Effervescent detergent composition

Detergent compositions having a detersive surfactant system, an effervescent system comprising an acid source comprising an acid or acid-salt blend having the formula ZO2C-(CR5R6)x-C-R1-R2-M-C-R3-R4-(CR7R8)y-CO2Z; wherein xis 0 or 1, y is 0 or 1, R1, R2, R3, R4, R5, R6, R7, R8 and R9 are independently selected from the group consisting of H, OH, branched or linear alkyl hydrocarbon, branched or linear alkenyl hydrocarbon, branched or linear alcohol, branched or linear sulfonate or sulfate salt, branched or linear amine, branched or linear ether, branched or linear carboxylic acid, carboxylate salt substituents having a total of 6 or less total carbon units and mixtures thereof and wherein Z is selected from the group consisting of an alkali metal and hydrogen, with the proviso that on average greater than 1 Z, as measured in the complete acid or acid-salt blend, is hydrogen; and an alkali source are combined such that the acid source and the alkali source are capable of reacting together in the presence of water to form a gas.