Step 1: Understanding the Problem:
The question asks to identify the specific lipid oxidation product measured by the Thiobarbituric Acid (TBA) assay to evaluate rancidity in meat and food products.
Step 2: Detailed Explanation:
• Lipid Oxidation Process: Lipids in meat products (especially polyunsaturated fatty acids) undergo autoxidation over time. This process occurs in three stages: initiation, propagation (forming primary oxidation products like hydroperoxides), and termination.
• Secondary Oxidation Products: Hydroperoxides are unstable and decompose into various secondary oxidation products, including aldehydes, ketones, and short-chain fatty acids.
• Malonaldehyde (Malondialdehyde - MDA): MDA is a major three-carbon secondary dialdehyde produced during the decomposition of lipid peroxides.
• TBA Reaction Principle: In the TBA assay, two molecules of 2-thiobarbituric acid react with one molecule of malonaldehyde under acidic, high-temperature conditions. This reaction forms a pink-colored chromogen with an absorption maximum at $532\text{ nm}$. The intensity of this color is directly proportional to the level of secondary lipid oxidation (rancidity) in the meat.
• Other Options: Free fatty acids indicate hydrolytic rancidity (measured by Acid Value). Peroxides are primary oxidation products (measured by Peroxide Value).
Step 3: Final Answer:
The TBA test measures the concentration of the secondary lipid oxidation product malonaldehyde, corresponding to option (B).