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- Title
Hydrothermal treatment in organic wheat starch: thermal, structural and pasting properties.
- Authors
Gonçalves de Barros, Wesly; Bet, Camila Delinski; Soltovski de Oliveira, Cristina; Ristow, Nadine; Bisinella, Radla Zabian Bassetto; Schnitzler, Egon; Lacerda, Luiz Gustavo
- Abstract
Introduction. In this investigation, the aim was to study the effects caused by heat moisture-treatment (HMT), low humidity (< 35%) and heating, on organic wheat starch. Materials and methods. Organic wheat starch was submitted to hydrothermal treatment in different concentrations of humidity (10%, 15% and 20%) in an autoclave at 121 °C for 1 hour and 15 minutes. Thermogravimetry (TG), viscoamilographic analysis (RVA), X-ray diffractometry by the powder method (XRD) and scanning electron microscopy (SEM) were performed to compare the properties of native and modified starch. Results and discussion. After heat treatment at low moisture (HMT), the organic wheat starch exhibited greater thermal stability when compared to the untreated. The first mass loss was due the dehydration, followed of stability; the second and third mass loss occurs consecutively with decomposition and oxidation of organic matter, in air atmosphere. Final residues are ashes from starch. Lower pasting temperatures and higher peak viscosity were observed for starch treated with 15 and 20% humidity. Lower retrogradation tendency and viscosity were obtained for organic wheat starch treated with 10% moisture. A decrease in crystallinity was identified for the modified samples, without considerable changing in the diffraction pattern. The main diffraction angles were registered at 15, 17, 18 and 23°, in 2 (?), with low intensity. This behaviour is characteristic of type A diffraction pattern starch (typical of cereals). By Scanning Electron Microscopy (SEM), the organic wheat starch presented a bimodal distribution without major changes in the morphology of the granules. After HMT starch granules showed a slight increase in the average diameter; 17.9 to 27.7 μm in the major granules (A) and 5.6 to 7.1 μm in the minor granules (B). The shape in (A) is oval and in (B) is lenticular. Some depressions in surface of starches are observed mainly after HMT, which can be due the starch-protein interactions. Conclusions Some properties were affected after modification by HMT. The decrease in pasting temperature and major thermal stability and viscosity were obtained.
- Subjects
WHEAT starch; DIFFRACTION patterns; SCANNING electron microscopy; STARCH; THERMAL stability; HEAT treatment
- Publication
Ukrainian Journal of Food Science, 2020, Vol 8, Issue 2, p195
- ISSN
2310-1008
- Publication type
Article
- DOI
10.24263/2310-1008-2020-8-2-3