*3.4. Texture Properties of the Laminaria-Psyllium Gel Systems*

Texture is a major quality parameter, and is crucial for consumer acceptance. Figure 4 presents the texture profiles of the samples and the commercial references.

**Figure 4.** Texture profiles of Psy (control) and PsyL (**a**), *Laminaria-Psyllium* gels (**b**), *Laminaria-Psyllium* gels subjected to ultrasonic treatment (**c**), and commercial products (**d**). The differences in the texturograms reflect the different sizes and shapes of the commercial products. 93

Each food system (e.g., jelly, mayonnaise, and baby food) presents texture properties that are specific, easily recognizable, and desired by the consumers. Despite the information given by the texture profile, the use of this methodology is very limited in the scientific literature. To our knowledge, no published studies refer to the texture features of commercial gelled products, therefore we show here some texture profiles of different commercial food products to illustrate the data for these systems to be used as a target for further product development. Based on these texture profiles (Figure 4d), three groups of samples can be discriminated: one composed of *Pâté*, *Pet Food* and *Jam*; another with *Baby Food* and *Guacamole*; and a third with *Jelly Gum,* whose graph is shown separately. In the first group of samples, the rupture point occurred at a low break distance, and the force reached a plateau until the probe retracted from the sample. This mechanical behavior was similar to what we found in LoUS.Psy\_75.25 (Figure 4c) and has also been reported by Genovese and co-workers [30] for pectin gels. The control and PsyL texture profiles (Figure 4a) were similar to the one obtained by Figueroa et al. [21] for fruit jellies with *Psyllium*, although with much lower magnitude.

From the texture profiles depicted, the firmness, adhesiveness, and cohesiveness values were calculated (Table 4).


**Table 4.** Texture parameters (firmness, adhesiveness and cohesiveness) of the gels developed and commercial references.

Psy (control), *Psyllium* gels prepared in water; PsyL, *Psyllium* gels prepared in autohydrolysis liquor; *Laminaria-Psyllium* gels: Lo.Psy\_25.75, Lo.Psy\_50.50, and LoPsy\_75.25; *Laminaria* with ultrasonic treatment-*Psyllium* gels: LoUS.Psy\_25.75, LoUS.Psy\_50.50, and LoUSPsy\_75.25. Data are presented as the mean ± sd. Different letters in the same column correspond to significant differences (*p* < 0.05).

In general, it can be said that the firmness of the *Laminaria-Psyllium* system is independent of the level of *Laminaria* incorporation and the ultrasonic (US) pre-treatment. On the other hand, there are strong negative correlations between the adhesiveness (r = −0.888, *p* < 0.05) and cohesiveness (r = −0.844, *p* < 0.05) parameters and *Laminaria* concentration, and again, the US pre-treatment did not make any change. The fact that adhesiveness can be adjusted by keeping the firmness values constant could be useful in product development.

In a previous study by the authors [17], it was found that the texture parameters, especially adhesiveness, of the alga purée-like mixtures varied according to the ultrasonic treatment. However, that difference was not maintained after the addition of *Psyllium*. Since PsyL did not show adhesiveness values that could explain this result, one can conclude that there is a synergistic effect of *Laminaria* and *Psyllium* in this texture parameter, stronger than mere addition. Based on these results and looking at the texture profiles of the samples (Figure 4a–c), one can conclude that the texture properties of *Laminaria-Psyllium* gels are governed by the alga, what is in agreement with the dynamic rheology results. Texture profiles (Figure 4) confirm the relevance of alga in the system.

The texture parameters of the commercial products varied greatly. Comparing the texture parameters of the gelled systems developed with those of the references (Table 4), the developed *Laminaria-Psyllium* gels presented similar values to the commercial products. Although the systems developed are not finished products, but binary systems consisting of alga purée and *Psyllium* gel, this is a good starting point for the development of enriched gelled food products. These *Laminaria* and *Psyllium* whole materials can be used as alternatives to the biopolymers that are usually added to build up structure in foods. This is in line with the food trends regarding the use of natural products over processed ones.

It should be pointed out that in this approach, we developed the *Laminaria-Psyllium* gels using water, but the gels could also be produced in the same way using the AH liquor extract, thus taking advantage of the soluble compounds present there, namely phenolic compounds with antioxidant capacity [17]. Due to the differences in texture and rheological features between the control and PsyL, it is plausible to assume that *Laminaria-Psyllium* gels prepared in AH liquor would present distinct mechanical properties.
