Black neck in tomato ketchup is due to the formation of:

Correct option is A

Black neck is a common defect observed in tomato ketchup, especially during storage, where the neck portion of the bottle turns black.
Key Points:
· Cause:
· It occurs due to the formation of ferric tennate.
· Mechanism:
· When iron (from metallic containers, lids, or processing equipment) reacts with the tannins and organic acids present in tomato pulp, it leads to the formation of ferric tennate, a black-colored compound.
· This reaction particularly happens when acidic tomato products are in prolonged contact with iron surfaces.
· Prevention:
· Use of food-grade, non-reactive containers like glass, stainless steel, or coated tins.
· Proper lining of metal containers to prevent iron exposure to the product.
· Immediate filling and sealing practices.
Other Options Explained:
· (b) Potassium citrate:
· A salt formed from citric acid and potassium, not involved in black neck formation.
· (c) Ferric sulphate:
· A different iron compound; not responsible for black neck in ketchup.
· (d) Sodium acetate:
· A salt of acetic acid and sodium; unrelated to black neck formation.