3.5.1. Rheological Properties

According to the rheological characterization results, RSG, FSG, and CSG gave the highest K, K, recovery values and thixotropic degree at the highest concentrations used. RSG, FSG, and CSG were compared with commercial gums at these concentrations. In determining the concentrations of commercial gums in mayonnaise production, the concentrations that gave successful results in the literature were taken into account. The steady shear rheogram of vegan mayonnaise samples was shown in Figure 7, which was absolute evidence of shear-thinning behavior (pseudoplastic behavior) of vegan mayonnaise. This typical behavior was reported for vegan mayonnaise by other researchers [71,72]. It can be concluded from Figure 7 that the mayonnaise sample that formulated the CG and FG had the highest shear-thinning behavior, followed by GG.

The viscoelastic characteristics of the vegan mayonnaise samples obtained by frequency sweep measurement were characterized and shown in Figure 7. As seen, G was greater than G across the measured frequency range and both G and G were hardly influenced by frequency change (Figure 6). It can be concluded that all vegan mayonnaise samples showed more solid-like properties. This conclusion was conducted by [73] for mayonnaise formulated with micronized konjac gel. CG-VM samples had the highest G and G values.

Figure 7 indicated the 3-ITT rheological properties of the vegan mayonnaise samples. Due to deformations during high-speed mixing and homogenization, as well as during consumption, such as when the packed food is shaken or pressed, thixotropic behavior is crucial for O/W emulsions, notably in vegan mayonnaise with low oil content. As can be observed in Figure 7, all samples showed thixotropic behavior in the third interval. Mayonnaise samples lost their viscoelastic characteristics after severe shear deformation but recovered them after a second period. These findings suggested that all mayonnaise samples may maintain their viscoelastic character throughout food processing involving a large amount of abrupt deformation, such as homogenization or pumping, as well as consumption under shaking and squeezing. This is the ideal flow behavior for mayonnaise.

**Figure 7.** Rheological properties of vegan mayonnaise samples formulated with different gums.FG-VM: flaxseed oil byproduct gum vegan mayonnaise, CG-VM: chia seed oil byproduct gum vegan mayonnaise, RG-VM: rocket seed oil by-product gum vegan mayonnaise, GG-VM: guar gum vegan mayonnaise, XG-VM: xanthan gum vegan mayonnaise, AG-VM: gum Arabic vegan mayonnaise.(**A**) Steady shear rheological properties of the low-fat vegan mayonnaise samples, (**B-1**) Viscoelastic behavior of the low-fat vegan mayonnaise samples formulated with CG, FG, and RG, (**B-2**) Viscoelastic behavior of the low-fat vegan mayonnaise samples formulated with AG, GG, and XG, (**C**) 3-ITT rheological properties of the low-fat vegan mayonnaise samples.

Table 6 presented the rheological properties of low-fat vegan mayonnaise samples prepared with a different type of gum. The flow parameters of the flow index (n), consistency index (K), and coefficient of determination (R2) were shown in Table 6. The n values were 0.208–0.769, indicating that all mayonnaise samples expected for AG-VM were pseudoplastic fluids (*n* < 1). The n values were reported as lower than 1 for some commercial mayonnaises and vegan mayonnaise samples [74–77]. K values of vegan mayonnaise samples were determined between 0.007 and 38.582 Pa·<sup>s</sup>n. CG-VM and FG-VM samples had similar and highest K values, explaining the strongest non-Newtonian behavior.

Table 6 indicated the dynamic power-law parameters of vegan mayonnaise samples. K and K values of samples were found as 0.012–43.317 Pa·s<sup>n</sup> and 0.006–30.423 Pa·<sup>s</sup>n, respectively. For the generation of dense viscoelastic interfacial networks at the air/water interface, neutral protein-polysaccharide complexes are recommended. These networks can minimize a thin-gas film's permeability while also promoting foam stability, resulting in much lower interfacial area loss and air bubble coalescence rates. While unevenly charged

protein-polysaccharide solutions can stabilize electrostatic repulsion forces between droplet surfaces and induce stability against flocculation and creaming of emulsions, they can also cause flocculation and creaming.



CG-VM: vegan mayonnaise contained chia seed byproduct gum, FG-VM: vegan mayonnaise contained flaxseed byproduct gum, RG-VM: vegan mayonnaise contained rocket seed byproduct gum, AG-VM: vegan mayonnaise contained Arabic gum, GG-VM: vegan mayonnaise contained guar gum, XG-VM: vegan mayonnaise contained xanthan gum; K, K, and K: consistency coefficient (Pa·<sup>s</sup>n); n, <sup>n</sup>, and n: flow behavior index values; *G*0: the initial values of the storage modulus; *Ge*: the equilibrium storage modulus; k: the rate constant of recovery of the sample; R2: determination of coefficient. \* low-fat vegan mayonnaise samples contain 30% vegetable oil and 1% lecithin. A different uppercase letter in the same column indicates statistical significance.

### 3.5.2. Zeta Potential and Particle Size

Zeta (ζ) potential is an important parameter that shows whether O/W emulsions can remain stable for a long time. As the ζ-potential value moves away from 0, in other words, the system having a negative or positive charge is a positive indicator for the long stability of the product. Table 7 showed that the ζ-potential values of the samples were found between (−42.80) and (−31.90) mV. The first interpretation we can make by looking at these values is that the ζ-potential value of all samples is higher than 0 or that the samples are stable products to a certain degree. The absolute ζ-potential values of our vegan mayonnaise samples were similar except for AG-VM, indicating that the samples can remain stable in these formulations for a long time. The fact that gum forms a compact structure by reducing the mobility of the mobile phase in increasing the stability of mayonnaise samples, thus reducing the action potential of the oil molecules in this tight structure and restricting the interaction of the droplets play a primary role [77]. The fact that the oil droplets have a certain electrical potential and interact with each other thanks to the electrostatic repulsive force, preventing flocculation. The zeta potential of samples prepared with gums obtained from byproducts is similar to commercial gums, indicating

that the gums obtained from these byproducts can be successfully applied in an emulsion product, such as mayonnaise and salad dressing.


**Table 7.** The zeta potential and particle size of vegan mayonnaise samples with a different type of gum.

CG-VM: vegan mayonnaise contained chia seed byproduct gum, FG-VM: vegan mayonnaise contained flaxseed byproduct gum, RG-VM: vegan mayonnaise contained rocket seed byproduct gum, AG-VM: vegan mayonnaise contained Arabic gum, GG-VM: vegan mayonnaise contained guar gum, XG-VM: vegan mayonnaise contained xanthan gum. ζ-Potential: zeta-potential (mV); PdI: polydispersity index; d32: the oil particle size (μm). A different uppercase letter in the same column indicates statistical significance.

The oil particle size (d32) and PdI value of the samples were found as 1240.00–8581.33 μm, and 0.249–0.701, respectively. The researchers emphasized that the oil particle diameter decreased significantly as the polysaccharide concentration increased [78,79]. As can be seen, the mayonnaise samples containing AG and RG exhibited lower particle size and PdI value as compared to other mayonnaise samples. Also, all samples have a sufficient zeta potential value.

### 3.5.3. Oxidative Stability (at 90 ◦C)

The oxidative stability of the vegan mayonnaise samples was determined with the Oxitest device, and the IP values of the samples were recorded. Table 8 showed the IP values of the samples. The IP values varied between 4:38 and 13:44 h. The sample prepared with xanthan gum showed the lowest IP value. The IP values of the samples prepared with gums obtained from byproducts were higher than the vegan mayonnaise samples prepared with xanthan gum. The IP value of the sample prepared with RSG was much higher than other samples. The very high IP value of the sample prepared with RSG can be explained by the RSG concentration. Due to the low consistency of RSG, it was used at the level of 5%. During the extraction of RSG, antioxidant products, such as phenolic compounds, may have transferred to gum solution and caused higher IP value. The higher IP value of FSG and RSG than xanthan gum. This result indicated that gums obtained from byproducts could exhibit a favorable condition in terms of oxidative stability as well as providing desirable consistency.

**Table 8.** The induction period (IP (h)) of vegan mayonnaise samples with a different type of gum at 90 ◦C.


CG-VM: vegan mayonnaise contained chia seed byproduct gum, FG-VM: vegan mayonnaise contained flaxseed byproduct gum, RG-VM: vegan mayonnaise contained rocket seed byproduct gum, AG-VM: vegan mayonnaise contained Arabic gum, GG-VM: vegan mayonnaise contained guar gum, XG-VM: vegan mayonnaise contained xanthan gum. IP: induction period (h). A different uppercase letter in the same column indicates statistical significance.
