Food products prepared by deep frying methods are as American as apple pie, the hamburger, pizza and taco.
Their popularity is nationwide and they are served in all types and classes of food-serving establishments.
A reason given for Lhis overwhelming acceptance is that the home is not equipped to properly prepared deep
fat-fried foods. Although deep fat fryers have been manufactured for home consumption for many years, the
resulting food rarely meets the succulent laste standards of commercially prepared products.
In spite of this generally good acceptance by the public, poor preparation of deep-fried edibles
is widespread, so that the end product is soggy and fat-soaked. Basically, two common mistakes or
carelessness contribute to poor quality; (l) frying at the incorrect temperature; (2) frying in stale, "broken down" fat.
Years ago, when deep fat-frying equipment was first introduced, heating conLrol devices were lacking, so that the
cook had to guess at the correct preparation temperature. This resulted in inconsistent and usually
low quality. Actually, the early fryers consisted of nothing more than a vat to hold some crude form
of fat and a basket for the food. The fat, oil or shortening used at that time did not possess Undesirable
characteristics of those products employed today, since the technological aspects of frying were not developed.
Key Factors for Quality Deep-Fried Food
The following are the key factors that contribute to high quality, appetizing and appealing deep-fried foods:
- High quality shortening, fat or oil that withstands high temperature and moisture, has a high smoke point, will not emit unpleasant odors, and will not interfere with the delicate and natural flavors of the food.
- Modern frying equipment that has fast temperature recovery and exact-ing temperature controls.
- Proper frying procedures developed by concise training methods.
- Easily read and posted operating instructions.
- High quality foods, as the initial starting point for a successful program.
Parameters of Deep-Frying Equipment
Deep-frying equipment consists of three basic parts: (1) a deep kettle with sufficient capacity for the fat to
cover the food adequately, so that simultaneous cooking of all surfaces takes place; (2) an accurate thermostatic
device to control the cooking temperature; (3) a sturdy long-handled basket to hold the food; and (4) a heat source
and uniform heat transfer devices. Many refinements and accessories exist that help to increase production and cooking accuracy.
The following list summarizes the essentiaJ factors that should be considered when purchasing deep-frying equipment:
- Rapid heat recovery system. A slow recovery will yield soggy greasy food and a low rate of production.
- Accurate temperature control and a cut-out mechanism to prevent overheating in case of a thermostat failure.
This accessory should be made to cut out at 400°F.
- Rapid and simplified sanitation. Fat wells should be removable so that they can be carried to a sink
for cleaning. The well should be free of crevices and all corners rounded.
- Regardless of the heating source, the heat must be distributed uniformly. Heavy-duty immersion heaters
are recommended for fryers heated by electricity. These heaters should be made to swing in an upright position
for cleaning purposes. They should be self-cleaning when out of the fat.
- All controls should be readily accessible and simple to operate. Controls should be easy to caJibrate.
Automatic timers and signal lights are desirable to eliminate cooking inaccuracies.
- Baskets that are automatically lowered and lifted when the cycle is completed will permit the
cook time to perform other duties or to operate severaJ deep fryers.
- Baskets should be constructed of heavy-duty stainless steel and provided with a long,
sturdy handle as a safety precaution against burning.
- A filtration system, either built into the fryer, or an external accessory unit should be provided.
- Ample "elbow" work space should be provided on each side of the fryer; 2 or 3 ft of counter space is
advisable, to be used for preparation and serving. Locating the fryer at the end of the counter is recommended
so that mobile carts can be used to move the fried food.
- Frying equipment is manufactured in various models and sizes. A choice of floor and counter models is
available. Modular counter types are made so that they fit flush with other cooking equipment of similar overall
dimensions. Movable units should be considered, as these will be able to accommodate production loads in various areas.
- An important provision that deserves mention is the installation of a collecting area or "cold zone", located at
the bottom of the well. This area serves as a collection chamber for charred bits of food and breading materials that
would otherwise float in the fat, causing off-flavors.
- Adequate hooded ventilation is advisable, even though a properly operated fryer will not emit
undesirable fumes or odors. In addition, fryers should not be instaJled near foods that have a
tendency to absorb odors. Coffee under-going brewing is an example since odors from the fryer can be absorbed by the coffee.
Deep Fryer Efficiency and Capacity Ratings
The fryer's capacity or output is rated according to the pounds of product fried in 1 hour.
Most manufacturers base their ratings on the hourly production of raw to finished French fried potatoes (3/8" cut).
There are four basic fryer designs: (1) pre fryers, (2) high production equipment where the food is conveyed through a bed
of shortening (3) nonautomatic fryers ranging in size from a 10 X 10 inches well with a shortening capacity of 15 to 20 lb,
to a 24 X 24 in. well that holds 125 to 135 lb of shortening; (4) automatic units activated by pressing a button that starts
the cooking cycle. The basket is lowered into the well by mechanical means. When
the cycle is completed the basket is raised to drained position.
A fryer of this type measuring 8 X 22 inches. is capable of producing 48 lb of raw to finished
potatoes per hour, or 70 lb of blanched potatoes per hour. High
output models that will prepare 125 lb or more of raw to finished potatoes
per hour are referred to as superpowered frying equipment.
When new frying equipment is installed, tests should be performed for temperature stability
and recovery, rated capacity per hour, and efficiency.
The efficiency rating is determined by measuring the ratio of the fat capacity to the rated hourly production.
For example, if a fryer produces l00 lb per hour of French fried potatoes in 30 lb of fat and another requires 35 lb of fat,
the equipment using the lesser quantity of fat is the more efficient.
Atosa Deep Fryer
In order to achieve a crispy, golden exterior and a deliciously flavored interior for
your deep-fried foods, the Atosa Deep Fryer is the perfect solution. This innovative fryer
fully immerses your french fries, beer-battered shrimp, tempura, or chicken in oil, making
it a more efficient and less labor-intensive alternative to traditional pan frying. It's
important to note that the temperature of the deep fryer will decrease when food is added,
resulting in a recovery time for the fat to return to its optimal frying temperature. If you're
looking for faster recovery time, upgrading to a 50 LB Deep Fryer
75 LB Deep Fryer
may be worth considering. And if you're operating a food truck or don't have access to natural gas, all
Atosa Natural Gas Deep Fryers
come with Propane conversion kits, and there are also
Propane Deep Fryer
options available. As a restaurant, it's essential to have the right equipment to
create the perfect deep-fried dishes.
Continuous Automatic Frying
Designed for volume production, the Fritomat fryer will handle chops, cutlets, liver, sausages, hrunburgers,
deep-fried breaded fish and other meats, potatoes and onions.
The food is fed into the fryer manually. Temperature regulation, conveying, turning over and delivery
of fried pieces are done automatically. Frying time is accurately adjusted. The unit handles up to
1500 pieces per hour or 20 to 30 per minunte.
The food is conveyed through a controlled height of cooking oil which is automatically cleaned
and filtered during tl1e cooking process. The fryer is operated electrically and has four
separate thermostatically controlled heating zones. The finished food is discharged at the lower end of
the machine into a mobile cart.
Determining Size and Number of Units per Installation
The question of the size and number of units needed for an efficient frying operation may be difficult to answer.
There are guidelines that can be followed, e.g., previous experience gained from a similar situation, or from an
established pattern developed from multiunit construction. As a starting point, the following guidelines are suggested:
- A guess may have to be made as to the number of anticipated portions of fried food that
will be served in one hour. If an establishment specializes in fried foods this may be 80% of the food output.
- The size of each portion must be established so that the number of portions that fit into a fryer basket can be
detennined. When ascertaining the basket capacity, keep in mind that only 2/3 of its capacity is used, and preferably
only one-half to avoid overloading. Overloading may affect product uniformity and degree of
- Use as the average preparation time, 5 min for each batch, or I 2 cycles per hr. Multiply tile weight of food
per basket by 12. The resulting answer is the capacity of the fryer required for one hour of continous production.
- If production during short peak demand periods warrants a large fryer, it will be wiser to purchase two units
equaling the capacity of the larger one. Two fryers will furnish versatility so that two food varieties can be
cooked simultaneously, and during low demand periods, one of tllem can be shut down.
If uncertainty prevails, the installation of multiple equipment should be given serious consideration.
In any event, extra space should be aJlowed at tile fryer station so that additional equipment can be installed if needed.
In cases where one fryer is installed, a problem of cooking dissimilar foods at the same time exists. For example,
large food portions may need a longer time cycle. Frying temperatures will also vary according to tile type of food being fried.
The Frying Oil
The use of the most efficient frying medium is as important to quality fried foods as the equipment
used for its preparation. Many products of animal and vegetable origin are marketed. Blends of the
two are also available. In order to arrive at a satisfactory solution as to which brand will produce
quality fried foods, the following characteristics should be evaluated: cost of product, flavor
transfer, smoke point, frying life, and ease of ftltration.
The Smoke Point
The smoke point is the temperature at which a fat heated under specific conditions emits a thin, continuous bluish smoke.
The smoke point of an acceptable frying medium should be as high as possible. A high smoke point usually
indicates prolonged stability. Excessive smoking may be due to deterioration or to the fact that tile product
is not suitable for the equipment.
The following is a list of various frying products and their respective smoke points.
- hydrogenated vegetable oil 440-460 Smoke Point (°F)
- standard vegetable shortening 420-440 Smoke Point (°F)
- cottonseed oil 410-430 Smoke Point (°F)
- corn oil 400-430 Smoke Point (°F)
- lard 340-350 Smoke Point (°F)
- olive oil 300-315 Smoke Point (°F)
Hydrogenated lard is economical and has a smoke point of 380°F. If not overheated, this product is
relatively stable. Vegetable shortenings and oils have the highest smoke point, a long production life,
and a low flavor-transfer factor.
Shortening are more time-consuming to load in the kettle than liquid
frying media. Shortening becomes a solid at room temperalure (70°F), whereas oil is a
liquid under the same conditions. Shortening has to be packed around the heating elements, and heat applied cautiously
to prevent scorching before melting. Filtering must be done at high temperatures or in the liquid state. Oils, on the
other hand, are relatively unstable, may cause smoke or foam sooner than shortenings, and increase cleaning chores.
Opaque liquid all-vegetable deepfrying fat combines the advantages of both shortening and oil, so that it possesses
high stability and is pourable at room temperature.
Quality vs Economy
The saving of a few cents may result in poor, unappealing fried products as opposed to those
that are highly acceptable and of superior quality. The science of frying oils and fats has
progressed significantly over the years and many products arc available today that possess
excellent characteristics. When changes are made from one frying medium to another of a
different character, the results can be detected. Before such changes are contemplated,
tests should be performed to determine the final effect on the taste and flavor properties of the food.
The following is a summary of the desirable characteristics that should be considered when selecting an oil, fat or shortening:
- Bland flavor, so that foreign flavors are not imparted to the food.
- Long frying life, which will result in an economical frying operation.
- Low absorption properties, reducing incidence of greasy food and assuring lower frying costs.
- Ability to produce an appetizing, golden brown, non-greasy, crunchy crust.
- Resistance to smoking.
- Resistance to gumming. A high gum factor will increase cleaning difficulty.
- Resistance to transfer of flavor from one food to another, such as a fish flavor to potatoes.
- Resistance to rancidity under normal care and conditions.
- The ability to fry uniformly under normal conditions of exacting temperature control and even heating.
- Easy digestibility.
Proper and careful handling of the frying medium will assure a more economical operation and products of
higher quality. The frying medium becomes an integral part of the food. During frying the fat is being
replaced by evaporation of surface moisture. Absorption is slowed down by the formation of a
crust; however it continues until the food is removed from the fat. Fat absorption is generally lowest
when surface browning or crusting takes place immediately after the food is placed in the kettle. Slow cooking and
low temperatures cause a high absorption of fat by delaying crust formation. The amount of fat absorbed varies with
the kind and preparation of food being fried, tl1e conditions of the frying fat, and the frying temperature.
Range of Fat Absorption
Absorption is dependent on surface conditions and characteristics of the food, moisture content, and frying
temperature. It can be controlled by maintaining the frying medium in satisfactory condition.
Signs of Deterioration
Often one need do no more ilian step inside the front door of a restaurant to detect signs
of spoiled fat. An irritating, unappealing, rancid odor is proof that either ilie fat must be
changed or ilie fryer's temperature checked. The color of the fat is a useful index of deterioration.
Usually ilie color of a fresh frying medium varies from water-white to pale amber. Dark color is a sign
of deterioration in a fat, and will produce darker fried foods. A color test kit is available containing
five vials, each with a different-shaded liquid. A sample of fat is drawn from the kettle and matched to a
vial of similar color to obtain the score. A final determination is made by means of a taste test.
This test should be performed on a daily basis. lf the flavor is rated unpleasant, acid, burnt or reveals foreign
characteristics, the medium needs changing. Other signs of detection are foaming, a gummy or syrupy
condition, and excessive smoking. If deterioration is abnormally high an attempt should be made to
trace the causes of the rapid breakdown.
Investigation of Excessive Deterioration
The following factors contribute to fat deterioration:
- The main causes of fat spoilage arise from chemical changes induced by oxidation, hydrolysis and polymerization.
Oxidation is the result of a reaction between oxygen and the fat. It begins the moment air comes in contact with the frying
medium and is speeded up as the temperature rises. Hydrolysis is caused by the presence of water in the fat; it splits the
fat molecules, altering the structure of the fat and reducing its usefulness. Polymerization (two or more molecules
joining together to form one large one) results from high temperatures. The formation of gums and resin in the kettle
is a result of polymerization.
- Contamination by foreign materials, such as bread crumbs, potato ends, and other pieces of food debris
contributes to oxidation. It is for this reason that daily straining or filtering is mandatory. Fryers with built-in
collection or cold zones reduce the problem of rapid oxidation from this source. Built-in filtering systems or
external accessory equipment make the job easier. For expediency, the use of cheesecloth or filter paper placed
in a funnel are recommended.
- Contamination by metal such as brass and copper will contribute to fat breakdown; these metals
should not be permitted to come into contact with the kettle.
- The use of detergents to clean the kettle is recommended; however, complete rinsing is necessary
before replenishing the kettle. Soaps and detergents fire injurious to fat.
- Deterioration is also caused by holding the fat at preparation temperatures for prolonged periods
when not in use. During low demand or slack periods lhe tempernture should be reduced to 200° F.
- A continuously operating fryer will keep the fat in good condition. Fryers that are infrequently used contribute
to a faster rate of fat deterioration. Fat is continually removed from tl1e kettle by absorption. To maintain
a constant quantity of frying fat in the kettle, fresh fat must be added. The rate at which this is done
is designated as "fat-turnover". A satisfactory daily measure of fat turnover is 15 to 20% of the fat content. Rapid fat
turnover keeps the fry ing fat in good condition through frequent replenishment. In a well-balanced
frying operation with adequate turnover, it is seldom necessary to discard any used frying fat.
Consumer Preference for Frying Fats
In February, 1971, a research report was published showing the results of a nine-month study of
consumer preferences for food fried in various types of cooking fats. This work was performed
at the School of Hotel Administration, Cornell University.
Four commercial types of cooking fat were employed in this study: an opaque liquid all-vegetable product; a winterized cottonseed oil;
a hydrogenated solid all-vegetable fat; and an animal-vegetable solid fat. The results of these extensive studies revealed a difference in the fat performance of
the various products tested under similar conditions. The opaque liquid all-vegetable frying fat
was the most efficient, with equal or superior food acceptance ratings over an extended period. The
consumer was able to recognize differences between French fried potatoes cooked in the various fats.
The consumers choice was indicated by ranking the test products singly or in pairs.
Deep Frying Procedures
Deep-frying procedures are simple, especially when using automatic equipment. However, simplicity in itself
will not produce quality food unless a rigid schedule of operating and sanitation procedures are followed. The following
procedural pointers should be incorporated into a well-defined operational program:
- Determine if the cooking time and temperature settings recommended by the manufacturer are adequate.
Periodic checks should be made of the time and temperature factors to determine if changes have occurred
because of a malfunction of the timer and thermostat. Use an accurate thermometer to check cooking
temperatures and a stop-watch to test the timer. Determine tl1e temperature drop when the kettle is
loaded; a sharp decrease in temperature may causrature to reach its cooking setting. Reduce the food load in the basket
until the recovery period is reduced, to assure optimum performance. Hang a time-temperature chart in
front of the equipment for reference.
- Before putting food in the fry kettle, wipe off or shake all excess moisture, crumbs and loose breading.
All portions or pieces of food should be about the same size. Food having a· high moisture content, like fish,
oysters or U,awed items, should be drained carefully before frying.
- Always keep the fat content of the kettle at the proper indicated level. Add additional fat when level drops.
- Fill basket only half full of food and never exceed two-thirds of the capacity. Never overload as a
means of increasing production. Overloading will delay heat recovery and will also result in excessive
absorption due to the inability of the heating equipment to maintain proper frying temperatures. A good
ratio to maintain is I lb of raw food to each 6 lb of frying fat.
- When frying frozen foods, do not thaw, but place in kettle directly from the freezer.
Below-counter freezers are ideal for temporary storage. These units should have removable
stainless steel drawers. Counter fryers can be installed directly over the freezer box.
- Do not salt food over the kettle or use excess salt. Addition of salt to the frying oil will
tend to shorten its usefulness and retard browning.
- Turn kettle off or set at 200° F during slow periods. Most fryers will recover rapidly.
- Allow the finished fried food to drain. Where excess fat is observed, blot food on absorbent paper.
- lf charred pieces of food are floating on the surface of the fat, gather them together with a
long-handle mesh filter and remove.
- For foods that are breaded on the premises, the following procedures are suggested. Start breading
when food reaches room temperature. Dipping and breading should be done by using both hands-one hand for
dipping, the other for breading. Heavily breaded foods require additional frying time. Certain wet or moist foods,
such as oysters, scallops, fish or fillets, should be allowed to "set" or "rest" for several minutes before
frying, so that the breading and dip mixture can seal. If necessary , redip and bread. When frying breaded
foods, place them flat in the basket without touching.
- To ensure continuous high-quality production, taste the fat for signs of deterioration. This should
be done at the beginning of each shift or at the start of the day's business.
Selected Examples of Frying Procedures
The time cycle will change with the initial temperature of the food, moisture content, condition of the fat,
efficiency and condition of the frying equipment, size of the portion, and the amount of food loaded in the basket.
Many gourmet, specialty and nationality semiprepared frozen foods are being marketed. A number of these products
are made for finishing in a deep fryer. This trend is an outgrowth of the increasing use of convenience foods.
Examples are breast of chicken Kiev, stuffed potato balls, and breaded Italian style eggplant.
Potatoes are marketed in four forms: blanched and frozen, blanched and refrigerated, potato powder,
and fresh raw. The most popular are the blanched and frozen. This popularity stems from a more uniform product
and high-quality yield.
To ensure a quality product, potatoes should be kept frozen at all times. The amount of "frost" on
their surface is an indication of the product's temperature. If blanched and frozen potatoes are
permitted to thaw, they will absorb twice the normal amount of fat. This will produce a greasy, limp and
unappetizing finished product.
Blanched and refrigerated varieties do not present preparation problems. However, they do not have the
eye appeal or crisp texture of frozen potatoes. Blanching can be accomplished in the fryer at 300° F for 3 to 5 min.
After draining and cooling they are placed in a covered plastic or waxed container and stored in a refrigerator
for about 72 hr. Never allow sliced potatoes to touch metal or remain uncovered, as they will turn dark.
The raw to fresh type result in an excellent product during certain periods of the year. Because of changes
within the potato as it ages, it is not possible to produce a uniformly high-quality finished product 12 months of the year.
Seafoods are best prepared from the frozen state. Most seafoods are breaded before f1ying. The product
can be purchased with or without breading. A clisadvan lagc of breading on the premises is the appearance of
un-even brown or dark spots on the fried fish. This problem is attributed to a moist breading product.
If the breading is not dry, the fish must be rebreadcd to obtain a uniform surface color.
Onion rings are a popular deep-fried item. These products are available fully breaded and frozen. The
extruded onion ring is gaining in popularity. These rings are formed by an extrusion process and are uniformly
sized and firm. Because of the firmness, their shape is retained, whereas most other onion rings are fragile and
may fall apart. For optimum results, onion rings must be fried in the frozen state and served hot.
Breading on the premises is time-consuming and the resulting product does not usually measure up to the final
quality standards of the pre-breaded variety. If breading is to be performed on location, freshly sliced sweet
Spanish onions should be used. These are dipped in bread flour and then in to an egg-milk batter
(6 medium size eggs for l pt milk) and finally into a commercial breader or cracker meal. Depending
on the amount of coating desired, the last two steps can be repeated; however, allow a
few minutes "set-time" between applications.
Broilers weighing from 1 to 2 lb should be cut into several pieces.
Poultry of this size will yield about 4 to 6 uniform pieces. Roll the chicken in
seasoned flour (salt and pepper added). Chicken frying is performed at lower temperatures
than for most other foods. Temperature should be 325° F and fried for l2 to l5 minutes.
High-quality fried products are contingent on proper and complete sanitation of the deep fryer equipment.
Procedures recommended for a daily and for a weekly program follow:
Daily Fryer Maintenance
- After power is turned off and the fry basket removed, raise heating elements to half position
to drain, then move them to the upper limit or until they lock in place.
- Remove fat well (for safety, wear heat-retardant gloves or use a pot holder) and filter the fat.
If fryer contains filtering device, turn it on.
- Wash baskets and tank and rinse. Remove all traces of soap or detergent. Allow to dry.
After drying, replace tank and refill with the filtered fat. Replenish with fresh fat to proper level.
Weekly Fryer Maintenance
- Drain and clean kettle.
- Replace kettle and fill with water mixed wiili a fry-kettle cleaning agent (2 oz to I gal water).
- Lower the heating elements into ilie cleaning solution and turn on the power until ilie liquid comes to a boil.
- Turn off U1e power and allow to stand for JO min or overnight.
- Rinse and dry the heating elements, fry tank and baskets. Apply a final rinse of a vinegar water solution
to "sweeten" the metal surfaces.
- After drying, replace the filtered fat and replenish to the proper level.
- Turn the unit on and check the thermostat and temperature with a hand thermometer.
Cause of Common Frying Problems
Fat Darkens Excessively and Prematurely:
- use of inferior or wrong type of fat;
- faulty thermostat;
- inadequate filtering of fat
- improper and inadequate cleaning of equipment
- hot spots in kettle;
- food may be improperly prepared, to much moisture
- foreign matter entenng the fat.
- inadequate fltering of tl1e fat;
- improperly prepared food;
- use of wrong type of fat, smoking point too low.
- overheating of the fat;
- faulty thermostat;
- inadequate cleaning;
- hot spots in kettle;
- poor ventilation.
Poor Browning and Undercooked Food:
- excessive foam development;
- overloading kettle;
- faulty thermostat;
- frying temperature too low;
- improper preparation of food;
- poor or slow recovery of the temperature;
- check cooking procedures for time and temperature.
Excessive and Persistent Foaming:
- use of wrong type of fat;
- overheating or faulty thermostat;
- hot spots in kettle;
- Fat being held at frying temperatures for long periods without cooking;
- improper sanitation and failure to remove fum from equipment before replenishing;
- overfilling the kettle with fat;
- kettle too large for the operation;
- salt in fat;
- poor or no filtering;
- frying temperature too low;
- overloading kettle;
- frying in foaming fat;
- improper preparation of food;
- improper draining of food after frying
- slow temperature recovery.
Obnoxious Odors from Kettle:
- use of inferior fat;
- use of deteriorated or spoiled fat;
- use of poor quality food;
- excessive debris ( crumbs, charred food) in fryer;
- foreign matter in kettle.
Objectionable Flavor of Fried Foods:
- use of inferior fat, deteriorated or spoiled fat;
- foreign matter in kettle;
- use of poor quality food;
- inadequate Iii tration and presence of debris in fat;
- excessive fat absorption;
- poor turnover.