IDDSI Level 4 – Pureed – Passing the IDDSI Testing Methods for PU4

It has been great that the IDDSI Framework has brought both a standardised language and objective testing methods. These advances in dysphagia diet terminology underpin the improved safety that is achievable in dysphagia foodservice delivery. We will take a look here at passing the IDDSI Testing Methods for PU4.

We know, as chefs, cooking with food every day, the challenges that different ingredients, and combinations of ingredients, pose when we are trying to achieve textures that must pass certain auditing requirements.

In this article we will look at the Critical Tests, set out on the PU4 IDDSI Audit Sheet to explore some considerations of food preparation that will result in the successful passing of the IDDSI Testing Methods for PU4.

Finely Processing Foods

At a wide angled view food is made up of solids and liquids. The way these solids and liquids are structured, in regular food items, is a result of a combination of factors: the ingredients, preparation processes and cooking methods (among other things).

Finely processing ingredients, or whole components of dishes, will break down the original structure and create ‘purees’ made up of tiny pieces of food surrounded by liquid, the moisture found in the food.

The characteristics of these resultant purees will reflect the nature of the solid components (starches, fats, protein, etc…); the nature of the liquid components (water, solutes, fats, etc…); and the available proportion of each – Solid:Liquid availability.

An example of different characteristics resulting from finely processing methods can be illustrated with a ‘ham and salad sandwich’ verses, say, ‘tinned peaches’.

Theoretically, both can be finely processed, however, the sandwich has far less available liquid, in proportion to the solids, and has relatively high proportions of starch and protein. This will lead to a densely thick and sticky puree.

The tinned peaches, however, are mainly structural fibre and water (with a few other bits) at proportions that give rise to a wet, cohesive, and non-sticky puree.

Passing the IDDSI Testing Methods for PU4

So with this, basic understanding, let’s take a look at the IDDSI critical testing methods

Critical: Appearance- Completely Smooth

By and large, the longer an item is finely processed for, the smaller the solids will become, and the finer (smoother) the texture will be. If there are any properties that are too firm to be broken down by the equipment being used, these will fragment and be dispersed throughout the puree. This can be remedied by removing or tenderising, such textures before finely processing, or passing the resultant puree through a sieve.

Critical: Fork Drip Test – Food sits in a mound above the dinner fork (a small amount may form a tail below the dinner fork) and; Does not drip or flow continuously through dinner fork

Without going into the details on Newtonian fluids, non-Newtonian fluids, stress and sheer rates in this article – practically speaking, this will mainly be to do with the proportions of liquid in the puree. The greater the proportion of liquid, the more it will flow. You will generally find that the finer the solid particles are in the puree, the more volume of liquid can be held without separation. However, if you are finding that your PU4 purees do separate slightly, this can be remedied with the addition of a thickening agent that will trap the liquid.

Critical: Spoon Tilt Test – Holds shape on teaspoon; Food slides off teaspoon with little food left on teaspoon (i.e. not sticky); and May spread or slump slowly on a flat plate

In practical terms, purees that don’t pass the IDDSI Spoon Tilt Test are either too thick or they are made up of sticky components (such as starches or combinations of elements that create sticky textures).

In some cases adding a greater proportion of liquid can have the desired effect, although this may cause the puree to fail the IDDSI Fork Drip Test. Where sticky characteristics persist texturisation with a combination of purees has been shown to be an extremely effective method.

When making PU4 foods it is important to note that ALL critical tests are successful and that the food is not gelled and cannot be picked up (as set out in the notes on the IDDSI Audit Sheet). The recipe must also be robust enough that it continues to pass the tests over the course of the entire meal time.

For more details on our health and social care sector training that is now widely used across NHS and private care providers in the UK you can follow this link: Online Dysphagia Diets for IDDSI Course