Frying Flashcards
What is continuous frying?
Complete or par-fried cooking
What is batch frying?
Conventional (open air)
Kettle (crisps)
Air frying
How does frying work?
Heat and mass transfer and chemical transformations
What needs to be considered during frying?
Sensory parameters
Abuse and testing oils
Oil filtration
What is hydrolysis when frying?
Replacement of water with oil
How does water effect frying?
Attacks ester link in triacylglycerols and produces di and monoacylglycerols and free fatty acids
How do free fatty acids effect oil?
Produce off flavours
Why does hydrolysis occur more in oil with short, unsaturated fatty acids?
They are more soluble in water
What is the initiation process of thermal oxidation?
Hydrogen in fatty acids is removed and lipid alkyl radicals are produced which react with each other to form dimers and polymers
What is the propagation process in thermal oxidation?
Peroxy radicals gain a hydrogen atom from an oil molecule forming hydroperoxide and more radicals (free radical chain reaction)
What is the termination process of thermal oxidation?
Formation of nonradical volatile and non-volatile compounds
What is polymerization of oils?
Formation of cyclic compounds depending on temperature and unsaturation of the oil
What are the volatile compounds produced by oils?
Aldehydes- lipid oxidation
Hydrocarbons (ketones, carboxylic acid)- provide deep-fried flavour
Furans, pyrazines and pyridines (small amounts)
How does water escape when fried?
Moves towards crust and evaporates
What are the toxic compounds produced during frying?
Cyclic fatty acid monomers
Acrylamide
Heterocyclic amines
Trans fats
