Effect of mixing method on resulting thickness of infant formula

Previous research shows that factors such as time, temperature, nutritional make-up of a liquid, and type of thickening agent can significantly alter the resulting thickness of liquids. This study sought to determine the effect of three distinct mixing methods on the resulting thickness of ready to feed infant formulas mixed to Mildly and Moderately Thick (International Dysphagia Diet Standardization Initiative [IDDSI] Levels 2 and 3) with three different thickening agents. Eight commercially available infant formulas were mixed with three different thickening agents by three different mixing methods. The IDDSI Syringe Flow Test was used to categorize the thickened formulas. Chi square analyses were completed to determine the impact of mixing method on the thickened formulas. The majority (94%) of thickened formula combinations prepared to a target Mildly Thick consistency produced thickened formula that was thinner or thicker than the target. In contrast, the majority (76%) of thickened formula combinations prepared to a target Moderately Thick (IDDSI Level 3) consistency produced thickened formula that was equivalent to the target consistency. A statistically significant relationship was found between mixing methods and resulting IDDSI category for samples mixed to a target of Moderately Thick. The thickening agent and method of mixing must be considered carefully when preparing infant formulas to Mildly and Moderately Thick target IDDSI categories. Based on results of this study, it is recommended that providers utilize a clinical testing method, such as the IDDSI Syringe Flow Test, when attempting to create a Mildly Thick formula consistency.