Industrial Fryer Must Be Optimized for Superior Product Quality

Today’s food manufacturers compete for consumers with increasingly sophisticated appetites and easy access to abundant product information right at their fingertips.

Global survey results show that people desire natural ingredients while demanding transparency about where food comes from and how it’s made. Also adding complexity is the ongoing fragmentation of tastes in different regions around the world.

For fried food manufacturers in particular, there is increasing pressure to satisfy emerging preferences while continuing to offer a product with appealing flavor, appearance and texture.

Industrial frying equipment plays an important role in achieving this goal by optimizing the factors that impact the final product, namely by limiting the effect of free fatty acids, removing sediments/debris, maintaining a consistent temperature throughout the process, and managing oil turnover.

Free Fatty Acids

The frying process leads to a series of chemical reactions affecting the frying oil, the product and food coatings applied to the product.

One of these reactions, known as hydrolysis, occurs when high temperatures cause moisture within the product to evaporate. Hydrolysis releases free fatty acids (FFAs) and other by-products into the frying oil.

Buildup of FFAs degrade frying oil quality and can produce an “off-flavor” in the product. For this reason, FFA value is one important metric used to assess the quality of frying oil.

Fryer design plays an important role in managing free fatty acids. The ProTherm’s low oil volume, advanced sediment removal, and superior temperature control systems ensure free fatty acids will stay at a low level. This provides your customer with a quality product that consistently achieves the color, flavor and texture they desire.


Besides FFAs, frying oil may also be affected by batter, breadcrumbs or other particulate matter falling off of the product.

Debris removal through filtration is also necessary to preserve oil quality. Advanced industrial frying machines, such as the ProTherm by Nothum Industries, comes with a built-in sediment removal system for preventing FFAs and other debris from exceeding acceptable levels. This system pulls sediments found at the bottom of the fryer to a sludge conveyor, which then extracts and disposes the sediments outside the ProTherm, ultimately leaving your oil clean!


Maintaining the proper temperature throughout the frying process is necessary to ensure a quality end product.

A frying temperature that is too high is one of several factors that can negatively affect the flavor quality of oil. Other factors include FFA content and a high number of fryings.

Advanced frying machines, including the ProTherm, automatically maintain temperature and oil levels while accommodating multiple factors that affect frying temperature.

  • Oil temperature changes temporarily, then recovers, when the product is loaded into the fryer and soaks up heat from the surrounding oil. The manufacturer can minimize fluctuations by including temperature recovery time in heat load calculations.
  • Temperature management must also account for the speed of product throughput and oil turnover rate.
  • Size and texture of the product will also affect the ideal frying temperature. Smaller, thinner pieces of meat or vegetables cook faster than larger, thicker items.

Maintaining a consistent oil temperature has been made considerably easier with the ProTherm. Three independently controlled heating zones ensure proper heating displacement. These zones allow you to heat the infeed (helps control the temperature of cool products entering the fryer), middle (controls balance between infeed and discharge sections), and discharge (continuation of balance) section. With this many heating zones and less oil, there is more square footage of heating surface per gallon of oil within the ProTherm.

Oil Turnover

Fried food absorbs oil, causing oil levels in the fryer to fall. Fresh oil must be added throughout the frying process to maintain proper oil levels.

Oil turnover is calculated as the number of hours required to add the correct amount of makeup oil while frying, and must be carefully controlled to achieve the required product quality.

An oil turnover rate of 7-12 hours is typical for most continuous fryers, but can be longer depending on production rates and the amount of oil required to charge the frying system. Because of these slow turnover rates, excess FFAs degrade the oil which affect the product and oil quality, both in color and taste. This can cause the oil to “smoke” indicating a dangerously reduced “flash point”( the temperature at which oil can combust or catch fire).

The ProTherm continuous fryer has the least frying oil charge in the industry. With oil turnover occurring in less than 4 hours, it is the quickest in the industry! The ProTherm’s automatic oil level system constantly adds fresh oil into the tank. This keeps FFAs low, and allows your oil and product quality to remain high.

Contact Nothum Food Processing Systems to learn more about how the ProTherm helps you deliver the quality fried food products your customers want.

Recent Posts

Need More information?

Learn how you can save time, money and boost product quality and efficiency. Reach out to Nothum Industries today.