Strategies for starch customization: Agricultural modification

Influence of Elevated Potassium Fertilization on Structural and Functional Properties of Sweet Potato Root Tuber Starch

Nine sweet potato varieties with different flesh colors were cultivated under uniform environmental conditions with potassium (K) fertilizer treatments at levels of 0, 22.5, and 45 kg/ha. The structural and functional properties of the starches were subsequently analyzed. The soluble sugar content in the dry root tuber increased, with higher K levels in most varieties. Amylose content decreased in Sushu16 but increased in Ningzishu1, with no significant differences observed in other varieties across different K levels. Elevated K levels had no effect on starch protein content, crystalline type, or gelatinization enthalpy. The impact of K fertilizer on starch thermal and pasting properties varied among the varieties. PLSR and PLS-DA analyses revealed that genotype background was the primary factor influencing starch properties. This research will provide a reference for the improvement of sweet potato production quality and efficiency and a scientific basis for the cultivation and utilization of sweet potato root tubers.

Sulfur affects multi-scale starch structures and its contribution to the cookie-baking quality of wheat subjected to shade stress

The components and structure of starch macromolecules critically determine its food-use properties. However, elemental sulfur supplementation affects the relationship between starch structure and the cookie-making quality of wheat under shaded environments remains unclear. Here, we investigated the effect of sulfur on the starch multi-scale structures and its contribution to the cookie-baking quality of wheat after pre- or post-anthesis shading. Compared with the unshaded control, shade stress decreased the amylose and total starch contents, formed smaller B-type starch granules, narrowed the molecular weight distribution, and decreased the amylopectin long-chain proportion, crystallinity, viscosity, and spread ratio of cookies. Weak-gluten cultivars are more sensitive to shade stress than strong-gluten cultivars. Under shaded environments, sulfur increased the amylopectin content, proportion of amylopectin short chains, and total starch content, increasing the mean diameter of starch granules and viscosity, ultimately decreasing the cookie hardness. The random forest model revealed that the surface area of the starch granules (18.7 %) and amylopectin B3 chain (6.7 %) contributed the most to the variation in the cookie spread ratio. Cookie hardness was determined mainly by the total starch (7.8 %), amylopectin (6.3 %), and trough viscosity (5.0 %). Our results help to design strategies for achieving superior-quality wheat in the context of global dimming.

Preparation and characterization of starch carbamate modified natural sodium alginate composite hydrogel blend formulation and its application for slow-release fertilizer

The exploration of environmentally friendly slow-release fertilizer (SRF) based on natural bio-polymers is of great importance in the development of modern agriculture and horticulture. Herein, a novel starch carbamate (SC) modified sodium alginate (SA) hydrogel (SC/SAH) was prepared utilizing as-synthesized SC and natural SA through the cationic ions crosslinking method and ultimately the corresponding slow-release fertilizer (SC/SAH-SRF) was successfully developed by immersing the dried SC/SAH matrix into saturated urea solution. Due to the low gelation temperature and high viscosity of the synthesized SC, the formed SC/SAH exhibits significantly enhanced properties including excellent water absorbency up to 8.02 g/g with considerable repeatability, abundant pore structure and high hydrophilicity compared with the neat SAH and natural starch based hydrogel (NS/SAH). Accordingly, the SC/SAH leads to higher urea loading amount ∼ 1.28 g/g. Importantly, the resultant SC/SAH-SRF also shows superior slow-release performance, yielding a cumulative urea release of only 61.6 % within 10 h and almost completely release >16 h in water, what's more, only 58.5 % of the urea releases within 25 days and exceeding 50 days for complete release in soil column assays. The slow-release of urea from SC/SAH-SRF well complies for the first-order kinetics and accomplishes via a non-Fickian diffusion process. Moreover, the pot experiment demonstrates that the SC/SAH-SRF has higher growth promotion role for the maize seedlings than those of others. Consequently, this work provides a novel strategy for preparing environmentally friendly SRF by blending modified starch and hydrogel.

Optimizing planting density enhances the multi-scale structural characteristics and in vitro digestibility of maize starch via modulating the size distribution of granules

The modification of starch through agricultural practices is becoming increasingly significant for producing healthy foodstuffs and raw materials for industrial applications, consequently gaining momentum in academic research. This study examined how three different planting densities influenced the distribution of granule sizes, multi-scale structural characteristics, and in vitro digestibility of maize starch. The results showed that planting density significantly enhanced grain yield and relative crystallinity, and significant increases were also observed in the contents of both rapidly and slowly digestible starch. The surface- and volume-weighted mean diameter of granules significantly increased under the medium level (6.75 × 104 plants ha-1), and then decreased under high planting density level. As planting density level increased, the amylose content, peak viscosity, and hardness varied from 23.3 to 26.4 %, from 1962 to 2659 mPa·s, and from 129.3 to 307.6 g, respectively. However, no change was found in crystalline structure of maize starch. These results indicated that optimizing planting density could effectively improve grain yield and starch characteristics of maize, with the best effect under the level of 6.75 × 104 plants ha-1.

Effects of different proportions of erythritol and mannitol on the physicochemical properties of corn starch films prepared via the flow elongation method

In this study, corn films based on corn starch were fabricated through the casting method, and various plasticizers (namely, erythritol and d-mannitol) were incorporated. The study delved into the gelatinization and physicochemical characteristics of these corn starch-based films. Additionally, the impact of different ratios of plasticizers on reductive gelatinization was assessed using RVA analysis. The investigation also encompassed the effects of varying plasticizer ratios on starch granule expansion, amylose dissolution, and amylopectin melting. Interestingly, as the proportion of d-mannitol increased, there were gradual increases in film thickness, water content, and water contact angle, alongside decreases in water vapor permeability, crystallinity, and water solubility of the corn starch-based films. In essence, this research provides a fundamental basis for potential industrial applications of corn starch-based films.

The Iodine/Iodide/Starch Supramolecular Complex

The nature of the blue color in the iodine-starch reaction (or, in most cases, iodine-iodide-starch reaction, i.e., I2 as well as I- are typically present) has for decades elicited debate. The intensity of the color suggests a clear charge-transfer nature of the band at ~600 nm, and there is consensus regarding the fact that the hydrophobic interior of the amylose helix is the location where iodine binds. Three types of possible sources of charge transfer have been proposed: (1) chains of neutral I2 molecules, (2) chains of poly-iodine anions (complicated by the complex speciation of the I2-I- mixture), or (3) mixtures of I2 molecules and iodide or polyiodide anions. An extended literature review of the topic is provided here. According to the most recent data, the best candidate for the "blue complex" is an I2-I5--I2 unit, which is expected to occur in a repetitive manner inside the amylose helix.