food analytical methods II Flashcards
What are the key characteristics of chemical methods in food analysis?
Measure a specific property or functional group
Less specific than instrumental methods
More prone to interferences from other food components
Simpler and cost-effective compared to advanced analytical techniques
Useful for stability studies, quality control, and raw material selection
What does the Iodine Value (IV) measure?
Number of unsaturated groups in fats
Used in lipid oxidation studies
What does the TBARS assay measure?
Formation of lipid oxidation products
Measures rancidity in foods
What does the Folin-Ciocalteu (F-C) assay measure?
Total phenolic content
Measures antioxidant levels in foods
What does the Oxygen Radical Absorbance Capacity (ORAC) measure?
Antioxidant activity
Evaluates radical scavenging capacity
What does the Total Oxyradical Scavenging Capacity (TOSC) assay measure?
Ability to neutralize reactive oxygen species (ROS)
Measures antioxidant defense in food and biological systems
What is the purpose of the TOSC assay?
Measures the ability of food compounds (antioxidants) to neutralize reactive oxygen species (ROS)
Used to study oxidative stress in biological tissues and food products
How does the TOSC assay work?
Involves the reaction between peroxyl radicals and α-keto-γ-methiolbutyric acid (KMBA)
KMBA oxidizes to ethylene when exposed to ROS
The production of ethylene is measured using gas chromatography (GC)
What is the formula for calculating TOSC?
TOSC = 100 − (100 × Area under sample curve / Area under control curve)
What are the strengths of the TOSC assay?
Measures total antioxidant capacity
Can be applied to food extracts, tissues, and biological samples
What are the limitations of the TOSC assay?
Does not identify specific antioxidants
Requires gas chromatography (GC) for ethylene detection
What are phenolic compounds?
Plant-based antioxidants found in fruits, vegetables, and grains
Have anti-inflammatory, anti-cancer, and cardioprotective properties
What are the types of phenolic compounds?
Phenolic Acids (C6-C1)
Stilbenes (C6-C2-C6)
Flavonoids (C6-C3-C6)
Xanthones (C6-C1-C6)
What is the purpose of the Folin-Ciocalteu (F-C) assay?
Measures the total phenolic content in food and plant extracts
Commonly used in studies of antioxidants and polyphenols
How does the F-C assay work?
The Folin-Ciocalteu reagent reacts with phenolic compounds, producing a blue color
The intensity of the color is measured at 750 nm using UV-Vis spectroscopy
What are the limitations of the F-C assay?
Not specific to phenolics—other reducing agents can interfere
Results may overestimate total phenolic content
What is the purpose of the ORAC assay?
Measures the antioxidant inhibition of peroxyl radical-induced oxidation
Evaluates the ability of antioxidants to prevent oxidative damage
How does the ORAC assay work?
A fluorescent molecule is exposed to peroxyl radicals
Antioxidants slow down the decay of fluorescence, allowing the calculation of antioxidant capacity
What is the purpose of the TBARS assay?
Measures lipid peroxidation and oxidative rancidity in food
Used in meat, fish, and fried foods to assess spoilage
How does the TBARS assay work?
Lipid oxidation products react with thiobarbituric acid (TBA) to form a pink complex
The intensity of the color is measured at 532 nm using UV-Vis spectroscopy
What are the pros and cons of instrumental methods in food analysis?
Pros: High specificity, accurate
Cons: Expensive, requires advanced training
What are the pros and cons of chemical methods in food analysis?
Pros: Simple, cost-effective
Cons: Less specific, prone to interferences
True or False: TOSC and ORAC assays identify specific antioxidants.
False
Fill in the blank: The F-C assay measures total phenolics but may overestimate due to interference from _______.
non-phenolic compounds
True or False: TBARS is useful for indicating food spoilage and rancidity.
True
