Interaction between potassium sorbate, oil and tween 20: Its effect on the growth and inhibition of Z bailii in model salad dressings

Abstract

The effect of the interaction between potassium sorbate (KS), oil and Tween® 20 on the growth and inhibition of Z bailii in model salad dressings was studied. Z. bailii grew in emulsions containing 110 and 230 g/kg of oil and the addition of 0.5 g/kg of KS inhibited growth. When the oil content was raised to 460 g/kg, a steep death rate curve was observed and the effect of KS addition was hidden by the inhibitory action of the high oil level. Tween® 20 action depended on oil level: for emulsions containing 110 or 230 g/kg, a depression in the activity of KS was observed. This behavior was attributed to the decrease in the free form of the preservative due to the partition between surfactant micelles and the water. In contrast, when the oil content was 460 g/kg, KS activity was enhanced in spite of the decrease in the amount of its free form. These results highlight the importance of considering ingredient interactions when evaluating shelf‐life.