1. LIPIDS

2. OBJECTIVES
Illustrate the role of lipid stability through a series of designed experiments with oils
Provide a better understanding of lipid oxidation and its physicochemical consequences in foods (organoleptic and physical)
Assess compositional and quality differences between fresh and oxidized lipids
Investigate the role of light and dark on lipid oxidation

3. MATERIAL Oils with varying chemical compositions Pro-oxidants
Antioxidants
Light and Dark storage conditions
Cold vs. ambient vs. hot storage temperature

4. Part I: Designing the experiment
Part II: Analysis
Weigh 0.2g of oil into screw test tubes
Add 1mL of ethanol to dissolve
Add 3mL of TBA, cap tighly and boil (~95°C) for 10min.
Observe the yellow, brown/pink color as reaction of TBA with aldehydes take place
Cool and record absorbance at 530nm
The higher the abs value, the more oxidized the lipid

5. Sensory changes due to lipid oxidation
Report changes in color, odor, appearance and any other aspects (make a table with your observations).
Compare and contrast between control and treatments, use of pro-oxidants, antioxidants, as well as the storage conditions to the control of the oils.
Were the antioxidants capable of slowing the reaction down?
Did the storage conditions affect the oils in a significant way? Why/ why not?

6. Calculating the TBA value
What does this mean???

7. Results: Interpreting
Make a table with the major differences – appearance, color, odor, physical properties, stability and TBARS values – between your oils.
Describe the state of your oils from the literature, and determine if this was responsible for your observed results – In terms of physical and TBARS values
Compare samples with additions of pro-oxidant, and antioxidants, as well as storage conditions. Discuss the differences…

8. EXAMPLE CASE FOR APPNOTE
Your food company wants to introduce a new line of extra virgin olive-oil based salad dressings. However, they have some concerns about the oxidation and are asking for your advice on the topic and your recommendations for the formulation of a prototype dressing.
Be creative!!!

9. Lipid Oxidation – Part Two Analysis
LIPIDS
Lipid Oxidation – Part Two
Analysis

10. Analyzing Lipid Oxidation
Peroxide Value
Hexanal
Thiobarbituric acid Reactive Substances

11. TBARS Assay
Measures byproducts of lipid oxidation by the reaction of TBA and malonaldehyde (A product of lipid oxidation).

12. Part II: Analysis Pipette 0.2mL of oil into screw test tubes
Add 1mL of ethanol to dissolve
Add 3mL of TBA, cap tightly and boil (~95°C) for 10min
Observe the yellow, brown/pink color as reaction of TBA with aldehydes take place
Cool and record absorbance at 530nm
The higher the abs value, the more oxidized the lipid

13. Sensory changes due to lipid oxidation
Report changes in color, odor, appearance and any other aspects (make a table with your observations).
Compare and contrast between control and treatments, use of pro-oxidants, antioxidants, as well as the storage conditions to the control of the oils.
Were the antioxidants capable of slowing the reaction down?
Did the storage conditions affect the oils in a significant way? Why/ why not?