In 2012, the world production of starch was 75 million tons. Maize, cassava, wheat and potato are the main botanical origins for starch production with only minor quantities of rice and other starches being produced. These starches are either used by industry as such or following some conversion. When selecting and developing starches for specific purposes, it is important to consider the differences between starches of varying botanical origin. Here, an overview is given of the production, structure, composition, morphology, swelling, gelatinisation, pasting and retrogradation, paste firmness and clarity and freeze–thaw stability of maize, cassava, wheat, potato and rice starches. Differences in properties are largely defined by differences in amylose and amylopectin structures and contents, granular organisation, presence of lipids, proteins and minerals and starch granule size.
In this paper, the current knowledge on properties of starch blends is critically reviewed. Nowadays, chemical modifications are commonly applied to modify starch properties. However, industry calls for alternatives for chemically modified starches to address the consumer's demand for natural food systems. A simple way to impact starch properties is by blending different starches. In some blends, interactions lead to unexpected gelatinization, pasting, gel texture, and retrogradation properties (non‐additive effect), while an additive effect occurs when the behavior of the blend corresponds to what can be expected based on the individual components. Analysis of different studies describing the physicochemical properties of blends brings insight into the role of botanical origin, amylose content, starch‐to‐water ratio, ratio of starches in the blend, etc. in the behavior of the blends. Gelatinization occurs mostly independently in excess water, while at intermediate water content more non‐additive behavior is recorded. Pasting, rheological, and textural properties show primarily non‐additive effects while retrogradation of starch blends occurs mainly in an additive way. Large differences in granule size and swelling power between the starches in a blend lead to uneven moisture distribution during heating of the starch suspension, which results in a different behavior of the blend than what would be expected based on the behavior of the individual starches.
Blends of starches can undergo additive or non‐additive pasting and gelation. As the impact of this remains undocumented, the effect of (partial) cation removal from waxy rice starch (WRS), regular rice starch (RRS), waxy maize starch (WMS), regular maize starch (RMS), and blends thereof with regular potato starch (RPS) on their pasting and gelation is studied. This is done by prior extraction with water or a solution of singly protonated EDTA. The (partial) removal of cations lowers the gelatinization temperatures of individual starches, causes pasting to start at lower temperatures and the level of viscosity breakdown to increase. This indicates lower granular stability when removing cations. Blends of RPS with untreated WMS/RMS and WRS/RRS show more additive pasting than blends of RPS with the same starches from which cations have been partly removed. Additionally, the presence of cations in cereal starches reduces swelling and viscosity development of RPS. The high peak viscosities, breakdown, and setback values suggest that more granular breakdown results in higher availability of molecules for increased network formation in blends of RPS with treated starches than in those with untreated starches. The obtained results are of interest for food applications where different starches are combined.
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