed and run it constantly, even when the
burners are at low fire.
" Many bakers may have problems relighting the burners
consistently, so they'll leave the burners on and waste
fuel, " he observed.
Mr. McCally said bakers also waste energy when they
run their burners with a rich fuel-oxygen mix to keep
them lit. Digital controls can adjust gas-oxygen ratios as
the burners modulate to keep the oven from overheating,
but that only works if maintenance personnel tune
the burners correctly.
For many baked goods, tracking humidity can assist
with oven efficiency and product consistency. Higher
72 Baking & Snack July 2022 / www.bakingbusiness.com
to remove in the oven. Moreover, measure humidity in
each oven zone to determine if the exhaust volume can
be reduced to save energy on reheating the makeup air.
Hot topic of discussion
While DGF ovens remain popular, they tend to require
more upkeep because of the substantial number of burners.
That's why many oven experts, even manufacturers
of DGF ovens, suggest turning to air-impingement ovens
or convection heat to save cold, hard cash.
" The air impingement ovens are hands down much
more efficient in today's environment than direct gasfired
ones, " Mr. Barnes said. " Air-impingement ovens
can change temperature very quickly because you're using
focused convective heating with powerful high-turndown
burners. You're not relying on a hot box. "
Additionally, these older radiant heat systems require
much longer to heat up and cool down. Specifically, he
noted, DGF ovens require 1 to 2 hours to preheat while
air-impingement ones heat up in as short as 30 minutes.
" When you change products and change the bake
profile of the oven, you reduce the latency with convective
heating because it can change air temperatures more
quickly, " Mr. Barnes said. " When you have a production
gap, the typical oven will overheat and result in burnt
edges on one part of the production run and light products
on the other. Newer ovens, especially air-impinge
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