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| Author(s): |
Luis Fernando Polesi
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Piracicaba. |
| Institution: | Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) |
| Defense date: | 2009-08-28 |
| Examining board members: |
Silene Bruder Silveira Sarmento;
Maria Antonia Calori Domingues;
Célia Maria Landi Franco
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| Advisor: | Silene Bruder Silveira Sarmento |
| Abstract | |
Resistant starch (RS) is the fraction of starch that does not suffer the action of digestive enzymes, showing similar behavior to that of dietary fiber. The aim of this study was to evaluate the amounts and characteristics of RS obtained from chick-pea and high amylose pea starches using different processes of molecular weight reduction. The natural or pregelatinized starches were submitted to acid (2 M HCl for 2.5 h) or enzymatic (pullulanase, 40 U / g per 10 h) hydrolysis prior to a control process, which consisted of hydrothermal treatment (autoclaving at 121 ° C for 30 min), refrigeration (4 ° C for 24 h) and liophilization. The material was characterized as to the general appearance by scanning electron microscopy (SEM), RS content, total dietary fiber (TDF) content, water absorption index (WAI), water solubility index (WSI), crystallinity pattern (X-ray diffraction), viscosity (RVA - Rapid Visco Analyzer) and thermal properties (DSC - Differential Scanning Calorimeter). The RS content in pea and chick-pea natural starch was 39.8 and 31.9%, respectively. The processed starches showed contents ranging from 38.5 to 54.6% for pea and from 16.4 to 32.3% for chick-pea starch. The best treatments to raise the level of RS were the acid treatment (natural and gelatinized starch) for pea and the enzymic treatment (gelatinized starch) for chick-pea starch. The FDT amounts in processed pea starches ranged from 22.9 to 37.1% and were higher than those of chick-pea, which ranged between 7.2 and 15.7%. The photomicrographs in SEM revealed the presence of whole grains (not fragmented) in pea starches treatments, while the treated chick-pea starches showed only amorphous mass, without the evidence of granules. The cristallinity patterns of natural starches were B and C types, respectively for pea and chick-pea starch. Both processed starches, however, presented B type pattern. The natural starches showed endotherms between 56 and 90°C, while the processed starches showed endotherms at higher temperatures (131 and 171°C). The processed pea starches gelatinizati on enthalpy (H) was higher than those of processed chick-pea starches. The natural and processed pea starches, in general, showed low viscosity (<20 RVU) in RVA. The natural chick-pea starch presented viscoamylogram well defined, typical of this botanical source. The resistant starches obtained by hydrolysis showed in both sources, a decrease in viscosity compared to the control treatment. The viscosity was inversely proportional to the RS content in the samples. The hydrolysis and the thermal processing promoted an increase in WAI and WSI of treated starches. The hydrolysis process of pea and chickpea starches may raise the level of RS when compared to the control process. (AU) | |