,Table of Contents
Lipid Oxidation ........................................................................................................................................ 3
Food Lipids .......................................................................................................................................... 3
Lipid Oxidation and General Mechanisms and Flavour Consequences .............................................. 3
Initiation .......................................................................................................................................... 4
Propagation ..................................................................................................................................... 4
Termination..................................................................................................................................... 5
Decomposition of Hydroperoxides ................................................................................................. 5
Kinetic Aspects ................................................................................................................................ 6
Factors Promoting Lipid Oxidation.................................................................................................. 6
Measurement Methods to Monitor Lipid Oxidation .......................................................................... 8
Lipid oxidation in a multiphase food system (emulsions)............................................................... 8
Factors related to the oil phase ...................................................................................................... 8
Factors related to the aqueous phase ............................................................................................ 9
Factors related to the interface ...................................................................................................... 9
Strategies to prevent lipid oxidation ................................................................................................ 10
Antioxidant Efficiency= matrix-dependent ................................................................................... 10
Antioxidant Synergy ...................................................................................................................... 11
Accelerated Shelf-life Testing ........................................................................................................... 11
Maillard Reaction .................................................................................................................................. 12
Maillard reaction in meat ................................................................................................................. 12
Sugar Reactivity................................................................................................................................. 13
How sugars react w/ the a.a. ........................................................................................................ 13
Maillard Kinetics................................................................................................................................ 16
Zero order kinetics ........................................................................................................................ 16
Determination of Ea ...................................................................................................................... 17
pH Influence on Maillard Kinetics and Flavour Generation .......................................................... 18
Oil Oxidation in Maillard ................................................................................................................... 19
Fermentation ........................................................................................................................................ 20
Types of Fermentation ...................................................................................................................... 20
Pathways ........................................................................................................................................... 20
Malolactic Fermentation............................................................................................................... 21
Citrate Metabolism ....................................................................................................................... 21
Microbial Flavour Compounds .......................................................................................................... 21
Flavour Implications .............................................................................................................................. 23
Proteins ......................................................................................................................................... 23
1
, Fat ................................................................................................................................................. 24
Sugar/ salt ..................................................................................................................................... 24
Physics behind Flavours .................................................................................................................... 25
LogP ............................................................................................................................................... 25
OAV ............................................................................................................................................... 25
Effect of Viscosity .............................................................................................................................. 25
Effect of hardness and chewing pattern ........................................................................................... 26
Effect of contrast in flavour perception ............................................................................................ 26
Impact of cross-modal interactions on flavour perception .............................................................. 27
Composition of Flavourings .............................................................................................................. 27
Importance of Flavour Perception .................................................................................................... 27
Selection of Compounds ................................................................................................................... 28
Legal Aspects..................................................................................................................................... 28
Physical Formats ............................................................................................................................... 29
Liquid ............................................................................................................................................. 29
Dry ................................................................................................................................................. 29
Drying technologies ...................................................................................................................... 29
Taste and Odour Receptors .............................................................................................................. 30
How do we Smell?......................................................................................................................... 30
Odour/ Olfactory Reception ......................................................................................................... 30
Taste Perception ........................................................................................................................... 31
Oral Physiological Processes during Food Consumption .............................................................. 32
Static & Dynamic Sensory Methods for Flavour Assessment ............................................................... 34
Isolation of flavour compounds ........................................................................................................ 35
Machines ....................................................................................................................................... 37
Manipulation and Improvement of Flavour Quality ......................................................................... 38
2
, Lipid Oxidation
Food Lipids
Soluble in organic solvents Non-polar→Triacylglycerols Saturated fa→ No double bonds
Liquid at room T→ Oil (Glycerol backbone connected to 3 Unsaturated fa→ double bonds
Solid at room T→ Fat fatty acids) usually in cis form, may change to
Polar→ Phospholipids (Glycerol trans through hydrogenation.
backbone connected to 2 fa and More sensitive to lipid oxidation.
one phosphate group-lecithin) EPA & DHA→ long
(Amphiphilic=used as emulsifiers) polyunsaturated omega-3 fa
Lipid Function→ precursors of hormones, liposoluble vitamins, pro-inflammatory molecules, energy
storage, structural as cell membranes, texture, surface active properties, flavour, nutritional value,
technological role.
Lipid Oxidation and General Mechanisms and Flavour Consequences
Hydrolysis→ In the presence of water the triglyceride is broken down into its constituents
and is catalysed by alkali, acids, and enzymes (lipases).
Oxidation→ Degradation reaction btw an unsaturated fa and oxygen. Stimulated by light
(photo-oxidation) or enzymes (enzymatic oxidation). Autooxidation though more
problematic in food systems.
Lipid autooxidation is divided into 3 steps;
1/ Initiation in which, light, metals, and reactive oxygen species (ROS) catalyse the formation of an
alkyl radical (L•) by hydrogen abstraction from an unsaturated fa (LH); 2/ Propagation in which the
alkyl radical reacts very quickly with oxygen present to form a peroxyl radical (LOO•). This peroxyl
radical will further react another unsaturated fa (LH) to form a hydroperoxide (primary lipid oxidation)
along with a new alkyl radical (L•) generating a propagation circle of reactions; 3/ Termination during
which non-radical secondary oxidation products are formed (secondary lipid oxidation).
3
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller kaym. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $6.95. You're not tied to anything after your purchase.