Effect of the Alkaline Treatment on the Ultrastructure of C-Type Starch Granules

Abstract

The effect of alkaline treatment on the ultrastructure of C-type starch granules was investigated during the alkaline extraction of Araucaria angustifolia (pinhao) starch. The efficiency in protein removal was evaluated using intrinsic fluorescence and Kjeldahl's method. In parallel, morphological changes of starch granules were observed using scanning electron microscopy and atomic force microscopy. The starch crystallinity was monitored by wide-angle X-ray scattering and the lamellar structure was studied by small-angle X-ray scattering (SAXS). The paracrystalline model was employed to interpret the SAXS curves. It was found that the granular organization was significantly altered when alkaline solutions were used during the extraction. A partial degradation of B-type allomorph of starch and a significant compression of semicrystalline growth rings were observed.

On the lamellar width distributions of starch

“…The granules size typically ranges from 6 to 21 lm while exhibits a distribution centered at 12.5 lm (Fig. 2D) (Bello-Perez et al, 2006;Thys et al, 2008). The polydispersity index of pinhão starch distribution (20.8%) is significantly smaller than those obtained for normal maize starch indicating a regulated granule size synthesis.…”

“…Both maize starches were used as received. Pinhão starch was obtained from seeds of Araucaria angustifolia and isolated through successive washes with water (Thys et al, 2008). The efficiency of starch isolation was verified using fluorescence spectroscopy (Cardoso, Putaux, Samios, & da Silveira, 2007;Cardoso, Samios, & Silveira, 2006).…”

“…WAXD profiles were obtained by radial averaging and normalized to the integrated area covering a scattering vector q (q = (4p/k) sinh; 2h = scattering angle) ranging from 2.4 to 28.0 nm À1 . The WAXD patterns were used to determine the crystallinity and respective amount of A-and B-type allomorphs as described in the literature (Thys et al, 2008).…”

Effect of alkali-treatment on physicochemical, pasting, thermal, morphological and structural properties of Horse Chestnut (Aesculus indica) starch

“…Upon treatment with 0.25 % NaOH, the smooth surface presented grooves after 10 days of modification and many granules appeared to be adhered to each other. The adhesion of the granules after alkali treatment could be caused by leached amylose selfassociating to form an amorphous polymer network with neighbouring granules [21]. When starches were treated with 0.5 % NaOH, the starch granules showed surface cracking which increased with modification from 0 to 10 days.…”

Uso De Diferentes Plastificantes Na Produção De Biofilmes À Base De Amido De Pinhão

“…Uma alternativa de aplicação do pinhão pode ser a utilização do amido presente em grande quantidade nesta semente e já estudado anteriormente (Bello-Pérez et al, 2006;Thys et al, 2008;Thys et al, 2010;Spada et al, 2012;Daudt et al, 2014) como base para a produção de biofilmes comestíveis. Os filmes utilizados atualmente são embalagens plásticas provenientes de derivados de petróleo, que podem acarretar vários problemas ambientais por não serem biodegradáveis em curto prazo (Sorrentino et al, 2007).…”