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Raw starch is commonly modified to enhance its functionality for industrial applications. There is increasing demand for 'green' modified starches from both end-consumers and producers. It is well known that environmental conditions are key factors that determine plant growth and yield. An increasing number of studies suggest growth conditions can expand affect starch structure and functionality. In this review, we summarized how water, heat, high nitrogen, salinity, shading, CO 2 stress affect starch biosynthesis and physicochemical properties. We define these treatments as a fifth type of starch modification method - agricultural modification - in addition to chemical, physical, enzymatic and genetic methods. In general, water stress decreases peak viscosity and gelatinization enthalpy of starch, and high temperature stress increases starch gelatinization enthalpy and temperature. High nitrogen increases total starch content and regulates starch viscosity. Salinity stress mainly regulates starch and amylose content, both of which are genotype-dependent. Shading stress and CO 2 stress can both increase starch granule size, but these have different effects on amylose content and amylopectin structure. Compared with other modification methods, agricultural modification has the advantage of operating at a large scale and a low cost and can help meet the ever-rising market of clean-label foods and ingredients. [ABSTRACT FROM AUTHOR]

The nitrogen (N) influences the growth of sweet potato. However, it is unclear whether the different levels of N can affect starch physicochemical properties. In this study, 9 different colored-fleshed sweet potato varieties were planted in the same field with additional N fertilizer treatment of 0, 15 and 30 kg/ha. The physicochemical properties of starches from root tubers were measured. With increasing N level, the amylose content decreased in yellow-fleshed variety Sushu 16 and increased in white-fleshed variety Sushu 29 and purple-fleshed varieties Ningzishu 1 and 4, but did not significantly change in other varieties. The starch size decreased in purple-fleshed variety Ningzishu 1 and white-fleshed varieties Sushu 28 and Sushu 29 with increasing N treatment, but first increased then decreased in yellow-fleshed variety Sushu 16 and first decreased then increased in white-fleshed variety Sushu 24 and yellow-fleshed variety Sushu 25. The different levels of N treatment had no influence on protein content, crystalline structure, and gelatinization enthalpy of starch. The effects of N treatment on gelatinization temperatures and pasting viscosities of starches were determined by varieties and genotype backgrounds of sweet potato. The PLSR and PLS-DA were also carried out based on structural, thermal, and pasting parameters of starches. • Different colored-fleshed sweet potato varieties grew with different levels of N. • Amylose content and granule size of starch responded to N treatment differently. • N levels had no effects on protein content, crystallininity, and enthalpy of starch. • Thermal and pasting properties of starch were correlated with genotype backgrounds. • Structural and functional properties of starches were analyzed with PLSR and PLS-DA. [ABSTRACT FROM AUTHOR]

In this study, 6 very small granule starches (VSGSs) were isolated from endosperms of dicotyledon Amaranthus cruentus , Agriophyllum squarrosum , Chenopodium quinoa , Euryale ferox , Mirabilis jalapa , and Vaccaria hispanica. Their morphologies and physicochemical properties were investigated. Most VSGSs with granule size <3 μm were spherical or polygonal, and their apparent amylose contents ranged from 19.4 to 33.1% with A. cruentus starch the lowest and E. ferox starch the highest. All VSGSs had the same A-type crystalline structure with relative crystallinities from 23.3 to 29.6%. Though 6 VSGSs had slight differences in short-range ordered structure and lamellar repeat distance, their lamellar peak intensities exhibited significant differences. The gelatinization temperatures showed significant differences among 6 VSGSs with C. quinoa starch the lowest and M. jalapa starch the highest. The 6 VSGSs had significantly different pasting viscosities with peak viscosities from 1887 to 4579 mPa s, hot viscosities from 1704 to 3479 mPa s, breakdown viscosities from 56 to 1170 mPa s, final viscosities from 2419 to 4811 mPa s, and setback viscosities from 715 to 1821 mPa s. The digestion properties of starches were significantly different among 6 VSGSs. The above results could provide some references for applications of these VSGSs. • Very small granule starches (VSGSs) were isolated from dicotyledon endosperms. • Most VSGSs had spherical or polygonal shape with granule diameters <3 μm. • Six VSGSs had amylose contents from 19.4 to 33.1% and the same A-type crystallinity. • Six VSGSs had significantly different lamellar peak intensity and thermal properties. • Six VSGSs exhibited significantly different pasting and digestion properties. [ABSTRACT FROM AUTHOR]