**3.1.1 High Resolution Optical Microscopy- HROM**

Samples were spread on glass sheets to be observed with optical microscope (Nikon Eclipse 80i, Japan) coupled to digital camera (Nikon DS-2MV 2Mp, Japan), through the bright field technique.

Photomicrographs of cassava flour in Figure 1 were captured with 10x (down) and 40x (up) objectives; in them may be observed longitudinal and amorphous fibers, and round /truncated starch granules.

Fibers, stained blue-violet because dye used (toluidine blue), it were longitudinally elongated and not elongated amorphous. As shown in Figure 1, there is a greater number of starch granules by number of fiber (s) found in each catch, this is because the fiber content in the flours studied is very low, between 1.7 and 2.7% in wet basis, compared with the starch content, between 75 and 85% wet basis, according to proximate analysis results (not shown).

Thermoplastic Cassava Flour 29

Samples were analyzed between 2θ = 2° and 2θ = 35 °, in an X-ray diffractometer (Rigaku 2002, Japan), (wavelength = 0.15405 nm) at 40 kV and 30 mA. The scanning speed was 5°C/min.

Fig. 2. SEM microphotographs cassava flour

Fig. 3. X-Ray Diffractogram cassava flour

**3.1.3 X-Ray diffaction** 

Moorthy, 2002, reported that the fiber content of cassava flour is usually between 2-3% and starch content accounts for 84% (Rodriguez et al., 2008). A recent study on cassava roots (Teerawanichpan et al., 2008) discusses the anatomy by light microscopy using toluidine blue and shows four types of tissues, sclerenchyma, parenchyma, secondary and primary xylem. Starch granules have spherical and semi-spherical forms, as reported by other studies of cassava starch morphology (Alvis et al., 2008) - some of them truncated features shown as flat surfaces on one or more sides of the granule.

Fig. 1. HROM microphotographs cassava flour

### **3.1.2 Scanning Electron Microscopy- SEM**

The samples were spread out on cylindrical specimens with carbon tape and subjected to gold bath (JEOL JSM-6490) for 200 seconds with a gap of 40-60 mTorr.

Figure 2 shows starch granules of variable diameter that does not exceed 25μm, and truncated spherical shapes typical of cassava starch. Fractures were also observed in its structure, possibly by the effects of grinding, especially when you consider that the particles are broken because the process to reduce particle size at the beginning of the characterization process of raw material.

Moorthy, 2002, reported that the fiber content of cassava flour is usually between 2-3% and starch content accounts for 84% (Rodriguez et al., 2008). A recent study on cassava roots (Teerawanichpan et al., 2008) discusses the anatomy by light microscopy using toluidine blue and shows four types of tissues, sclerenchyma, parenchyma, secondary and primary xylem. Starch granules have spherical and semi-spherical forms, as reported by other studies of cassava starch morphology (Alvis et al., 2008) - some of them truncated features

The samples were spread out on cylindrical specimens with carbon tape and subjected to

Figure 2 shows starch granules of variable diameter that does not exceed 25μm, and truncated spherical shapes typical of cassava starch. Fractures were also observed in its structure, possibly by the effects of grinding, especially when you consider that the particles are broken because the process to reduce particle size at the beginning of the

gold bath (JEOL JSM-6490) for 200 seconds with a gap of 40-60 mTorr.

shown as flat surfaces on one or more sides of the granule.

Fig. 1. HROM microphotographs cassava flour

**3.1.2 Scanning Electron Microscopy- SEM** 

characterization process of raw material.

Fig. 2. SEM microphotographs cassava flour

### **3.1.3 X-Ray diffaction**

Samples were analyzed between 2θ = 2° and 2θ = 35 °, in an X-ray diffractometer (Rigaku 2002, Japan), (wavelength = 0.15405 nm) at 40 kV and 30 mA. The scanning speed was 5°C/min.

Fig. 3. X-Ray Diffractogram cassava flour

Thermoplastic Cassava Flour 31

Fig. 4. Response surface of TPCF material with particle size 250 µm

Fig. 5. Response surface of TPCF material with particle size 600 µm

The samples showed a peak at 2θ: 20°, which according to Zobel (1988, quoted in Singh, 2006), is attributed to the presence of amylose-lipid complexes in starches, whose intensity could be related to the proportion of them. There were strong peaks at 2θ: 15°, 2θ: 17°, 2θ: 18° and 2θ: 23°, characteristic of type A pattern (Van Soest et al., 1996; Cheetham & Tao , 1998; Rodriguez et al., 2007; Leblanc et al. 2008; Perdomo et al, 2009), which indicates that the crystalline arrangement is monocyclic.
