Question
Polyphenol oxidase is responsible for :
The correct answer is
Enzymatic browning
Polyphenol Oxidase Role in Food Reactions
Polyphenol oxidase (PPO) is an enzyme found in plants.
Enzyme Function
PPO catalyzes oxidation reactions. Specifically, it oxidizes phenols to form quinones. These quinones then react further, leading to brown pigments.
Browning Reactions Explained
- Enzymatic browning: This process is directly caused by enzymes like PPO acting on phenolic compounds in the presence of oxygen. It's common in fruits and vegetables when cut or bruised.
- Maillard browning: This occurs between amino acids and reducing sugars when heated, creating complex flavors and brown colors. It does not involve PPO.
- Caramelization: This is the browning of sugars due to heat alone, without amino acids. PPO is not involved.
- Lipid oxidation: This involves the deterioration of fats and oils, leading to rancidity and off-flavors. It's unrelated to PPO's action.
Conclusion
Based on its mechanism, Polyphenol oxidase is directly responsible for Enzymatic browning.
Answer Breakdown:
- Option 1: Maillard browning - Incorrect. Requires amino acids and sugars, not PPO.
- Option 2: Enzymatic browning - Correct. Direct action of PPO on phenols.
- Option 3: Caramelization - Incorrect. Browning of sugars by heat, PPO not involved.
- Option 4: Lipid oxidation - Incorrect. Deals with fats/oils, PPO is involved with phenols.
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Important Questions from Miscellaneous
- Which of the following relationships is/are not true?
(A). Most probable velocity = $\sqrt{\frac{2RT}{M}}$
(B). PV = $\frac{3}{2}kT$
(C). Compressibility factor Z = $\frac{pV}{nRT}$
(D). Average kinetic energy of gas = $\frac{1}{2}kT$
Choose the correct answer from the options given below - Match List-I with List-II
List-I List-II Electronic Configuration First Ionisation energy (kJ mol$^{-1}$) (A). ns$^2$ (I). 2100 (B). ns$^2$np$^1$ (II). 1400 (C). ns$^2$np$^3$ (III). 800 (D). ns$^2$np$^6$ (IV). 900
Choose the correct answer from the options given below: - The shielding constant of a 2p electron (calculated using Slater's rules) is
- Match List-I with List-II
List-I List-II Spectroscopy Property (A). Raman (I). Polarizability (B). FTIR (II). Dipole Moment (C). UV-Visible (III). Absorbance (D). NMR (IV). Spin
Choose the correct answer from the options given below: - The structure of protein comprises of:
(A). Primary structure of protein is associated with amino acids
(B). Secondary structure of protein is associated to peptides
(C). Tertiary structure of protein is associated with polypeptide chains
(D). Quaternary structure of protein is associated with polypeptide chains
Choose the correct answer from the options given below:
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