Question

Sequentially arrange the steps involved in the enzymatic browning of fruits and vegetables: A. Formation of brown melanin compound through condensation and oxidation B. Nucleophilic reaction-O-quinones react with amino acid C. Tissue damages/ruptures cell component, releases PPOs-phenolic substrate D. Oxidation to quinones-PPO oxidizes diphenol to O-quinones E. O2 exposure activate PPO which catalyzes monophenol to diphenol

• A. C, D, E, B, A
• B. C, B, D, E, A
• C. C, A, D, B, E
• D. C, E, D, B, A

Hint:

Understanding this sequence can help in managing food browning by controlling factors such as oxygen exposure, temperature, and pH levels.

Answer 1

The Correct Option is D

Step 1: Concept
The enzymatic browning process involves a series of biochemical reactions triggered by polyphenol oxidase (PPO). These reactions lead to the formation of brown pigments, primarily melanin-like compounds, which are responsible for the browning observed in fruits and vegetables when exposed to oxygen.

Step 2: Meaning
Understanding the sequence of events that occur during enzymatic browning helps in managing food quality and shelf life by either promoting or preventing this process.

Step 3: Analysis
1. C - Tissue damage ruptures cells, releasing phenolic substrates and PPOs (Polyphenol Oxidases). 2. E - Oxygen activation of PPO catalyzes monophenols to O-quinones. 3. D - Oxidation of diphenols by PPO results in the formation of O-quinones. 4. B - Nucleophilic reaction between O-quinones and amino acids leads to the formation of melanin-like compounds. 5. A - Final step where these quinones undergo further condensation and oxidation, forming brown pigments.

Step 4: Conclusion
The correct sequence aligns with the biochemical steps involved in enzymatic browning: tissue damage releasing substrates and PPOs, followed by oxygen activation of PPO to form O-quinones, then the formation of melanin-like compounds through quinone reactions, and finally the condensation and oxidation to produce brown pigments. Final Answer: (D)