Frying fats represent the cooking or heat transfer medium in which bakery products such as yeast-raised and cake doughnuts are processed.
Frying fats are partially responsible for the unique and characteristic flavor, aroma and texture of fried bakery goods. Different fats confer different flavor and other sensory characteristics and often affect their processing performance.
How does it work?
High-speed bakers with dedicated frying operations rely on heavy duty and flexible shortenings, oils and/or fats for production of a wide variety of snacks and bakery products.
Frying fats must be stable to oxidation, high temperatures and should remain fully functional during their usage. This is why frying fats, oils and shortenings are refined, bleached, deodorized and hydrogenated.
Stability of fats is related to the extent and type of unsaturation of the fatty acids components of fats or oils, and relative reaction rates of unsaturated fatty acids (UFAs) with oxygen.1
Types of frying fats
(liquid or partially liquid at 86°F or 20°C)
(blend of fats and oils)
(solid or partially solid at 86°F or 20°C)
Heavy duty shortening
Fluid (pourable) shortening
Lard (fat from pigs)
Tallow (beef or sheep fat)
The properties and functionality of frying fats are largely influenced by the configuration of fatty acids contained in the triglyceride molecule:
The longer the fatty acid chain, the higher the melting point, and the higher the fat stability to oxidation.
The more saturated fatty acids, the more stable is the fat against oxidation.
Changes in fats during frying
Exposure of fats to high temperatures during frying causes them to degrade with an irreversible aging process. Types of degradation reactions include:2
These reactions produce a variety of physical and chemical changes in the fat, oil or their blends, including increased viscosity (due to polymerization), evolution of volatile compounds (aromas), polarity (total polar materials), increased free fatty acid content (from hydrolysis), color development (darkening), and tendency of the oil to foam (due to gumming caused by polymerization).
Methods for detecting oil/fat oxidation include: iodine value, refractive index, oxidation stability index (OSI) and my others.2,3
Physical and chemical specifications for frying fats include:
Moisture: 0.15% max
Free fatty acids (FFA): 0.10% max. This value helps determine stability. High levels indicate inadequate refining or breakdown.
Melting point: 104–122°F (40–50°C)
Solids fat index (SFI – Proportion of solid to liquid at given temperature):
36% at 50°F (10°C)
18% at 92°F (33°C)
26% at 70°F (21°C)
10% at 104°F (40°C)
23% at 80°F (27°C)
Smoke point: 450°F (232°C)
Peroxide value (milliequivalent/Kg): 1.0 max (measures oil/fat rancidity)
Iodine value: 65–75 (amount of unsaturation or double bonds present in fatty acid chains)