Why Are Wet Wipes So Difficult to Preserve? Understanding the Intrinsic Causes

Over the last two decades, significant advances have been made in developing disposable baby wet wipes. Wet wipes consist of two main components: nonwoven fabric and liquid. Being more than 90% water, wet wipes are more susceptible to microbial growth than typical personal care products; hence, high concentrations of preservative compounds are often used to ensure extended protection against contamination. However, there is an obvious tendency to minimize the concentration of irritating actives. Baby wet wipes should contain particularly mild surfactants, well-tolerated preservatives, and a buffer system maintaining the formulation pH at a suitable level for the infant’s skin. Efforts have been centered on removing ingredients with irritation potential, such as phenoxyethanol. In addition, a move towards more natural fabrics is occurring. However, these modifications provoke new challenges in preserving the final products. The nature and composition of the fiber can influence the interactions between the preservative and the wipe, subsequently affecting the performance of the preservative system. In this study, we analyzed the causes of the challenge in preserving wet wipes. We found that fabrics containing natural fibers are the main source of contamination, promoting the generation of biofilms on their surfaces. Moreover, the hydrophilic–lipophilic balance (HLB) was utilized to rationalize the physicochemical interactions between the fabric and the preservatives.