Popular Mechanics USA - 03.2020 - 04.2020

45 MIN

ENERGY NEEDED

PER LOAF:

280 KJ

EQUIVALENT

TO POWERING

A 100W

LIGHT BULB FOR

HOME OVEN

ENERGY NEEDED

PER LOAF:

6,210 KJ

17 HRS

15 MIN

EQUIVALENT

TO POWERING

A 100W

LIGHT BULB FOR

OHMIC HEATING

VS

Sure, the Ohmic

method saves

energy—but just

exactly how much?

We tapped Sudhir

Sastry, Ph.D.,

professor of food

engineering at the

Ohio State Univer-

sity, to crunch the

numbers on how

much energy Ohmic

heating saves as

opposed to using a

conventional oven

to bake a loaf of

gluten-free bread.

By the

Numbers:

How Ohmic

Heating

Saves

Energy

W

ITH THE RISING POPU-

larity of gluten-free

bread, there is more

demand. The catch? It

takes longer to make. But

scientists from the Insti-

tute of Food Technology

of the University of Natural Resources

and Life Sciences (BOKU) in Vienna,

Austria, may have come up with an

energy-saving fix: using electric shocks

to cook it from the inside out. They

believe a concept called Ohmic heating

could save energy and time during the

manufacturing process, according to a

paper published in the journal Food and

Bioprocess Technology.

Ohmic heating passes an electric cur-

rent through food to generate heat and

cook it. This is possible through what’s

known as Ohm’s Law, where electrical

energy is dissipated into heat

“The heat is generated instanta-

neously within the complete dough,”

Henry Jäger, Ph.D., professor of food

technology at BOKU and paper coau-

thor, said in a press statement in October.

“This is the main advantage of the Ohmic

heating technology. Conventional baking

in the oven requires more time, since the

heat needs to penetrate from the outside

toward the center of the dough.”

Gluten-free bread in general requires

around twice as much water as wheat-

based bread during preparation.

But more water can make the dough

thinner and give it a lower viscosity. Less-

viscous dough often takes longer to bake,

a time suck that can make gluten-free

bread more expensive.

Ohmic heating also provides uni-

form heating to a loaf of bread. That

uniformity, along with the quick-acting

nature of Ohmic heating, could solve

several problems related to gluten-

free bread.

“In order to really benefit from these

advantages and obtain best results, the

optimal process and product character-

istics had to be identified,” says Jäger.

“Achieving such convincing results and

improving the efficiency of the process at

the same time was also surprising for us.”

The Ohmic bread seemed to be supe-

rior in a cook-off against traditional

gluten-free bread—it had 10 to 30 per-

cent more volume, the team reports.

The texture was also better. Crumbs

were “softer and more elastic,” and the

pores “were smaller and more evenly

distributed.”

And, as the scientists theorized,

Ohmic heating saved serious time and

energy—as much as a two-thirds reduc-

tion on both counts.

“At the end, the subsequent appli-

cation of three different process

intensities with different holding times

proved to be the most suitable option,”

Jäger says. “An initial baking step at

two to six kilowatts for 15 seconds fol-

lowed by one kilowatt for 10 seconds and

a final baking at 0.3 kilowatts for five

minutes is the recipe for the successful

production of gluten-free bread using

Ohmic heating.”

Electric Shocks

Might Be the

Secret to Better

Gluten-Free Bread

// BY DAVID GROSSM A N //

8

Food

24 March/April 2020