Refine and update
April 1, 2015
by Laurie Gorton
All bakery technologies are input-driven. Usually, this means designing and engineering the equipment to give it flexibility to handle new products and capacity to meet rising market demand. In the case of fryers, inputs now include ever-stingier emission allowances and tightened energy cost concerns. Even frying fats are in flux.
Market observers such as The NPD Group, Port Washington, NY, report the lines blurring between snacks and meals. Consumer trends clearly favor what is termed “healthy snacks.” While the snacks NPD referenced are usually yogurt and fruit, fried baked goods along with chips and other fried snacks account for the majority of volume.
“Frying processes can give foods a crisp and firm outer coating,” said Joe Mistretta, general manager, FOODesign, a tna company, Wilsonville, OR, “while keeping the inside tender and juicy, a texture combination that appeals to many consumers. It is also possible to develop snacks with intense flavor profiles through frying due to the caramelization of the sugars present in food.”
Certainly, sweet tastes cue the popularity of donuts. NPD, in its National Eating Trends survey, reported that US consumers increased their annual eatings of donuts at home and away from 8.5 times in 2006 to 9.4 times in 2010, raising this bakery item’s “share of mouth” from 7.7% to 8.3% in that period. In 2014, Statistica, a New York City-based statistics portal on the Web, found 61% of US households consuming donuts.
From an operating standpoint, frying technology must position the processor to meet profitability expectations. “For a frying system, the cost drivers are the heating power requirement, oil consumption, downtime for cleaning, oil life time and hourly output,” said Mark Allsopp, export manager, WP Riehle, Aalen, Germany, which manufactures fryers for WP Bakery Group, Shelton, CT.
Advancing the technology is a way of life for fryer manufacturers. David Moline, sales and marketing manager, Moline Machinery LLC, Duluth, MN, noted the company hasn’t rested on its laurels after making significant improvements in its donut fryers with the Libra line introduced a few years ago. “We constantly seek to evolve them with continual improvement,” he said.
Because of the sustainability expectations of customers like Wal-Mart and a rising “green” awareness among consumers, fryers are being engineered to conserve energy. “At the same time, tightening of emissions standards under the Clean Air Act have put further pressure on the snack manufacturing industry to reduce its environmental footprint,” Mr. Mistretta observed.
And let’s not forget acrylamides. With fryers considered a technology “of concern” in forming this harmful substance, equipment manufacturers have applied considerable ingenuity to address the problem.
Fryer engineers have been busy with advances big and small. For example, PPM Technologies, Inc., Newberg, OR, unveiled a continuous kettle chip fryer during SNAXPO at Orlando, FL, in March, and it announced a flow-through popcorn frying system this past fall.
Moline Machinery will debut a new donut fryer in its iba 2015 booth at Munich in September. “The Libra fryer series has been a real winner,” Mr. Moline said. For example, its continuous sediment removal system has become a standard for donut fryers. “Starch and burned particles can build up on the bottom of a fryer,” he explained. “This system automatically removes it on a continual basis.”
Vacuum frying represents a huge step forward in suppressing acrylamides formed when the amino acid asparagine reacts with a saccharide during cooking, frying or baking at high temperatures. It was Florigo’s vacuum technology that attracted tna’s acquisition of the Woerden, The Netherlands-based company in March, explained Michael Green, managing director, tna, Sidney, Australia.
“This technology enables manufacturers to cook their products at lower temperatures, preserving the natural colors, textures and flavors of the product while reducing the formation of acrylamide by up to 95%,” he said. “Vacuum frying is also ideal for products that are high in natural sugar, such as sweet potatoes or even fruits, opening up opportunities for innovative product ideas to cater to the increasing demand for healthier snacks with a difference.”
Heat and Control’s vacuum fryer operates at 10% or less of normal atmospheric pressure so it boils off product moisture at a lower temperature than traditional fryers. “This allows you to fry high-sugar products without browning,” explained Don Giles, director of sales, snack processing equipment systems, for the Haywood, CA-based company. “Oil temperature can be kept below 248°F (120°C), the point at which acrylamide forms.”
The company further adapted its vacuum frying system by unitizing it. In other words, it is built without an external vacuum enclosure. The new design greatly facilitates access for cleaning and maintenance, Mr. Giles noted.
When commercial fryers were first invented, all were batch systems. This cooking style yields a unique crunchy texture, so its products remain popular. Changes to the technology maintain this point of differentiation but add considerably to output volume.
Now able to produce more than 500 lb per hour of finished kettle-style potato chips, Heat and Control batch fryers are being built with frying areas enclosed with a hood for safety to protect oil quality and to reduce energy costs. “The hood retains heat for high energy efficiency, blankets the oil with steam to purge oxygen to prolong oil life, reduces exhaust volume ... and includes a clean-in-place system to reduce sanitation labor,” Mr. Giles said. Continuous removal of fines, an exhaust oil mist eliminator, an automatic chip stirring system and PLC controls are other features.
The new kettle-chip fryer introduced in March by PPM is based on continuous production methods. “The problem with frying chips in batches is that when you want to increase throughput, you have to add more kettles,” explained Nathan Lee, PPM’s vice-president of sales, US and Canada.
“With kettle chip fryers, it’s a matter of balancing cooking temperatures and time duration,” he continued. “By adjusting those, you can adjust the product. The new fryer features multiple heating zone technology that gives much greater control over temperature. We’ve been able to increase the duration in the fryer by adjusting the temperature settings as the chips progress through the fryer.”
Oil inlet ports spaced along the length of the fryer create the multiple temperature zones. “It is a completely different way of managing oil,” Mr. Lee explained. “A programmed temperature profile controls the oil heat, adjusting it up and down through the duration.”
A similar situation pertains to oil-popped ready-to-eat popcorn. It, too, usually employed batch methods, and raising output required adding popping kettles. The new system premiered by PPM feeds unpopped corn into the system at a constant rate. “We applied our star wheel fryer technology, resulting in continuous popcorn preparation,” Mr. Lee explained. Capacity reaches 500 lb per hour.
Many advances in frying equipment involve design, construction and fuels. For example, Moline was able to eliminate welded joints in oil inlet headers and tube bundles by using special tube bending and automated welding processes. “We also improved oil circulation piping in our heat exchangers for greater durability and more sanitary operation,” Mr. Moline noted.
Construction and cleaning
Computer modeling enabled Heat and Control to move to unitized design, according to Mr. Giles. “That maintains precise pan and conveyor integrity, reduces cleaning requirements and improves long-term reliability,” he said.
The company took a modular approach for its new UPC Universal Product Cooker, a continuous frying system. “It allows unlimited adjustment of frying time, temperature and oil flow in each module to produce chips with specific texture, moisture and color qualities,” Mr. Giles said. Users can process traditional potato chips with little or no slice washing and make kettle-style chips, plantain and multi-grain chips, and selected pellet and extruded snacks in one fryer.
Another manufacturer took a close look at product movement within the fryer and made changes. “The new Kemper belt-turning station eliminates the problem incurred on many high-speed lines, where it is very difficult to flip products of different sizes,” said Patricia Kennedy, president of WP Bakery Group. Additionally, an adjustable infeed lets the operator swim or flip products into the frying oil. “Different methods are required for different products, which increases the line’s flexibility,” she said.
Cleaning presents additional challenges. WP Riehle put hydraulic lifting systems on its fryers. “At the touch of an on-screen button, this lifts the complete transport and heating system out of the fryer,” Mr. Allsopp said. “This means access to the oil tub is easy from all sides, and no tools or other equipment are required.” The lift supplements a continuous filter made of 30-µm stainless steel.
Another wrinkle in choosing commercial fryers is meeting environmental restraints and operating them according to the sustainability expectations of customers and consumers. Saving energy costs by selecting efficient heating methods serves the bottom line, too.
Fryers discharge a lot of heat in their exhaust, but much can be used to reduce oil heating costs. Mr. Giles reported that Heat and Control’s booster heater and KleenHeat heat exchanger recover this energy to preheat cooking oil. The system also incinerates exhaust pollutants.
But putting up another exhaust stack is often not possible. “Some bakers are capped out on emission allowances,” Mr. Moline said. “Because bakers have come under pressure to limit stack emissions, they are much more interested in the electric heating option. With an electric fryer, there are no combustion gases.” The company also offers dual-fuel electric/natural gas options.
Energy consumption can be managed from two sides: reducing energy consumed in heating the cooking oil and cutting the amount of energy wasted in heat loss, Ms. Kennedy said. “We only use thermal oil heating or electrical heating, which also give us the possibility to insulate the fryer bath, therefore drastically reducing heat loss,” she explained.
Thermal oil systems circulate a food-grade, noncombustible oil through tubes or flat radiators. The oil, heated in a remote location, never comes into contact with food or frying oils. Thermal oil has a maximum service temperature of about 620°F (325°C) and carries 1,000 times the heat content of an equal volume of air.
Mr. Lee also recommended thermal oil, an indirect heating method. “The big advantage is that you are not applying a flame directly,” he said. Indirect methods reduce the amount of burnt materials accumulating on heating tubes, which decreases heat transfer, causes oil degradation and increases stack emissions.
Fryer design can enhance the green credentials of a system. Mr. Mistretta said that smaller tube configurations help increase heat transfer, enhance system efficiencies up to 84% and reduce overall machine footprint. “Because the amount of tubing also determines the fryer’s overall size, the less tubing required, the smaller the machine’s footprint,” he added. “This also improves oil heating time and decreases energy costs.”
A good control system helps, too. Mr. Mistretta noted an increasing level of automation for frying equipment in recent years. Better controls more tightly monitor temperatures for accurate heat regulation during frying. “This data can then be used to improve production transparency and inform management of changes to improve performance,” he explained. That includes environmental performance.
Application of digital controls not only limits power consumption but also yields better temperature control and, often, less oil absorption and degradation. Mr. Allsopp explained, “This system also allows a lower-volume oil tub, so less oil is needed, and of course, less oil means less power to heat it.”
With snack foods enjoying more popularity than ever and donuts an affordable indulgent treat, their production technology is also advancing to meet challenges posed by the many inputs that drive the frying process. “The snacks market has experienced significant growth over the past few years, and more and more of our customers are looking for quality equipment that can handle greater product volumes,” Mr. Green said.