3.3.1. Visual Appearance

A heating/cooling cycle test was performed while the formulations were stored in an incubator. The temperature was alternated between 4 ◦C and 40 ◦C every 24 h during any period of time. This method is commonly used during the initial stage of developmental screening. Useful information relating to stability could be obtained from such tests [1]. The accelerated stability test of the deodorant cream with different concentrations of H-CMCH (0.5, 1.0, 1.5, 2.0, and 2.5% (*w*/*v*)) was performed at 4 ◦C in a refrigerator and 45 ◦C in a hot oven and a heating/cooling cycle for up to 6 cycles. The result of each formulation was randomly checked every 1 cycle by centrifugation at 6000× *g* for 20 min at 25 ◦C. Deodorant creams with 0.5 and 1.0% H-CMCH indicated acceptable stability after 6 cycles by less phase separation. For the cream containing 1.5–2.5% H-CMCH, higher phase separation and greater changes in color are evident, as shown in Figures 2–6. screening. Useful information relating to stability could be obtained from such tests [1]. The accelerated stability test of the deodorant cream with different concentrations of H-CMCH (0.5, 1.0, 1.5, 2.0, and 2.5% (*w*/*v*)) was performed at 4 °C in a refrigerator and 45 °C in a hot oven and a heating/cooling cycle for up to 6 cycles. The result of each formulation was randomly checked every 1 cycle by centrifugation at 6,000 × *g* for 20 min at 25 °C. Deodorant creams with 0.5 and 1.0% H-CMCH indicated acceptable stability after 6 cycles by less phase separation. For the cream containing 1.5–2.5% H-CMCH, higher phase separation and greater changes in color are evident, as shown in Figures 2–6. screening. Useful information relating to stability could be obtained from such tests [1]. The accelerated stability test of the deodorant cream with different concentrations of H-CMCH (0.5, 1.0, 1.5, 2.0, and 2.5% (*w*/*v*)) was performed at 4 °C in a refrigerator and 45 °C in a hot oven and a heating/cooling cycle for up to 6 cycles. The result of each formulation was randomly checked every 1 cycle by centrifugation at 6,000 × *g* for 20 min at 25 °C. Deodorant creams with 0.5 and 1.0% H-CMCH indicated acceptable stability after 6 cycles by less phase separation. For the cream containing 1.5–2.5% H-CMCH, higher phase separation and greater changes in color are evident, as shown in Figures 2–6.

A heating/cooling cycle test was performed while the formulations were stored in an

incubator. The temperature was alternated between 4 °C and 40 °C every 24 h during any

A heating/cooling cycle test was performed while the formulations were stored in an

*Polymers* **2021**, *13*, x FOR PEER REVIEW 9 of 18

*Polymers* **2021**, *13*, x FOR PEER REVIEW 9 of 18

**Figure 2.** Deodorant cream with 0.5% H-CMCH by heating/cooling cycle; (**a**) cycle 0, (**b**) cycle 1, (**c**) cycle 2, (**d**) cycle 3, (**e**) cycle 4, (**f**) cycle 5, and (**g**) cycle 6. **Figure 2.** Deodorant cream with 0.5% H-CMCH by heating/cooling cycle; (**a**) cycle 0, (**b**) cycle 1, (**c**) cycle 2, (**d**) cycle 3, (**e**) cycle 4, (**f**) cycle 5, and (**g**) cycle 6. **Figure 2.** Deodorant cream with 0.5% H-CMCH by heating/cooling cycle; (**a**) cycle 0, (**b**) cycle 1, (**c**) cycle 2, (**d**) cycle 3, (**e**) cycle 4, (**f**) cycle 5, and (**g**) cycle 6.

**Figure 3.** Deodorant cream with 1.0% H-CMCH by heating/cooling cycle; (**a**) cycle 0, (**b**) cycle 1, (**c**) **Figure 3.** Deodorant cream with 1.0% H-CMCH by heating/cooling cycle; (**a**) cycle 0, (**b**) cycle 1, (**c**) cycle 2, (**d**) cycle 3, (**e**) cycle 4, (**f**) cycle 5, and (**g**) cycle 6. **Figure 3.** Deodorant cream with 1.0% H-CMCH by heating/cooling cycle; (**a**) cycle 0, (**b**) cycle 1, (**c**) cycle 2, (**d**) cycle 3, (**e**) cycle 4, (**f**) cycle 5, and (**g**) cycle 6.

cycle 2, (**d**) cycle 3, (**e**) cycle 4, (**f**) cycle 5, and (**g**) cycle 6.

*Polymers* **2021**, *13*, x FOR PEER REVIEW 10 of 18

**Figure 4.** Deodorant cream with 1.5% H-CMCH by heating/cooling cycle; (**a**) cycle 0, (**b**) cycle 1, (**c**) cycle 2, (**d**) cycle 3, (**e**) cycle 4, (**f**) cycle 5, and (**g**) cycle 6. **Figure 4.** Deodorant cream with 1.5% H-CMCH by heating/cooling cycle; (**a**) cycle 0, (**b**) cycle 1, (**c**) cycle 2, (**d**) cycle 3, (**e**) cycle 4, (**f**) cycle 5, and (**g**) cycle 6. **Figure 4.** Deodorant cream with 1.5% H-CMCH by heating/cooling cycle; (**a**) cycle 0, (**b**) cycle 1, (**c**) cycle 2, (**d**) cycle 3, (**e**) cycle 4, (**f**) cycle 5, and (**g**) cycle 6.

**Figure 5.** Deodorant cream with 2.0% H-CMCH by heating/cooling cycle; (**a**) cycle 0, (**b**) cycle 1, (**c**) **Figure 5.** Deodorant cream with 2.0% H-CMCH by heating/cooling cycle; (**a**) cycle 0, (**b**) cycle 1, (**c**) **Figure 5.** Deodorant cream with 2.0% H-CMCH by heating/cooling cycle; (**a**) cycle 0, (**b**) cycle 1, (**c**) cycle 2, (**d**) cycle 3, (**e**) cycle 4, (**f**) cycle 5, and (**g**) cycle 6.

**Figure 6.** Deodorant cream with 2.5% H-CMCH by heating/cooling cycle; (**a**) cycle 0, (**b**) cycle 1, (**c**)

**Figure 6.** Deodorant cream with 2.5% H-CMCH by heating/cooling cycle; (**a**) cycle 0, (**b**) cycle 1, (**c**)

the heating/cooling cycle method, at the 0 cycle of the stability study the developed deodorant cream samples had pH in the range of 6.32–6.41. After the end of the test, the pH values of all five formulas of deodorant products were found to be in the range of 6.26 to 6.37. This was similar to the pH of human skin and thus suitable for application to the

the heating/cooling cycle method, at the 0 cycle of the stability study the developed deodorant cream samples had pH in the range of 6.32–6.41. After the end of the test, the pH values of all five formulas of deodorant products were found to be in the range of 6.26 to 6.37. This was similar to the pH of human skin and thus suitable for application to the

The measurement of pH for all five deodorant formulas in the accelerated state with

The measurement of pH for all five deodorant formulas in the accelerated state with

cycle 2, (**d**) cycle 3, (**e**) cycle 4, (**f**) cycle 5, and (**g**): cycle 6.

cycle 2, (**d**) cycle 3, (**e**) cycle 4, (**f**) cycle 5, and (**g**): cycle 6.

3.3.2. pH Value

3.3.2. pH Value

cycle 2, (**d**) cycle 3, (**e**) cycle 4, (**f**) cycle 5, and (**g**) cycle 6.

cycle 2, (**d**) cycle 3, (**e**) cycle 4, (**f**) cycle 5, and (**g**) cycle 6.

cycle 2, (**d**) cycle 3, (**e**) cycle 4, (**f**) cycle 5, and (**g**): cycle 6.

cycle 2, (**d**) cycle 3, (**e**) cycle 4, (**f**) cycle 5, and (**g**) cycle 6.

**Figure 4.** Deodorant cream with 1.5% H-CMCH by heating/cooling cycle; (**a**) cycle 0, (**b**) cycle 1, (**c**)

**Figure 5.** Deodorant cream with 2.0% H-CMCH by heating/cooling cycle; (**a**) cycle 0, (**b**) cycle 1, (**c**)

**Figure 6.** Deodorant cream with 2.5% H-CMCH by heating/cooling cycle; (**a**) cycle 0, (**b**) cycle 1, (**c**) cycle 2, (**d**) cycle 3, (**e**) cycle 4, (**f**) cycle 5, and (**g**) cycle 6. **Figure 6.** Deodorant cream with 2.5% H-CMCH by heating/cooling cycle; (**a**) cycle 0, (**b**) cycle 1, (**c**) cycle 2, (**d**) cycle 3, (**e**) cycle 4, (**f**) cycle 5, and (**g**) cycle 6.

#### 3.3.2. pH Value

3.3.2. pH Value The measurement of pH for all five deodorant formulas in the accelerated state with the heating/cooling cycle method, at the 0 cycle of the stability study the developed deodorant cream samples had pH in the range of 6.32–6.41. After the end of the test, the pH values of all five formulas of deodorant products were found to be in the range of 6.26 to 6.37. This was similar to the pH of human skin and thus suitable for application to the The measurement of pH for all five deodorant formulas in the accelerated state with the heating/cooling cycle method, at the 0 cycle of the stability study the developed deodorant cream samples had pH in the range of 6.32–6.41. After the end of the test, the pH values of all five formulas of deodorant products were found to be in the range of 6.26 to 6.37. This was similar to the pH of human skin and thus suitable for application to the skin with a good stability; for example, the cream texture was a fine opaque white. While applying, the consistency of the cream spreads well; it is easy to blend and can be absorbed into the skin and enhance the moisture of skin for a long time. Moreover, an effective cream should have a pH of about 6.55 [40]. After acceleration to cycle 6, it was found that the pH value decreased significantly (*p* < 0.05), with the pH value in the range of 6.34–6.37 as shown in Figure S2. The pH range should not be too acidic or alkaline, because irritation to the skin might be unavoidable. The pH mitigation is probably due to separation of the cream emulsion from its matrix and ionization, resulting in net negative charge and causing the rise in acidity [41,42]. To avoid exceedingly high pH values beyond the skin's physiological range, a preservative solution was added to the formulations. Implementation of sodium benzoate or sodium salt of benzoic acid also facilitates stabilization of the skin's pH. In general, sodium benzoate is commonly used in combination with antiseptics as food preservatives, cosmetics, and medicines [42]. The oxidative/reductive mechanisms, deactivating properties, and safety assessment of benzoic acid or related compounds in biological systems are well documented in the literature [43–45]. Considering the kinetic rate (*k*) of pH, it was found that increasing CMCH content (0.5–2.5%) in the formula affected the decrease of the pH's *k*-value when compared to the formula with 0.5% (*w*/*v*) CMCH. It was evident that cream containing 0.5% (*w*/*v*) H-CMCH showed a good pH stability, which plateaued after six cycles. For other samples, the pH decrease was still ongoing in a linear trend after six cycles. This is probably due to the implementation of higher H-CMCH concentration.

#### 3.3.3. Viscosity

Viscosity is one of key parameters indicating cream quality. The forecasting of this parameter is commonly performed in accelerated stability testing [1]. From the viscosity stability of the deodorant cream after passing the accelerated state for up to six cycles, the results showed that H1 and H2 were not separated and precipitated; the cream texture

had a smooth appearance. The viscosity was not significantly changed (*p* ≥ 0.05), being in the ranges 234–300 and 231–313 cP, respectively. H3, H4, and H5 started to separate. The viscosity was significantly decreased (*p* < 0.05), with values in the ranges 154–363, 125–464, and 114–500 cP, respectively, as shown in Figure S3. As for the viscosity changing rate (*k*), as the CMCH content increased from 0.5% to 2.5% (*w*/*v*), the *k*-value increased (from 9.9 to 71.6 cP/cycle). The increasing CMCH content could have affected the decrease in the viscosity value and stability under changing temperature. CMCH is an amphiprotic ether of chitosan derivative. The functional groups include active hydroxyl (–OH), carboxyl (–COOH), and amine (–NH2) in the molecule. CMCH is soluble in water at neutral pH (pH = 7). It also exhibits high viscosity as well as film and gel forming capability, which encourages its use in foods and cosmetics [14]. These are excellent properties for work as stabilizers in emulsion preparation [14]. Chaiwong et al. [23] have reported that the greater solubility also corresponded to the decrease in viscosity of the low- and mediummolecular-weight CMCHs, which are slightly different, but for the high-MW CMCH, it required significantly higher viscosity. This could be explained by the fact that CMCHs with chains longer or higher in MW were contributing to the gel. Moreover, it also has been pointed out by Tzaneva et al. [46] that with increasing temperature of emulsions, viscosity and shear stress decreased with different gradients. Using CMCH as a stabilizing agent indicates the ability of its rheological characteristics. After measurement of thermophysical properties by TGA/DTA analysis, it can be concluded that CMCH is suitable to work in the heating process and sterilization at temperatures up to 220 ◦C without changing the quality of components. The emulsions containing 0.3–0.5% (*w*/*v*) of CMCH could be applied in terms of pharmaceutical and cosmetic oil/water emulsions.3.3.4. Color L\*, a\*, b\* and ∆E.

Color measurements with the colorimeter of deodorant creams with concentrations of 0.5, 1.0, 1.5, 2.0, and 2.5% (*w*/*v*) H-CMCH (H1, H2, H3, H4, and H5) were carried out during the accelerated stability test under 4 ◦C in a refrigerator and 45 ◦C in an incubator by heating/cooling cycle (4 ◦C, 24 h and 45 ◦C, 24 h) for six cycles. Defined by the Commission Internationale de l'Eclairage (CIE), the L\*, a\*, and b\* color space was modeled after a color-opponent theory. As L\* indicates lightness, a\* is the red/green coordinate, and b\* is the yellow/blue coordinate. The results showed that all five formulas of deodorant cream have an initial L\* value (cycle 0) in the range of 79.63–80.07. Moreover, it was found that as the number of cycles of the acceleration test increased, the brightness of five deodorant formulas was significantly reduced (*p* < 0.05), as shown in Figure S4. The H4 and H5 deodorant creams had the lowest L\* values compared with H1, H2, and H3 at accelerated cycles 3–6. The separation is caused by high-speed centrifugation, which can accelerate the emulsion precipitation. A good emulsion must withstand a long centrifugal force of 5000–10,000× *g* for 30 min without separation. Shaking or stirring causes more particles in the emulsion to be more mixed. Moreover, reducing the viscosity accelerates the integration of the internal or dispersed phase. This acceleration is achieved by continuously centrifuging the emulsion. Normally, the emulsion stability limited by agglomeration, sedimentation, viscosity of the aqueous phase and rheological properties of the emulsion [47]. This is a result of disintegration or changes in the structure of important substances in the ME and H-CMCH.

For a\* (red/green coordinate) values, the result is shown in Figure S5 when considering each formula of deodorant cream during the accelerated stability test for six cycles. It was found that the a\* tended to increase in cycle 2 and tended to decrease in cycle 3 until the end of storage. For each cycle in accelerated storage, the results showed that the a\* value of the cream deodorant formulas H1, H2, and H3 in cycles 3–6 were in steady decline (*p* ≥ 0.05), ranging from 1.41 to 1.43. Due to the instability of deodorant cream with poor emulsion and lower smoothness, it was clearly seen that the consistency of the cream changed as the number of stability tests increased.

For b\* (yellow/blue coordinate) values, the result is shown in Figure S6 when considering each formula of deodorant cream during the accelerated stability test for six cycles. It was found that there was a tendency of the b\* value of the deodorant creams to increase

from the initial cycle (cycle 0) in the range of 2.1–2.5. For H4 and H5, the b\* increased from cycle 1 until the end; the values remained in the ranges 3.26–4.34 and 3.49–4.34, respectively. Meanwhile, b\* values for H2 and H3 tended to increase in cycle 2 and gradually remained constant until cycle 2–6 retention, ranging from 2.53–2.93. and 2.54–3.93. For H1, the b\* value changed at accelerated cycle 3 until the end of storage (cycles 2–6), being in the range of 2.63–3.43. This showed that increasing storage time had the effect of increasing the b\* value of deodorant creams (*p* < 0.05).

The total color difference (∆E) describes incorporated changes in the qualities of L\*, a\*, and b\* through the square root of the sum of square differences between two sets of complete color values [48]. The ∆E of deodorant creams with different concentrations of H-CMCH (0.5–2.5%) was measured during an accelerated stability test performed at 4 ◦C in a refrigerator and 45 ◦C in an incubator by heating/cooling cycle (4 ◦C and 45 ◦C for 24 h) for six cycles and compared with the basic formula deodorant cream, measuring with the CIE system colorimeter and calculating in the form of ∆E as in Figure 7. In comparison with the white basic deodorant cream, an effect on ∆E resulted. As the development of the deodorant cream involved adding mangosteen extract for the deodorizing agent, the initial color of all five deodorant formulas was white and pale yellow. This could be clearly observed with ∆E in the range of 2.65–3.06. However, as the retention period increased, the results showed that the stability of the cream changed, with visible separation occurring and unstable color, affecting the ∆E, which tended to increase significantly (*p* < 0.05). However, their colors were still acceptable by consumers if the ∆E values were less than 5 [49].

## *3.4. Deodorizing Activity*

Trans-2-nonenal is an unsaturated aldehyde produced from lipid oxidation, which generates an unpleasant greasy odor. It is known to be a major odor component detected from the bodies of old people [20]. Different concentrations (1, 10, and 100 mg/mL) of each sample—(a) ME, (b) standard EGCG, (c) prototype cream, (d) developed deodorant cream mixed ME and 1.0% H-CMCH (H2), and (e) prototype cream mixed with EGCG standard and 1.0% H-CMCH—were used for deodorizing activity against trans-2-nonenal as shown in Figure 8. It was found that the basic deodorant had the lowest deodorizing activity (18–37%). The deodorizing activity was significantly increased (*p* < 0.05) when ME and EGCG were added to the basic formula deodorant. However, the samples of deodorant cream with ME added and formula with EGCG added at a concentration of 1–100 mg/mL. The results showed that the deodorizing activities were in the range of 27–70% and 21–68%, respectively, which was slightly lower than ME and EGCG standards. The basic formula deodorant contains waxes and fatty acids (fatty acids or fatty alcohol), which are of high MW, high viscosity, non-volatile, and have skin moisturizing properties (by reducing the evaporation of water), but it has no deodorizing properties [50]. Therefore, for some types of deodorant creams or cosmetics, it is imperative to add an active substance to the product in order to increase its antioxidant properties and deodorizing activity.

#### *3.5. Antioxidant Properties*

The developed formula (ME + 1% (*w*/*v*) H-CMCH) was selected from former experiments in order to compare the antioxidant activities to the prototype formula (no ME and H-CMCH) as presented in Table 2. The developed formula had strong antioxidant activity. Although the DPPH values of the two formulas were not statistically different (*p* ≥ 0.05), the developed deodorant cream showed the greater ABTS values and had higher ferric ion reducing antioxidant power than the prototype formula.

(*w*/*v*) H-CMCH; heating/cooling cycle for up to 6 cycles.

*3.4. Deodorizing Activity*

**Figure 7.** Total color difference (∆E) of deodorant cream adding (**a**) 0.5%, (**b**) 1.0 %, (**c**) 1.5%, (**d**) 2.0% and (**e**) 2.5% **Figure 7.** Total color difference (∆E) of deodorant cream adding (**a**) 0.5%, (**b**) 1.0 %, (**c**) 1.5%, (**d**) 2.0% and (**e**) 2.5% (*w*/*v*) H-CMCH; heating/cooling cycle for up to 6 cycles.

Trans-2-nonenal is an unsaturated aldehyde produced from lipid oxidation, which

generates an unpleasant greasy odor. It is known to be a major odor component detected from the bodies of old people [20]. Different concentrations (1, 10, and 100 mg/mL) of each

and 1.0% H-CMCH—were used for deodorizing activity against trans-2-nonenal as shown in Figure 8. It was found that the basic deodorant had the lowest deodorizing activity (18–37%). The deodorizing activity was significantly increased (*p* < 0.05) when ME and EGCG were added to the basic formula deodorant. However, the samples of deodorant cream with ME added and formula with EGCG added at a concentration of 1–100 mg/mL. The results showed that the deodorizing activities were in the range of 27–70% and 21–68%, respectively, which was slightly lower than ME and EGCG standards. The basic formula deodorant contains waxes and fatty acids (fatty acids or fatty alcohol),

deodorizing activity.

and EGCG were added to the basic formula deodorant. However, the samples of deodorant cream with ME added and formula with EGCG added at a concentration of 1**–** 100 mg/mL. The results showed that the deodorizing activities were in the range of 27**–** 70% and 21**–**68%, respectively, which was slightly lower than ME and EGCG standards. The basic formula deodorant contains waxes and fatty acids (fatty acids or fatty alcohol), which are of high MW, high viscosity, non-volatile, and have skin moisturizing properties (by reducing the evaporation of water), but it has no deodorizing properties [50]. Therefore, for some types of deodorant creams or cosmetics, it is imperative to add an active substance to the product in order to increase its antioxidant properties and

**Figure 8.** Deodorizing activity of (**a**) ME, (**b**) EGCG, (**c**) prototype cream, (**d**) developed deodorant cream mixed with ME and 1.0% (*w*/*v*) H-CMCH (H2), and (**e**) prototype cream mixed with EGCG and 1.0% (*w*/*v*) H-CMCH at different concentrations (1, 10, and 100 mg/mL). Different lowercase letters (a,b,c...) indicate significant differences between concentrations in the same formula, and different uppercase letters (A,B,C...) indicate significant differences between formulas at the same concentration. *3.5. Antioxidant Properties* The developed formula (ME + 1% (*w*/*v*) H-CMCH) was selected from former **Figure 8.** Deodorizing activity of (**a**) ME, (**b**) EGCG, (**c**) prototype cream, (**d**) developed deodorant cream mixed with ME and 1.0% (*w*/*v*) H-CMCH (H2), and (**e**) prototype cream mixed with EGCG and 1.0% (*w*/*v*) H-CMCH at different concentrations (1, 10, and 100 mg/mL). Different lowercase letters (a,b,c...) indicate significant differences between concentrations in the same formula, and different uppercase letters (A,B,C...) indicate significant differences between formulas at the same concentration.

ME and H-CMCH) as presented in Table 2. The developed formula had strong antioxidant **Table 2.** Antioxidant properties of the developed deodorant cream compared to prototype formula.

experiments in order to compare the antioxidant activities to the prototype formula (no

activity. Although the DPPH values of the two formulas were not statistically different (*p*


Different letters indicate significant different between columns (*p* < 0.05).

#### *3.6. Antibacterial Properties*

For the antibacterial properties, the deodorant cream with the mixture of ME and 1% (*w*/*v*) H-CMCH was compared with a basic formula deodorant cream and streptomycin. It was found that the developed deodorant cream could inhibit all six types of bacteria, including *S. aureus*, *S. epidermidis*, *Corynebacterium* spp., *B. subtilis*, *P. aeruginosa*, and *E. coli*, and it was more effective in antibacterial activity than the basic formula (without ME and H-CMCH), as reflected by a greater inhibition zone (Table 3). Table 3 showed that the incorporation of ME and H-CMCH improved the antimicrobial properties of the deodorant cream. Janardhanan et al. [51] reported that mangosteen pericarp extract is known for its antibacterial activity against several pathogens that cause skin infection and acne. Moreover, He et al. [52] prepared the CMCH/lincomycin hydrogels for investigation into antibacterial properties. The antibacterial activities of the hydrogels were tested against Gram-negative *(E. coli*) and Gram-positive (*S. aureus*) bacteria. The result showed that the CMCH/lincomycin hydrogel was expected to be used as an antibacterial agent. Mohamed and Sabaa [53] studied CMCH/silver nanoparticle (Ag) hydrogels with high antibacterial activity against three Gram-positive bacteria (*S. aureus*, *B. subtilis*, and *Streptococcus faecalis*), three Gram-negative bacteria (*E. coli*, *P. aeruginosa*, and *Neisseria gonorrhoeae*), and *Candida*


*albicans* fungus. The hydrophobicity and antibacterial properties of the solid surface are closely correlated with adhesion forces [54].

**Table 3.** Inhibition zone of prototype deodorant cream and developed deodorant cream.

Different letters indicate significant different between columns (*p* < 0.05).

#### **4. Conclusions**

H-CMCH showed to be an effective polymer in retaining skin moisture for longer than untreated skin, water, propylene glycol, and native chitosan. Additionally, from the mangosteen extract deodorant creams with different H-CMCH concentrations (0.5–2.5% *w*/*v*), the appropriate H-CMCH content was selected from an accelerated stability test with six heating/cooling cycles. For the developed deodorant cream with 1.0% (*w*/*v*) H-CMCH, the viscosity and pH were unchanged after storage in the accelerated state, while the a\* and b\* values of the other formulas were slightly increased and the L\* values was moderately decreased. Therefore, in deodorant cream development, 1.0%(*w*/*v*) H-CMCH was used for the optimal formula. Results indicated that the synergistic activity of ME and H-CMCH in emulsion creams had good potential as an effective skin moisturizing agent enhancer and good deodorizing activity against trans-2-nonenal odor, antioxidant properties, and antibacterial properties. Future studies may include investigation on modeling and numerical simulation of product stability. In addition, the engineering rheological properties of CMCH and creams should also be subsequently investigated.

**Supplementary Materials:** The following are available online at https://www.mdpi.com/article/10 .3390/polym14010178/s1. Figure S1. FT-IR spectra of (**a**) high Mw native chitosan; (**b**) H-CMCH; Figure S2. pH of deodorant creams adding H-CMCH by heating-cooling cycle for up to 6 cycles; Figure S3. Viscosity of deodorant creams adding H-CMCH by heating-cooling cycle for up to 6 cycles; Figure S4. Lightness (L\*) of deodorant creams adding H-CMCH by heating-cooling cycle for up to 6 cycles; Figure S5. Red/green coordinate (a\*) of deodorant creams adding H-CMCH by heatingcooling cycle for up to 6 cycles; Figure S6. Yellow/blue coordinate (b\*) of deodorant creams adding H-CMCH by heating-cooling cycle for up to 6 cycles.

**Author Contributions:** Conceptualization, N.C., P.L. and Y.P.; methodology, N.C., P.R., P.L. and W.R.; formal analysis, N.C., M.J.S. and Y.P.; investigation, N.C. and Y.P.; resources, P.L. and S.R.S.; writing—original draft preparation, N.C. and Y.P.; writing—review and editing, K.J., P.S., N.L. and F.J.B.; supervision, Y.P. and P.L.; funding acquisition, Y.P. and W.P. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the National Research Council of Thailand (NRCT), grant number 256106A1040012, and the APC was funded by Chiang Mai University.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** We wish to thank Center of Excellence in Materials Science and Technology, Chiang Mai University for financial support under the administration of Materials Science Research Center, Faculty of Science, Chiang Mai University. This research work was also partially supported by Chiang Mai University under the Cluster of Agro Bio-Circular-Green.

**Conflicts of Interest:** The authors declare no conflict of interest associated with this research.

#### **References**

