Fryer design shows wide diversity. This happens because frying donuts is not like making potato chip or popping popcorn. Each product — and each processor — has different criteria.

Donuts, for example, require a shallow kettle depth to facilitate rapid oil turnover, noted David Moline, sales and marketing manager, Moline Machinery.

Regular potato chips benefit from continuous frying with a quick journey through the fryer, thus yielding a light-colored, crispy, finely textured chip, explained Joe Mistretta, general manager, FOODesign. Thicker chips or root vegetables need longer frying times, hence their preparation in batch kettles that output crunchier, darker-looking snacks.

And traditional oil-popped corn is made in batches, but now this old-fashioned product is yielding to continuous processing methods, according to Nathan Lee, vice-president of sales, US and Canada, PPM Technologies.

“The needs of each baker will be different,” Mr. Moline said. This certainly applies to heating options. “For example, our fryers have electric, gas and dual-fuel options, which enables us to respond to differing needs,” he continued. “The baker drives these needs in fryer technology.” His advice applies to snack producers as well.