nucleic acids, and amide I and amide II of the proteins present in the mucilage. Absorption bands between 1,650 and 1,444 cm-1 are typical of symmetric elongation of carboxylic groups of uronic and galacturonic acid residues (23,25). In 1,244 cm-1, the molecular groupings are of amines and amides (26) of the acetyl group belonging to amino sugars. Between 1,200 and 800 cm-1 is the region that represents the fi ngerprint of the arabino- galactan macromolecule (23,25,27,28), also present in TM. Proximal composition, yield, and physicochemical properties of mucilage. The proximal composition, yield in mucilage, EC and activity, emulsifying stability, and pH of emulsions are shown in Table 2. The yield in mucilage was 8.83%, and the mineral residue content (ash) was 8.50%, with a highlight on the content of potassium and phos- phorus (Table 2). These results are close to those found by Andrade, Nunes, and Pereira (2). The carbohydrate and crude protein contents were 62.42 and 21.19%, respectively, and these values are close to those reported by Njintang et al. (12). The pH of the mucilage was slightly acidic, with a value of around 5.91. The EA and stability of the emulsion (SE) presented values of 5 5 and 80%, respec- tively. Lima Junior et al. (29) studied the EA of Ora-pro-nóbis and found values of 83%. Wu et al. (30), when studying the galactomannans of different gums, found values for EA and ES ranging from 40% to 80%. In the case of the EA of TM, the values are within the range found by these authors, and the high value calculated for ES may have occurred due to the presence of starch in the mucilage, as shown by the XRD analysis. The starch could be gelatinized as the beginning of this phenomenon occurs at 12.7° C and increases the viscosity at 77° C (9), and may have contributed to the stability of the emulsion. Figure 3. Colocasia esculenta MC mucilage thermogram. JOURNAL OF COSMETIC SCIENCE 286

The mucilage of taro showed a high EC (1,172.2 g of emulsifi ed oil per gram of protein), and this is mainly due to the presence of carbohydrates and proteins in high concentrations. According to Andrade et al. (2), the emulsifying property of the mucilage of Colocasia esculenta is related to the chemical composition, due to the presence of carbohydrates rep- resenting the hydrophilic part and the presence of proteins that are the hydrophobic part, which are part of the macro molecule AGP, which can be confi rmed in the FTIR spectrum by the presence of bands which represent AGP’s fi ngerprint. STABILITY STUDY The stability of semisolid emulsions prepared with mucilage of Col ocasia esculenta (F2, F3 e F4) and xanthan gum (F1) was evaluated by comparing pH, density, viscosity, consistency index, and fl ow behavior index (initial and fi nal) after six cycles of thermal stress (Table 3). A small reduction in the pH values was observed with the increase of the mucilage content in the formulations (Table 3). This behavior is possibly associated with the slightly acidic pH (5.91) of TM, whose content increased from formulation F2 to F4. Similarly, after the thermal stress cycles, there was also a small reduction in pH, and this is possibly related to stabilization reac- tions inherent in complex mixtures such as cosmetic creams, which are formulated with different ingredients. It should be noted that this fact did not infl uence the acceptable characteristics of the product, since the pH remained close to the pH of human skin, which is around 5.5 (31). Figure 4. Fourier transform infrared spectroscopy (FTIR) for TM. TARO MUCILAGE IN COSMETIC FORMULATIONS 287