Texture study of gluten-free cookies added with fibre by instrumental, image and sensory analysis

The alternative starches and flours used in gluten-free bakery in replacement of wheat have very low quantities of fibre. As a consequence, the resulting products have a poor nutritional profile in terms of this nutrient, and present technological difficulties and quality challenges related to texture. In this work, the texture of gluten-free cookies added with a source of fibre, and its impact in consumer's perception was studied. Due to the complexity of texture, its description was assessed through three different methods: instrumental force/deformation measurements, image analysis, and sensory evaluation, in order to reach a better representation of the product's texture and to compare the different techniques' capacity to describe it. The instrumental method showed that the control cookie presented a higher maximum force (F-max), indicating that this sample was significantly more resistant to fracture, while the cookie added with fibre showed a lower deformation before fracture (Delta F-max), which corresponds to a more fragile structure. The results obtained by image texture analysis using the Gray Level Co-occurrence Matrix method were consistent with those determined by instrumental analysis. Good correlations were reached between the instrumental firmness and the five image parameters, showing the capacity of image attributes to predict mechanical properties of the samples. Sensory analysis with consumers showed a good acceptability of the product, but was not as useful to detect small differences between cookies. The study of texture through different techniques could be an interesting approach to attain complementary information, providing a more comprehensive perspective of this multifaceted attribute.