Use of a betaine as a foam drainage reducing agent

A process of reducing foam drainage comprising:

• adding a betaine surfactant to a foaming aqueous composition comprising a foaming agent, wherein said betaine surfactant comprises:
• alkyl betaines of following formula (I):
• R1—N+R2R3—CH2—COO− (I)
• alkylamidoalkyl betaines of following formula (II):
• R′1—CO—NH—R4—N+R2R3—CH2—COO− (II)
• and
• mixtures and combinations thereof,
• wherein:
• R1 represents a saturated or unsaturated and linear or branched alkyl group comprising from 16 to 24 carbon atoms,
• R′1 represents a saturated or unsaturated and linear or branched alkyl group comprising from 15 to 22 carbon atoms,
• R4 represents a divalent C1-C4 alkyl group, optionally substituted by a hydroxyl group,
• R2 and R3, which are identical or different, represent a C1-C2 alkyl group, optionally substituted by a hydroxyl group.