Biochemical Test Results for Peanuts

Steps:

• Identify the four standard food tests: Benedict's for reducing sugars, Biuret for proteins, emulsion for lipids, iodine for starch.
• Apply to peanuts: low sugars yield yellow in Benedict's; proteins yield purple in Biuret; lipids yield white emulsion; no starch keeps iodine brown.
• Match colors to choice A: yellow (sugars), purple (proteins), white (lipids), brown (starch).
• Eliminate mismatches in other choices based on incorrect color outcomes.

Why A is correct:

• Matches standard results: peanuts show low reducing sugars (yellow precipitate per Benedict's scale), proteins (lilac-purple via Biuret reaction), lipids (milky white emulsion), and absent starch (brown iodine solution).

Why the others are wrong:

• B: Red indicates high sugars (incorrect for low in peanuts); blue suggests starch presence (false positive).
• C: Black implies strong starch reaction (peanuts lack starch); clear for lipids misses emulsion.
• D: Blue for sugars means negative (but peanuts show slight yellow); blue for proteins mismatches purple.

Final answer: A