Texture analysis of wet petfood

Introduction

The texture of a substance is a complex and subjective notion dependent on many different criteria; in particular, when related to petfoods, several questions are immediately apparent. What is the preferred texture for an animal foodstuff? Does texture affect its palatability? What are the links between a product’s texture and its packaging? Can texture affect how easily an owner finds the food to use? How is the texture of a new product characterized, and how do the textures compare before and after a product is reformulated? What are the key parameters in the manufacturing process that influence the final texture? And how is the texture of a marketed petfood maintained between batches?

Rheology and texture analysis

Rheology is the branch of science that studies the flow, deformation and rupture of powders, liquids, or solids when subjected to stress. The rheological properties of a foodstuff, as determined by measuring the application of a force to the product and how it is deformed by that force as a function of time, affect its texture 1. Different analytical methods can be employed to assess solids, liquids, gels and powders 2; for petfoods one of the most useful is the texturometer (Figure 1). This versatile device employs probes or modules to analyze a food product in various ways (Figure 2); penetration and compression tests are the most commonly employed methods for both dry and wet petfoods 3.

Texture profile analysis

The texture profile analysis (TPA) produced by the texturometer is now widely used in the industry and can evaluate different texture parameters for a petfood using a single experiment. It involves subjecting a food sample to a double compression (to mimic the chewing process) under standardized conditions – for example, the compression and return speeds must be the same, the sample must be deformed to a certain percentage of its initial height, and the sample size must be uniform. Using data from these tests allows construction of a force-time graph (Figure 3), making it possible to extract textural properties from a food product and correlate them with sensory analysis results. The parameters obtained with a TPA test, and the definitions for each parameter, are shown in Table 1.

This analytical method originally made it possible to obtain both primary parameters (Hardness, Cohesiveness, Springiness and Adhesiveness) and secondary parameters (Fracturability, Chewiness and Gumminess) for a foodstuff. However, recent developments have allowed analysis of other parameters, and so the technical team must identify the most relevant textural parameters for any given product before commencing a study.

The TPA analysis & Royal Canin

The ability to characterize the texture of wet products is an invaluable asset, especially since Royal Canin has such a wide variety and complexity of recipes. At present, the “Hardness” parameter resulting from the first TPA test compression seems to be the most discriminating to characterize a “loaf” type foodstuff. Product texture measurement obviously requires the implementation of several methods to obtain a full profile for a foodstuff. For quality control, and to use texture as a key quality attribute, such methods must be able to be deployed quickly in the manufacturing plant and should not be prohibitive in terms of time and cost. The TPA test thus remains a primary tool for both new product development and for ongoing assessment of existing products.