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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]

Abstract Sweet potato is an important starch resource and has different colored root tubers due to different genotype backgrounds. However, it is unclear whether starch properties are related to the color of root tuber. In this study, 3 white, 3 yellow, and 3 purple sweet potato varieties were planted in the same environment. The dry root tubers of white varieties had the highest starch ranging from 61.5 to 67.5% and the lowest soluble sugar ranging from 13.1 to 18.0%, and those of yellow varieties had the lowest starch ranging from 45.8 to 53.1% and the highest soluble sugar ranging from 28.9 to 31.5%. Starches from different varieties had different granule sizes (D[4,3] 12.3–18.1 μm) and amylose contents (24.1–27.2%), but all exhibited C A -type crystalline structure. The relative crystallinity ranged from 22.3 to 25.5%, and the IR absorbance ratios of 1045/1022 and 1022/995 cm−1 ranged from 0.665 to 0.775 and from 0.846 to 0.944, respectively, among 9 varieties. The starches from the same or different colored varieties had differences in swelling power, water solubility, gelatinization temperature, pasting viscosity, and digestion properties. The cluster analysis based on starch property parameters indicated that starch properties of sweet potato had no relationship with the color of root tuber but were determined by the genotype background of variety. Graphical abstract Image 1 Highlights • Starch properties were measured in 3 white, 3 yellow and 3 purple sweet potatoes. • The white and yellow varieties contained the highest and lowest starch, respectively. • The starches from the same or different colored varieties had different properties. • The cluster analysis of different colored varieties was based on starch properties. • Characteristics of starch had no relationship with the color of root tuber. [ABSTRACT FROM AUTHOR]

Abstract The extra-long chain (ELC) of amylopectin influences molecular compositions of starch. In this study, starches were isolated from 22 rice varieties with different ELCs. Molecular compositions of starch were determined, and their relationships with crystalline structure, gelatinization properties, pasting properties, and enzyme hydrolysis were analysed. The results showed that the starches with different ELCs had significantly different structural and functional properties. The ELC was significantly positively related to setback viscosity and negatively related to relative crystallinity, lamellar peak intensity, swelling power, gelatinization enthalpy, and rapidly digestible starch of retrograded starch. The true amylose content was significantly positively related to retrogradation and negatively related to peak viscosity and hydrolysis degree by α-amylase and amyloglucosidase. The short branch-chain of amylopectin was significantly positively related to lamellar peak intensity, swelling power, hydrolysis degree by α-amylase, and rapidly digestible starch of retrograded starch and negatively related to setback viscosity and resistant starch of retrograded starch. The ratio of short to long branch-chain of amylopectin was significantly positively related to swelling power and hydrolysis degree by α-amylase. The principal component analysis and partial least squares discriminant analysis demonstrated that the low-ELC starches were distinguished from the middle- and high-ELC starches, the middle-ELC starches basically clustered together, but the high-ELC starches were highly dispersed. The above results would provide some new information for rice quality breeding and starch applications by changing the ELC in starch. Graphical abstract Image 1 Highlights • Starches from 22 rice varieties had different extra-long chains (ELC) of amylopectin. • GPC profiles of debranched starch and amylopectin measured molecular compositions. • Gelatinization and pasting properties and enzyme hydrolysis of starch were measured. • PLSR showed interrelationship between molecular compositions and starch properties. • PCA and PLS-DA revealed the differences among rice varieties with different ELCs. [ABSTRACT FROM AUTHOR]

Starch was isolated from the kernels of jackfruit, longan, loquat, litchi, and mango fruits, which contained approximately 56, 59, 71, 53, and 64% starch, respectively, indicating that these fruit kernels are good starch sources. The structural and functional properties of these isolated starches were investigated and compared. The starches had irregular, truncated, spherical, and elliptical shapes with central hila and exhibited different sizes, with mango starch being the largest and jackfruit and longan starches being the smallest. The five starches had similar amylose contents but exhibited significantly different crystalline properties including crystalline type, relative crystallinity, short-range ordered structure, and lamellar intensity. Among the five starches, the jackfruit and loquat starches had the highest and lowest gelatinization temperature and enthalpy, respectively, and the litchi and mango starches had the highest and lowest pasting viscosity, respectively. The longan and loquat starches were more susceptible to enzyme hydrolysis than the other starches. [ABSTRACT FROM AUTHOR]

Chinese yam is an important edible starch plant and widely cultivated in China. Its rhizome and bulbil are starch storage tissues below and above ground, respectively. In this paper, starches were isolated from the rhizome and bulbil of Chinese yam, and their structural and functional properties were compared. Both starches had an oval shape with an eccentric hilum and a CA-type crystalline structure. Their short-range ordered structure and lamellar structure had no significant difference. However, the rhizome starch had a significantly bigger granule size and lower amylose content than the bulbil starch. The swelling power and water solubility were significantly lower in the rhizome starch than in the bulbil starch. The onset and peak gelatinization temperatures were significantly higher in the rhizome starch than in the bulbil starch. The rhizome starch had a significantly higher breakdown viscosity and a lower setback viscosity than the bulbil starch. The thermal stability was lower in the rhizome starch than in the bulbil starch. The rhizome starch had a significantly lower resistance to hydrolysis and in vitro digestion than the bulbil starch. The above results provide important information for the utilization of rhizome and bulbil starches of Chinese yam. [ABSTRACT FROM AUTHOR]

The multi-scale structural dynamics of amylopectin-only barley starch (APBS), normal barley starch (NBS), and amylose-only barley starch (AMBS) digested with amylolytic enzymes for 120 min were investigated in this study. For all starches, 0–20 min was identified as a rapid digestion stage, followed by a 20–120 min slow digestion. For APBS and NBS, the content of short chains (DP ≤ 12) and the thickness of crystalline and amorphous nano-lamellae increased, whereas the crystallinity decreased, and pores were generated on the granular surface during the rapid digestion stage. At the following slow digestion stage, the branching degree and relative amount of double helices increased, the crystalline and lamellar structures were lost, and the hydrolyzed starch segments aggregated. For AMBS, the rapid digestion stage was characterized by an increased content of short chains (DP ≤ 8) and B-type crystals and decreased amounts of V-type crystals. Furthermore, the lamellar and granular structures were lost, and digestion residues aggregated during the first stage of AMBS, which were formed in the second digestion stage of APBS and NBS. The second slow digestion stage of AMBS was characterized by an increased branching degree and a decreased relative content of single helices. It is suggested that the aggregated digestion residues at the initial digestion stage are the main reason for the overall low digestibility of AMBS. [Display omitted] • Amylose barley starch (AMBS) lost granular structure at initial digestion stage. • AMBS reorganized immediately and was thereafter hydrolytic resistant. • Single helices and the V-type crystals decreased in AMBS upon hydrolysis. • Amylopectin barley starch (APBS) first generated pores and then reorganized. • APBS had a high content of double helices after digestion. [ABSTRACT FROM AUTHOR]

We investigated the effects of drought stress (DS) on maize varieties with different amylose content (AC). In starches with AC of 33 %, DS increased the contents of amylopectin (AP) chains with a degree of polymerization (DP) > 36 and decreased the AP chains with DP ≤ 36, while the AC was unchanged. DS decreased the crystallinity, the thickness of both amorphous and crystalline lamellae, and average granular size. In contrast, the digestibility increased. For starches with AC of 45 %, DS increased the content of AP chains with DP > 24 and AC, while the contents of AP chains with DP ≤ 24 decreased. DS produced starch with thinner crystalline lamellae, thicker amorphous lamellae, more elongated and larger granules. The digestibility of the starches decreased. In starches with AC of 53 %, moderate DS led to similar structural and functional changes as found for starches with AC of 45 %. Finally, severe DS resulted in the decrease of AC. [Display omitted] [ABSTRACT FROM AUTHOR]