Functional and dynamic rheological properties of acetylated starches from two cultivars of cassava

Abstract

The starches derived from two different cultivars of cassava were modified with acetic anhydride. The increase in swelling power and solubility of the cassava starch (CS) pastes treated with different acetic anhydride concentration could be attributed to easier hydration, resulting from reduction of interaction between starch chains due to the substitution. The transition temperatures (T o , T p and T c ) and enthalpy of gelatinisation (DH) of acetylated CS, were determined. The values were lower than those of native starches. Rheological properties of CS pastes (5% w/w) as a function of the degree of substitution were evaluated in dynamic shear force measurements. Magnitude of storage modulus (G 0 ), loss modulus (G 00 ) and complex viscosity (Eta à ) of acetylated CS pastes were determined also. Dynamic moduli (G 0 , G 00 and Eta à ) values of acetylated sweet cultivar pastes were generally higher than those of native starch whereas the acetylated samples of the bitter cultivar were lower than those of native starch. The magnitudes of G 0 were greater than those of G 00 and Eta à at all frequencies (v). The fact that all the tan d (ratio G 00 /G 0 ) values (0.7-0.48 and 0.25-0.44) were less than one is an indication that the samples are more elastic than viscous. The acetylated starches could find promising industrial uses in food products like Lemon curd and Mayonnaise and other non-food applications.

Recent trend in the physical and chemical modification of starches from different botanical sources: A review

“…The acetylation reactions are typically carried out in water, though organic solvents also have been shown to be effective . Ac starch is a starch ester that has been extensively studied over the last two decades . Introduction of acetyl groups reduces the bond strength between starch molecules causing an increase in the swelling power and solubility of the modified starch.…”

Composition, structure, physicochemical properties, and modifications of cassava starch

“…The acetylation increased the water solubility and paste clarity, decreased the 850 pasting viscosities and gelling ability, the glass transition and gelatinization temperatures, and851 improved the freeze-thaw stability(Aiyeleye, Akingbala, & Oguntimein, 1993; Agboola, 852 Akingbala, & Oguntimein, 1991a & 1991b;Moorthy, 1985;Osunsami et al, 1989). Dynamic 853 moduli (G' and G'') of starch paste (5%) were higher or lower than control, depending on the 854 specific starch genotypes used(Osundahunsi & Mueller, 2011). Gels (30 and 40% moisture 855 content) of acetylated starch had lower amounts of freezable water than control(Tran, 856 Thitipraphunkul, Piyachomkwan,& Sriroth, 2008).…”

Efeito da acidificação nas propriedades físico-químicas e funcionais do amido de sementes de manga (Mangifera indica L.), variedade Tommy Atkins

“…Os mesmos autores destacam, ainda, que o baixo PI pode ser atribuído à presença de lipídeos no amido, que formam complexo com a amilose. Osundahunsi & Mueller (2011), pesquisando propriedades de amido de duas variedades de mandioca, encontraram amidos nativos com PI de 21,3 e 29,6 g/g. No entanto, Adebowale et al (2005) encontraram, para o amido de fruta-pão, PI de 6,40 g/g a 80 o C. Tem sido reportado que o PI depende da capacidade de retenção de água das moléculas de amido por pontes de hidrogênio.…”

“…Bello-Pérez et al (2006), analisando amido de pinhão, observaram que sua solubilidade aumentava conforme a temperatura, com variação de 5 a 20%. Já Osundahunsi & Mueller (2011) obtiveram 3,34% de solubilidade para o amido nativo de mandioca. Isto ocorre porque durante o processo de acidificação, os íons hidroxônios (H 3 O + ) ligam-se aos átomos de oxigênio das ligações glicosídicas, hidrolisando essas ligações.…”