When preparing fruits and vegetables for freezing, which method will best prevent enzymatic browning?

When preparing fruits and vegetables for freezing, which method will best prevent enzymatic browning?

• A. Blanching vegetables before freezing is sufficient.
• B. Treating with ascorbic acid before freezing.
• C. Adding lemon juice after freezing.
• D. Freezing immediately without any treatment.

Answer: (B)

Enzymatic browning happens when damaged tissue is exposed to air and the enzyme polyphenol oxidase oxidizes phenolic compounds to brown pigments. Treating fruits and vegetables with ascorbic acid before freezing provides strong antioxidant protection: it donates electrons to reactive intermediates, preventing their progression to brown pigments, and it also lowers surface pH, which slows PPO activity. This combination helps maintain color during freezing without relying on heat, which can alter texture and flavor. Blanching inactivates enzymes but can soften or alter the produce, making it less ideal for color preservation. Adding lemon juice after freezing is too late to stop browning that begins during processing, and freezing immediately without any treatment won’t prevent browning from occurring.

Enzymatic browning happens when damaged tissue is exposed to air and the enzyme polyphenol oxidase oxidizes phenolic compounds to brown pigments. Treating fruits and vegetables with ascorbic acid before freezing provides strong antioxidant protection: it donates electrons to reactive intermediates, preventing their progression to brown pigments, and it also lowers surface pH, which slows PPO activity. This combination helps maintain color during freezing without relying on heat, which can alter texture and flavor. Blanching inactivates enzymes but can soften or alter the produce, making it less ideal for color preservation. Adding lemon juice after freezing is too late to stop browning that begins during processing, and freezing immediately without any treatment won’t prevent browning from occurring.