## 3 Results and Discussion  
Cashew gum is a brown resin extracted from the tree trunk, which is aggregated with inorganic salts, proteins, lignins, and nucleic acids from adjacent structures [2]. For this reason, and given the need to standardize the material to be worked on, to obtain reproducibility and confidence in the results, it is necessary to purify the cashew gum before its application. Therefore, cashew gum was purified by four different methodologies (P1-P4) to compare them with each other and select the best one for reproduction. When purified, the samples changed the color (Figure 2A), ranging from a white to light brown powder. This difference may also be related to the maturity of the donor tree and the environment in which it was found [25]. The yield obtained by each methodology was 58.40%, 54.36%, 72.66% and 40.61% for P1-P4, respectively. Previous studies that used the same methodology as P1 and P2 found 67% and 78%, respectively [32]. The lower yield observed in P1, P2 and P4 may be associated with the amount of solvent and the process used during purification [32]. On the other hand, P3 had the highest yield due to the potential for hydrolysis and polysaccharides cleavage from the ultrasonic probe sonicator used in the process [33]. Figure 2: **(A)** Cashew gum after purification by different methodologies, using hydrogen peroxide (P1), acetone (P2), ultrasonic probe sonicator (P3), and microwave (P4); **(B)** Percentage of CG moisture content after drying by infrared radiation at 60 \({}^{\circ}\)C; **(C)** DSC curves of CG from room temperature to 473.15 K (200 \({}^{\circ}\)C) and heating rate of 283.15 K (10 \({}^{\circ}\)C); **(D)** TG/DTG curve of CG under dynamic nitrogen atmosphere (50 mL-min\({}^{-1}\)), \(\beta\) = 10 \({}^{\circ}\)C, and m = 8.5 \(\pm\) 0.5 mg; **(E)** X-ray Diffractogram of CG with 20 reflection angle, monitored from 2\({}^{\circ}\) to 70\({}^{\circ}\) at a scan speed of 1\({}^{\circ}\) min\({}^{-1}\), 40 kV/30 mA; **(F)** FTIR spectra of CG in Kbr pellet. The percentage of total ash and the moisture content are critical parameters of fundamental purity to be analyzed, considering that the lower their indexes, the higher the quality of the purified gum [24]. The % of total ash after the CG purifications were 0.69%, 0.61%, 0.34% and 1.05% for P1-P4, respectively. Previous studies which used similar methodologies as P1 and P2 had the % of total ash around 0.95% [34] and 0.71% [35], suggesting potential in the addition of hydrogen peroxide and acetone in the process. However, the highlight was the addition of an ultrasonic probe sonicator on P3, which results in less than 0.40% of ash. The desirable level accepted by the pharmaceutical and food industries is 4% [24]. The moisture contents were analyzed by the gravimetric method in an analytical balance with coupled infrared radiation drying system. All samples reached the stability of the weight after 5 min, resulting in residual moisture values of 12.9%, 10.34%, 10.71% and 14.81% for P1-P4, respectively (Figure 2B). These percentages are associated with drying efficiency, powder fluidity, viscosity, and storage stability due to their effect on the glass transition and crystallization behavior [36]. The TGA/DTG presented three stages of decomposition for all samples analyzed (Figure 2C). The first event it was in the temperature range 25-197 \({}^{\circ}\)C with a variation of \(\Delta\)m\({}_{1}\) = 11.55% and T\({}_{\text{peak DTG}}\) = 55.59 \({}^{\circ}\)C; \(\Delta\)m\({}_{1}\) = 11.87% and T\({}_{\text{peak DTG}}\) = 54.97 \({}^{\circ}\)C; \(\Delta\)m\({}_{1}\) = 11.96% and T\({}_{\text{peak DTG}}\) = 56.22 \({}^{\circ}\)C; and \(\Delta\)m\({}_{1}\) = 8.74% and T\({}_{\text{peak DTG}}\) = 86.05 \({}^{\circ}\)C for P1-P4, respectively. This first step is widely elucidated in the literature and is related to the loss of free and bound water molecules of the CG [37]. It is well-known that the gums, in general, present a mainly double decomposition pattern, and this stage starts above 200 \({}^{\circ}\)C [38].