When it comes to frying donuts and snack foods, advancements in technology now center around providing longer production runs with no degradation in product quality. These enhancements can be used to control oil temperature, evenness of oil temperature and oil quality, which is where filtration plays a key role.

 “For many companies, continuous oil filtration was viewed as ‘nice to have’ and now it’s really become standard,” said David Moline, president, Moline Machinery. “The benefits are just undeniable with their efficiency and ability to run for extended periods of time.”

Nicola Menardo, president, TP Food Group North America, suggested using metallic filters, which activate a self-cleaning cycle when a loss of pressure due to “residue stacking” within the filter itself reaches certain thresholds.

On Tecnofryer’s TEC systems, such filters can perform continuous oil cleaning using a series of metallic surfaces that intercept tiny particles and eliminate them without having to stop the frying process. He added that these filters also eliminate the need for operators to change out paper filters, avoiding close contact with hot oil that poses a potential safety hazard.

Today’s filtration and sanitation systems also focus on minimizing labor and enhancing worker safety, said Matt Asplund, Heat and Control’s application engineering manager. New filtration systems automatically and frequently eject debris from the system before storing it in a safe place.

“For sanitation, this [emphasis] is driving system design to greater automation and reliance on sensors and programs to detect the sanitation system performance rather than the skill and the training of an operator,” he said.

Daniel Luna, director of processing equipment for PPM Technologies, pointed out online oil filtering has improved, but it needs to be tailored to specific production lines and products. Depending on the process, snack makers can use PPM Technologies’ new style drum pre-filters or employ centrifugal or other secondary pressure-style filters.

“Use of positive fines and sediment-removal systems in the fryer can also help in transferring fines from fryer to filters for products that produce heavy fines,” he said.

To recoup oil from some pre-fried snack products, like potato sticks or even French fries, TNA Solutions’ defatter system can recover around 2% of oil relative to the line’s output, said Twan van den Berg, global sales manager, processing, TNA Solutions. Once filtered, this oil passes through a heat exchanger, where it’s reheated and re-injected into the fryer.

“Considering current oil prices, the defatter’s return on investment can be realized within just one year, making it both a sustainable and financially savvy choice,” he said.

To make its fryers easy to clean, Topos Mondial turned to sanitary design with burner tubes separated to provide simple access and a flat bottom kettle for quickly removing fines and other debris.

Reilly Rodriguez, design engineer, Topos Mondial, said the shallow, 20-foot kettle can be drained in under 15 minutes and refilled in 20 minutes, which allows for a complete filtering and recycling of oil daily.

Topos Mondial uses the MFR-730, or melter filter reservoir with a 730-gallon holding tank, that filters, reheats and recycles oil on up to three fryers. He noted that oil quickly drains from the fryer through a set of large particle and dual sediment filters, then to a plate-and-frame filter press for small, biological particulates and both saturated and trans fats.

Rodriguez pointed out Topos Mondial’s 20-foot fryer can make 1,000 dozen donuts an hour with a 110-second fry time. The company also makes kettles up to 32 feet.

“We’ve heavily automated a traditional-style fryer system,” he said. “We made this technology more approachable for entry-level users who are looking to automate.”

Moline Machinery builds fryers in excess of 40 feet and as wide as 50 inches.

“Having segmented heat control in fryers really allows you to fine-tune how your donut is being fried,” Moline said. “We can achieve some slight temperature discrepancies across the length of a fryer, especially the larger fryers.”

Recently, Moline Machinery rolled out its next generation, mid-capacity system that produces up to 18,000 traditional 3-inch ring donuts an hour. It features an all-in-one system for cutting dough and loading the proofer.

“It minimizes the cost of tooling,” he said. “The time it takes to go from Product A to Product B is greatly reduced. Changeover times are less than a minute. It’s ideal for fresh daily delivery bakeries with multiple changeovers every day.”

Van den Berg noted the capacity of the fryer is calculated for such parameters as desired output capacity in tons per hour, gauging the percentage of solids of the raw materials and determining the desired moisture level percentage after frying and drying.

When sizing a new fryer, make sure to determine the required square foot area based on belt loading, fry time and desired throughput, advised Doug Kozenski, sales manager, process prepared, processing sales at Heat and Control.

Producers should then consider the heat load needed for the process and the oil turnover rate, which is defined as the period it takes for fresh oil to totally replenish the full system oil volume during production. 

Ideally, he added, the fryer should be sized to meet the required production rate and run at full capacity. When future growth requires greater capacity, a design layout can be created with minimal modifications.

“If the fryer is oversized and the replenishment takes too long, the oil degradation will result in oil being thrown away prematurely,” Kozenski said. “In addition, the product at the beginning of the day will be different from the product at the end of the day due to the change in oil quality over the production period.”

This article is an excerpt from the May 2024 issue of Baking & Snack. To read the entire feature on Frying, click here.