Lecture 12 Flashcards
What nutrients do fats have?
9kcal/g Omega 6 (linoleic) and 3 (linolenic) Antioxidants (EC) Fat soluble vits Hormones
What do fats help with in the body?
Brian
Nerve
Retinal Cells
What are the 2 kinds of fats?
Liquid
Solid (Plastic)
What are plastic fats?
Solid at room temp and can be moulded or shaped like butter
How does hydrogenation occur?
Add H to create trans double bonds instead of cis double bonds
What happens to the stabilities of fats when there are more double bonds?
The more unsaturated and the more double bonds there are they are less stab le
Are mono/poly fats solid or liquid at room temp?
Liquid at room temp
How do you determine the degree of unsaturation?
Iodine test
- Saturated fat will take up no iodine
- Unsaturated will take up more
What are the 2 properties of fats?
Fat crystals and polymorphism
What are fat crystals and polymorphism ?
The fatty acids attract via van der Waal forces to bond and form crystals as it cools
- Symmectrical and similar carbon length will for more readily
- Affect melting point and properties in food
What are the 3 forms of fats when cooling?
Alpha
Beta prime
Beta
What is the difference between Heterogenous and Homogeneous fatty acids?
Heterogenous- Beta prime (milk fat)
-all 3 fatty acids can be different
Homogeneous- Beta (lard)
-all 3 fatty acids are the same
What form out of the 3 fats are more stable, smooth and porous?
Beta prime is more stable than alpha
Beta Prime creates a more smooth and creamy product
Beta is more porous and better for frying and making crusts
For the melting point what influences the strength of bonding forces between the fatty acids?
Type of fat
Form
Length of the fatty acids
Which fats have a lower melting point?
Asymmetrical fats
Cis and unsaturated fats
-due to the kink in these structures so it isn’t as packed together and requires less energy to melt
What happens when there is more attraction between the fat molecules?
Its easier for it to crystallize and the higher the melting point because it will take more energy to Melt the crystals
Which fats have higher melting point?
Trans and saturated fats
What is the solid fat content?
Measures the melting range
-useful in a commercial setting to give you the idea of the range for the specific fat
What is the smoke point?
Temp at which smoke comes from the fat surface when heated
-indicates thermal stability when in contact with air
What is the smoke point dependent on?
the ease of hydrolysis to glycerol and % of free glycerol
What is acrolein?
- Excessive heating and smoke
- Free glycerol decomposes to water and acrolein
- Mucous membrane irritant
What are the oils with the highest smoke points?
Corn
Canola
Soy
Peanut Oil
What is the flash point?
Heating the oil after the smoke point
-temperature of volatiles being ignited, cannot sustain combustion
What is the fire point?
Temperature of volatiles sustaining combustion
-if it happens dont throw water on it
What decreases the fire and flash point?
More double bonds
What is plasticity?
Fat does not undergo permanent change in shape until a stress of force that has been applied
- solid fats
- beta crystals are smooth and creamy
- composed of liquid and crystal portions allows flexibility
What are the functional aspects of fat?
Texture Tenderness Emulsification Heat transfer Control of Crystallization Moistness
How is texture a functional aspect?
Flakey textture for pie crusts-shortening
Fried Foods are crisp
Viscosity, creaminess- milk fats
How is tenderness a functional aspect?
Fats interfere with development of gluten and shorten the gluten
How is heat transfer a functional aspect?
Heated to higher temperatures above boiling
-flavour and colour
How is control of crystallization a functional aspect?
Stable and small crystals
-chocolate and ice cream
How is moisture a functional aspect?
Contributes to a sensation of moistness
Why do we process/refine the oil?
- To get the Ideal oil that has Oxidative stability, functionality and nutrition
- Remove undesirable colour flavour, quality and safety
- Remove FFA, phospholipids, carbs, protein, water, pigment, volatiles and contaminants
What are the steps to processing and resining of fats?
Settling Degumming Neutralization Bleaching Winterization Deodorization
What happens in the settling step?
Separates oil from water, protein and phospholipids and carbs
What happens in the Degumming step?
Removes gums and phospholipids from crude oil
-if not removed they cause a darker colour
What happens in the Neutralization step?
Remove FFA with NaOH and residual phospholipids to improve colour
What happens in the Bleaching step?
Remove colour (chlorophyll), trace metals and oxidation products
What happens in the winterization step?
improves clarity, and crystals are filtered
- Cloudiness results because some of the triglycerides in the oil have higher melting points than the other molecules in the picture which leads to crystallization and can become more solid in the fridge.
- Doesn’t impact the functionality of the oil
What is the process of hydrogenation?
Adding hydrogen to points of unsaturation in fatty acids to become saturated
H2 bubbled through liquid oil in presence of nickel catalyst which speeds up the rxn
-change liquid oil into solids or plastics
What is part hydrogenation?
Causes trans fatty acids
-not permitted
Why is hydrogenation used for?
Shortenings for desirable shortening power
What is interesterification?
Fatty acid addition or rearrangement on glycerol backbone by chemical or enzymatic process creating a “new” triglyceride
Bonds broken on FA and re-esterified on same glycerol (intra) or different glycerol (inter)
Does not change the FA but rather rearranges them
What is fractionation?
Separate triglycerides by difference in melting point, solubility and volatility
-process is used in processing pal and kernel oils
Why are additives added to fats?
Protect quality and prolong storage
What kind of additives are added to fats?
Antioxidants- reduces oxidation (BHA, BHT) helps prolong shelf life
Lecithin- emulsifyer
Citric acid- metal chelating agent to inhibit oxidative rancidity
Polyglycerol esters- modify and inhibit crystallization
What is rendering?
Extracting animal fat-process to help extract animal fat. Melting down and reprocessing the meat
- byproduct of meat processing
- process uses heat or steam to remove fat
What is tallow?
Rendering og cattle and sheep
- deodorized or undeodorized for flavour
- biofuels, soap /detergent are also called inedible tallow
Whats the difference between deodorized or undeodorized rendering?
Deodorized- doesn’t alter taste of food
Undeodorized- will alter flavour
-removes volatile compounds using steam
What is lard?
Fat rendered from pig
- fat depends on pig diet
- used in pie crusts
- produces white grease
What is white grease?
Form of lard thats a specific grade and an be used int he making of animal foods
What are the sources of marine oils and what are their nutrients?
Fish, fish liver, krill, squid, seal, algae
Long polyunsaturated FAs Vit A&D Less Stable ans susceptible to oxidation EPA, DHA, ARA Sustainable
What is milk fat?
Naturally occurring trans fats that are 5% of the fats
What re the 4 fat crystals of milk fat?
Alpha
Beta
Beta Prime 1
Beta Prime 2
What is the destabilization/coalescence of milk fat?
Irreversible increase in fat globule size
- lose individual identity
- This is important for fat emulsions at this stage
What is partial coalescence of milk fat?
Fat globules held together by fat crystals and liquid fat as long as structure is maintained
What is flocculation of milk fat?
reversible clustering fat globules, no loss of identity, can be re dispersed
- not a permanent state
- happened when individual fat cells are clustered together
- once fat globules melt they uncoalesce
What is the butter phase of milk fat?
Phase inversion, hardness of butter depends on saturated fatty acid content, crystal size seasonality
- break oil and water emulsion via agitation
- crystalization is temperature dependent and smaller crystals will influence hardness
What is cocoa butter?
Cocoa bean undergoes fermentation, roasting, drying and develops the flavour
- nib contains 53% cocoa butter
- traps flavour aroma compounds only released when melted
What is the melting point of cocoa butter?
Similar to mouth temp
-narrow range of 31-34C
How many forma can cocoa butter be crystallized into?
6 forms with different melting points
What form of cocoa butter is ideal for chocolate making?
Beta V crystals
-are glossy, uniform and snaps
What is chocolate?
Nibs are ground= suspension of cocoa solids in cocoa butter=chocolate liquor or mass
What is conching of chocolate?
Stirring of cocoa mass at controlled temp for 4hr-3days
-Aeration develops flavour (drive off moisture and some volatile acids)
What is tempering of chocolate?
Control of temp to produce stable V fat crystals
-gloss, texture, stability
What happens when you have unstable crystals when making chocolate?
Gives a white or grey appearance
-this is called a bloom and has no effect on taste and food safety
Is which chocolate chocolate?
It is chocolate because it does have cocoa butter in it, they just dont add the coco liquor or solids that give it the flavour or colour
What is Hydrolytic rancidity?
Hydrolyzing fatty acids from glycerol backbone, produces FFA
Involves water, heat and light
Lipase helps break apart the fatty acids
What is oxidative rancidity?
Unpleasant odour and taste
Occurs with O2, heat light and metals (Fe, Cu)
Unsaturated fats are more susceptible
