Native starches pasting properties

The dispersion of low-substituted, acetylated starches in water increased as the number of acetate groups was increased and as the temperature was raised. The viscosity of starch-acetate pastes was lower than that of native starch pastes at all temperatures. The viscosity decreased until an acetyl content of 2.36% was reached, after which it changed only slightly. The reduced ability of starch acetates to form gels could be expressed in terms of the ratio of the viscosities at low and high temperatures. A rotation viscosimeter Rheotest was used to study the viscosities and the rheological properties of starch acetates. 

Compared to native starches, monophosphate esters have a decreased gelatinization temperature range and swell in cold water at a DS of 0.07. Starch phosphates have increased paste viscosity and clarity and decreased retrogradation. Their properties are in many ways similar to those of potato starch, which naturally contains phosphate groups. 

Paste properties of native starches from different botanical origins have been reviewed.92,133 Relevant to practical usage of starch, the most important paste properties are viscosity, texture, paste transparency, resistance to shear and tendency to retrograde. In terms of texture, the translucent potato starch pastes can be described as cohesive, long-bodied, stringy and rubbery. Other root, tuber and waxy starches give pastes of similar texture to that of potato starch, but are generally less cohesive. On the other hand, pastes from common cereal starches are opaque and can be described as noncohesive and short- and heavy-bodied. These and other properties of several native starches are summarized in Table 8.1. 

Starch functionality in food systems is primarily related to its gelatinization, retrogradation, and pasting properties. The functionality of native starch varies with botanical somce, amylopectin fine structure, and amyloseiamylopectin ratio. 

Starch pastes may be dried to films, especially for nonfood applications, such as adhesives and coatings for paper sheets or textile fibers. The desired technical properties are plasticity, strength, water solubility, response to humidity, transparency and gloss. They result from the type of paste texture, clarity and gelling, which arc consequences of amy-lose-amylopectin interactions. Only starches from waxy com, potato or other root and tuber crops exhibit the desired properties, wdiereas native cereal starches are not so well suited in this respect because of their short texture and rapid setting to gels, which favors insolubility, turbidity and brittleness. Drawbacks of most native starches are ... 

Chaisawang, M., Suphantharika, M. (2006). Pasting and rheological properties of native and anionic tapioca starches as modified by guar gum and xanthan gum. Food Hydrocoil., 20, 641-649. 

Compared to native wheat starch, the sodium starch 1-octenylsuccinate derivative gives much higher peak and cold-paste viscosities, but with considerably reduced paste viscosity during the cooking cycle.27 This product also exhibits emulsifying properties. When the 1-octenylsuccinate derivative is complexed with aluminum ion, a modified wheat starch that flows freely when dry and resists wetting by water... 

Heat-moisture treated starch, sometimes called Tao starch in Thailand, is prepared from cassava starch by heating moistened starch (—50% moisture content) at various temperatures and times. Heat-moisture treatment provides a modified starch that produces a less cohesive, shorter-textured paste with improved shear resistance and gel properties, as compared to the long, stringy, cohesive paste of native tapioca starch. 

Starch succinates and, to a higher degree, octenyl succinates have, due to their hydrophobic groups, surface-active properties. They are used for preparation of emulsions and for encapsulation of lipophilic substances. Additionally, starches with poor water-binding capacity and low paste viscosity in the native state, like triticeae starches are upgraded by succinylation to highly stable pastes. Lit. Van Beynum/Roels 91-93, (1985)... 

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