In Hot Oil
Advances in frying technology address a host of issues, including improved energy efficiency, extended oil life and increased throughout.
BakingBusiness.com, September 01, 2010
by Dan Malovany

When consumers began requesting more healthful products, it was only a matter of time before donuts, chips and other fried snacks found themselves in hot oil and in more than how they are cooked. The donut category, in particular, became front and center in the health debate just a few years ago after an onslaught of scientific evidence linked trans fats to heart disease and the obesity epidemic. As sweet goods producers began exploring how to replace partially hydrogenated oils with less stable alternatives, frying equipment manufacturers returned to the drawing table to incorporate new technologies that provided more consistent and gentle heating. Going trans-fat-free proved to be not only an ingredient challenge but a processing one as well.

“Fryer manufacturers have been forced to evaluate the effects of frying with trans fat-free oils,” noted Roger Faw, president and c.e.o. of Belshaw Adamatic Bakery Group, Auburn, WA. “With all that has been learned, there is still more information emerging every day, which forces fryer manufacturers to be diligent in with keeping up with this change, as well as others that are based around more health-conscious eating.”

Because trans fat-free alternatives are more susceptible to breakdown than many partially hydrogenated frying oils, he said, equipment manufacturers working with fried goods producers began testing alternative heating sources to direct-fired gas frying, which can result in quicker degradation of frying oils. According to Mr. Faw, thermal fluid indirect heat sources provide one way to create uniform frying oil temperatures. Such systems can be designed to create a consistent flow of heat across the full width and length of the fryer to maintain product quality and to minimize product reject rates, he added.

THERMAL OIL OPTIONS. To provide advanced frying and filtration options for frying donuts, Belshaw recently entered a joint venture partnership with JBT FoodTech, Sandusky, OH. The partnership combines Belshaw’s engineering experience in the baking industry with JBT’s experience in the snack and protein frying industries, according to Mr. Faw. The new Belshaw-JBT fryer uses JBT’s vertical THERMoFIN fryer combined with a MicroMAX MX hot oil filter for continual removal of starches and baking remnants in frying oil. Belshaw supplies the fryer’s conveyor system for handling various styles of donuts.

“Extending the life of cooking oil is greatly improved by keeping the oil clean,” Mr. Faw said. “This means rapid removal of the sediment and starches in the oil as they occur while continuously filtering." Compared with conventional direct-fired fryers, Mr. Faw noted that the Belshaw-JBT system could provide 15 to 20% in energy savings by combining an external thermal oil heater and the THERMoFIN heat exchanger, which has a compact design to lower frying oil volume. The heat exchanger spans the full frying width, virtually eliminating temperature variation throughout the fryer, he explained. Because the larger heat transfer area significantly reduces heat flux, the fryer provides more gentle heating and extends the life of the oil, especially more sensitive trans fat-free oils.

Additionally, fryer manufacturers such as Belshaw have adopted technology such as shallower kettle designs, continuous filtration systems and internal fryer sediment removal that could extend oil life indefinitely and alleviate equipment-related oil degradation, Mr. Faw said. “To maintain best shortening quality, it is important that the frying oil is turned over during the production time to maximize the constant flow of new shortening into the fryer,” he explained. “In essence, if the fryer is properly cleaned and the oil is property filtered, there should be little need to ever dispose of shortening in the fryer.”

HEALTHY CHALLENGES. When designing a fryer, selecting the optimum conveyance mechanism, fryer size and heat load requirements should be considered, observed Don Giles, director of sales, processing division, at Heat and Control, Inc., Hayward, CA. “Of course, maximum product quality is always the first priority,” he said. “Frying uniformity, oil quality and finished product consistency are keys.”

In addition to addressing product quality issues, Heat and Control developed fryers that use less fuel and oil and are designed to reduce labor for sanitation and maintenance. The company’s MasterTherm fryer features a U-shaped tube thermal fluid heat exchanger that evenly heats oil throughout the fryer. A small volume of thermal fluid rapidly circulates through the heat exchanger to maintain a consistent frying temperature and to adjust quickly to changes in product load.

While salted snack producers have been spared the trans fat conundrum for the most part, their more recent challenges involve creating line extensions with reduced fat and lower sodium levels, Mr. Giles said. Heat and Control has developed a line of continuous centrifuge systems that reduce oil content in snacks by up to 25% and an oil-stripping system that reduces oil content by as much as 33%, he noted.

To add versatility to the production of salted snacks, the company also offers the Universal Product Cooker (UPC) system that can produce not only hard-bite kettle and conventional potato chips but also fried plantains, bananas, cassava, yucca, pellets and tortilla chips with only minimal changes in time and temperature. “Flexible manufacturing technology is important to manufacturers worldwide,” Mr. Giles noted. “The ability to produce batch-style potato chips and regular potato chips on a single system is huge.”

Heat and Control’s UPC system relies on independent fryer modules integrated into a compact system. The design allows snack producers to adjust the frying time, temperature and oil flow in each module to produce chips with specific moisture, texture or color.

In many urban areas, state and federal environmental regulations limit the emission of particulates and nitrogen oxide, prompting fried product manufacturers to take additional steps to comply with air-quality standards. Heat and Control’s KHX KleenHeat pollution control heat exchanger incinerates fryer exhaust without costly afterburner systems and delivers up to 85% thermal efficiency, Mr. Giles said. The company also offers heat recovery systems for fryer exhaust as well as heat exchanger booster heaters and combustion air preheaters.

SIMPLY ELECTRIC. To provide energy efficiency, the LIBRA fryer by Moline Machinery of Duluth, MN, has a low-watt-density, dual-zone electrical heating system that creates even temperatures throughout the fryer. The fryer has a variable-speed surface conveyor drive system that allows frying times from one to six minutes and an electronic torque limiter that helps prevent damage during an overload.

The LIBRA fryer’s kettle design incorporates a bottom sweeper that continually pulls sediment toward the kettle sump basin at the infeed end of the fryer. The sump basin contains an auger that removes sediment from the kettle to the sump drain. Additional filtering of the oil helps improve frying oil quality with less downtime for sanitation. Depending on the system’s size, the fryers can produce anywhere from 1,600 to 4,500 doz donuts an hour, and they can feature independent surface conveyors with a power-driven turner that provides flexibility. Moreover, the system’s remote electrical control panel design keeps fryer controls and other electrical components safely away from the hot oil.

Reimelt Corp., Odessa, FL, provides a variety of frying systems ranging from small systems that can produce 800 to 3,000 pieces per hour to larger industrial systems the can crank out 40,000 pastries per hour. As an alternative to direct-fired heat, Reimelt offers options ranging from electrical heating coils and indirect gas heating to saturated steam heating and thermal oil heating systems with a heat exchangers that can be outfitted with a liquid propane gas, natural gas or even a diesel burner, said Stephen Marquardt, sales and product manager, Reimelt.

In addition to multiple heating options, Reimelt’s fryers are available with a variety of filtering systems to extend the oil’s life. The company’s oil management system, for instance, not only continually filters the oil but it also can store it in a tank beside the fryer after the end of a shift or during preventive maintenance, Mr. Marquardt said.

Reimelt also has developed a downstream injecting system for filling donuts with a variety of jams, cremes and chocolate fillings. In addition to filling long johns and the classic German Berliners, the company worked in conjunction with sweet goods producers to fill tennis ball-sized round donuts with jam and cremes and even produced filled, classic ring donuts, he added.

Though innovation and advances in frying technology, equipment manufacturers allow sweet goods producers to focus on indulgence and stay away from certain health issues that can put them in hot oil. •