Starch pastes and gels

Hydroxyethyl group introduction at low DS results in distinct modification of physical properties. Among these are decreased gelatinization temperature range (126), increased granule swelling rate (127), and decreased abiUty of starch pastes to gel and retrograde. 

Takahashi, S., and Seib, P. A. (1988). Paste and gel properties of prime corn and wheat starches with and without lipids. Cereal Chem. 65 474-483. 

Tecante, A. Doublier, J.L. (1999). Steady flow and viscoelastic behaviour of crosslinked waxy corn starch-K-carrageenan pastes and gels. Carbohydrate Polymers, Vol. 40, No. 3, pp. 221-231, ISSN 0144-8617. 

Techawipharat, J., Suphantharika, M. BeMiller, J. (2008). Effects of cellulose derivatives and carrageenans on the pasting, paste, and gel properties of rice starches. Carbdiydrate Polymers, Vol. 73, No. 3, pp. 417-426, ISSN 0144-8617. 

In a current rheological study [296], the galactoxyloglucan from Hymenia courbaril was mixed with starch containing 66% amylose and with waxy corn starch (amylopectin). The gel mixtures showed, under static rheological conditions, an increase in paste viscosity compared to those of the polysaccharides alone. Dynamic rheometry indicated that the interactions resulted in increased thermal stability of the gel formed in comparison to that of the starch alone. 

Species and/or cultivar differences are also observed in other starch properties and in the properties of isolated amylose and amylopectin. To illustrate, purified amylose samples have been shown to differ in (3-amylolysis limit and average DP.64,67,124 Purified amylopectin samples have also been shown to differ in (3-amylolysis limit, average length of unit chains and viscosity.64,66 67 124,125 Campbell et al.121 observed a range of amylose content from 22.5% to 28.1% in 26 maize inbreds selected for maturity, kernel characteristics and pedigree. Starches from these non-mutant genotypes also differed in thermal properties (DSC), paste viscosities and gel strengths. 

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