Development of a simple and objective evaluation method for thickened liquids using funnels

Area of Science:

• Food Science
• Biomedical Engineering
• Clinical Nutrition

Background:

• Dysphagia patients often aspirate thin liquids, necessitating thickened liquids for safety.
• Current methods for evaluating liquid thickness (viscometers) are expensive and complex.
• A simple, objective method is needed for consistent liquid thickness in clinical settings.

Purpose of the Study:

• To develop and validate a simple, objective funnel-based method for evaluating thickened liquids.
• To assess the correlation between the funnel method and sensory evaluation of liquid thickness.
• To provide a practical tool for healthcare kitchens to ensure appropriate liquid viscosity.

Main Methods:

• Developed a method using funnels of varying stem sizes to measure outflow times of thickened liquids.
• Tested five thickened liquids, including nutritional supplements and those thickened with guar and xanthan gum.
• Measured outflow times with a standard volume (30 mL) and analyzed viscosity at specific shear rates (10-50 s⁻¹).

Main Results:

• Outflow time through funnels (5.3-9.0 mm stem ID) correlated with liquid viscosity at shear rates of 10-50 s⁻¹.
• A strong correlation (r=0.946) was found between funnel outflow time and sensory evaluation for a 5.3 mm stem funnel.
• The funnel method demonstrated superior correlation with sensory evaluation compared to the line spread test (LST).

Conclusions:

• The funnel method provides a simple, objective, and cost-effective way to evaluate thickened liquid viscosity.
• This method is suitable for use in hospital and nursing home kitchens.
• It offers a practical alternative to expensive viscometers and shows better agreement with sensory perception than LST, especially for certain thickening agents.