Starch Gel Research Articles

Preliminary Study on the Influence of the Polyphenols of Different Groups on the Digestibility of Wheat Starch, Measured by the Content of Resistant Starch

The scientific goals of this research were to examine the impact of various polyphenols from different groups on resistant starch development. Wheat starch was tested, and the polyphenols were added to starch after its pasting in the amount suggested in the literature as optimal—10 mg, and at twice and half the optimal, i.e., 20 mg and 5 mg. The most frequently consumed and most frequently occurring compounds in food products were selected for the proposed research: (1) phenolic acids—p-coumaric acid, ferulic acid; (2) flavanones—hesperidin, naringenin; (3) flavanols—(+)catechin, epigallocatechin gallate; (4) flavonols—quercetin, kaempferol; (5) anthocyanins—cyanidin-3-O-glucoside, delphinidin-3-O-glucoside. As a result, either the dose or the kind of polyphenolic compound had a statistically significant influence on the wheat starch digestibility (p < 0.05). However the observed impact was dose-dependent, and interestingly, higher amounts of RS were found in the case of the lowest dose applied (5 mg—4.76% of starch gel; mean = 2.94 ± 1.23 g·100 g−1 dm) as compared to the other doses: 10 mg—9.09% of starch gel (mean = 1.58 g·100 g−1 dm) and 20 mg—16.66% of starch gel (mean = 1.51 ± 0.90 g·100 g−1 dm). Among all tested polyphenols added to wheat starch gels in an amount of 10 mg and 20 mg, epigallocatechin gallate was found to be the most effective compound (p < 0.05), while (+)catechin was most efficient in the dose of 5 mg (p < 0.05).

Highly Luminescent MOF and Its In Situ Fabricated Sustainable Corn Starch Gel Composite as a Fluoro-Switchable Reversible Sensor Triggered by Antibiotics and Oxo-Anions.

Frequent use of antibiotics and the growth of industry lead to the pollution of several natural resources which is one of the major consequences for fatality to human health. Exploration of smart sensing materials is highly anticipated for ultrasensitive detection of those hazardous organics. The robust porous hydrogen bonded network encompassing a free-NH2 moiety, Zn(II)-based metal-organic framework (MOF) (1), is used for the selective detection of antibiotics and toxic oxo-anions at the ppb level. The framework is able to detect the electronically dissimilar antibiotic sulfadiazine and nitrofurazone via fluorescence "turn-on" and "turn-off" processes, respectively. The antibiotic-triggered reversible fluoro-switching phenomena (fluorescence "on-off-on") are also observed by using the fluorimetric method. An extensive theoretical investigation was performed to establish the fluoro-switching response of 1, triggered by a class of antibiotics and also the sensing of oxo-anions. This investigation reveals that the interchange of the HOMO-LUMO energy levels of fluorophore and analytes is responsible for such a fluoro-switchable sensing activity. Sensor 1 showed the versatile detection ability which is reflected by the detection of a carcinogenic nitro-group-containing drug "roxarsone". In view of the sustainable environment along with quick-responsive merit of 1, an in situ MOF gel composite (1@CS; CS = corn starch) is prepared using 1 and CS due to its useful potential features such as biocompatibility, toxicologically innocuous, good flexibility, and low commercial price. The MOF composite exhibited visual detection of the above analytes as well as antibiotic-triggered reversible fluoro-switchable colorimetric "on-off-on" response. Therefore, 1@CS represents a promising smart sensing material for monitoring of the antibiotics and oxo-anions, particularly appropriate for the real-field analysis of carcinogenic drug molecule "roxarsone" in food specimens.

Structure, physicochemical, functional and in vitro digestibility properties of non-waxy and waxy proso millet starches

The structural, physicochemical, gel textural, rheological, and in vitro digestibility properties as well as their relationships of non-waxy proso millet starch (NPMS) and waxy proso millet starch (WPMS) were evaluated by taking normal corn starch (CS) and potato starch (PS) as controls. Proso millet starch was mostly polygonal or spherical, with an A-type crystalline structure. Proso millet starch contained more short-branched chains (DP 6–24) compared with CS and PS. WPMS possessed higher crystallinity and more short-range ordered structures than NPMS. NPMS displayed higher pasting temperature, retrogradation rate and shear thinning degree, and lower gelatinization temperature and enthalpy than WPMS. The hardness and chewiness of starch gel formed by NPMS were higher than those of WPMS. All starch samples exhibited shear thinning behavior in the steady-flow test and typical elastic solid behavior in the dynamic rheological test. Moreover, NPMS was considered a potential formula for functional foods, with its lower rapidly digestible starch (RDS) and higher resistant starch (RS) contents than WPMS, CS, and PS. This paper revealed the influence of amylose content and structure on the physicochemical properties of different proso millet starch.

Low-Field NMR Analyses of Gels and Starch-Stabilized Emulsions with Modified Potato Starches

Many different biopolymers are used to stabilize emulsions, of which starch is of particular concern. To improve the characteristics and technical utility of native starch, various types of changes can be made. This article is a report describing the molecular dynamics of water by the low-field nuclear magnetic resonance (LF NMR) of chemically (E 1412 and E 1420) and physically modified starch (LU 1432) gels and the effect of their use on the stability of oil/water emulsions obtained using bovine and porcine fats. The analysis of changes in spin–spin and spin–lattice relaxation times over time showed that the presence of the type of starch modification significantly affects the values of T1 and T2 relaxation times, as well as the correlation times. Research on time-related changes in water binding in oil-in-water emulsions showed that potato starch modified by chemical methods can be used as an emulsifier. Compared to physically modified starch, chemically modified starches have a much better water-binding capacity.

Impact of Low‐Pressure Argon Plasma on Structural, Thermal, and Rheological Properties of Corypha umbraculifera L. Starch: A Non‐Conventional Source of Stem Pith Starch

AbstractThe impact of low‐pressure argon plasma on structural, pasting, rheological, and thermal characteristics of starch from talipot palm (Corypha umbraculifera L.) is analyzed. Talipot palm is a non‐conventional source of starch. The starch is subjected to a different plasma power with different time duration. Exposure of talipot starch to plasma with different power (7.5 and 15 W) and time (30 min and 1 h) significantly affects the physicochemical and functional properties. SEM micrographs show that the plasma treatment causes severe damage to the granule surface. The pasting profile of talipot starch is considerably decreased by plasma treatment. The relative crystallinity and thermal properties are also decreased by plasma treatment. Plasma‐treated talipot starches exhibit a decreased storage and loss modulus indicating weak gel formation. However, the treatment considerably increases the paste clarity of the starch gel.

Enzymatic potato starch modification and structure-function analysis of six diverse GH77 4-alpha-glucanotransferases

4-α-glucanotransferase (EC 2.4.1.25) mediated glucan transfer in starch provides opportunities for production of clean label starch ingredients with unique gelling properties. 4-α-glucanotransferases can be found in glycoside hydrolase (GH) family GH13, GH57, and in the monospecific glycoside hydrolase family 77 (GH77). Here, pH-temperature optima, steady-state kinetics, potato starch modifying properties and structural folds are reported for six phylogenetically distinct GH77 members, representing four different domain architectures including a novel multi-domain 4-α-glucanotransferase from Lactococcus lactis. Four of the enzymes exhibited starch modifying activity leading to a gradual decrease of the amylose content, elongation of amylopectin chains, and enabled formation of firm starch gels. Unexpectedly, these diverse enzymes catalyzed similar changes in chain length distributions. However, the amylose depletion and amylopectin elongation rates spanned more than two orders of magnitude between the enzyme showing very different specific activities. Tt4αGT from Thermus thermophilus had highest temperature optimum (73 °C) and superior potato starch modifying efficacy compared to the other five enzymes.

Physicochemical properties of a new starch from turion of Spirodela polyrhiza

Starch from the turion of Spirodela polyrhiza ZH0196 is a new resource with great development values. The solubility, swelling power, thermogravimetric analysis (TGA), enzyme susceptibility, and in vitro digestibility of Spirodela starch, paste clarity, settling volume, and the rheology property of Spirodela starch paste, strength, elasticity, and freeze-thaw stability of Spirodela starch gel were studied. The properties of Spirodela starch were compared with those of normal corn starch and rice starch. The possible relationship between properties and structure of three kinds of starch was analyzed by principal component analysis (PCA). The results showed that the rapidly digested starch, slowly digested starch and resistant starch were 86.63 %, 4.43 %, and 8.94 % respectively. Spirodela starch has higher strength (17.77 g), elasticity (4.98 g/s) of starch paste, and freeze-thaw stability of starch gel than those of normal corn starch and rice starch. The rheological results showed that the stickiness maintainability of starch paste was normal corn >Spirodela > rice and Spirodela starch paste had compact paste structures with the tan δ between 0.33 and 0.38. This study has significant value in the application of Spirodela starch.

Effects of egg white on physicochemical and functional characteristics of steamed cold noodles (a wheat starch gel food)

Steamed cold noodles (SCN) is a popular wheat starch-based (gluten-free) gel food in China. However, some textural and nutritional problems are existed because of the single component (mainly starch and water), such as easy breakage, lack of toughness and high glycemic index. In this paper, egg white was introduced into SCN, and the impacts on texture, rheological properties, gel properties and functional properties of SCN were studied. The introduction of egg whites increased the hardness, chewiness, resilience, shear resistance of gel, and increased the water holding capacity of the gel from 87% to approximately 94%. At the same time, a significantly different in digestibility was seen between SCN with and without egg white. Egg whites made the whole polysaccharide gel system more compact. These results suggested that egg whites can improve the gel characteristics and functional properties of starch gel, contributing to the development of new gluten-free foods.

The Synthesis of Cu–Mn–Al Mixed-Oxide Combustion Catalysts by Co-Precipitation in the Presence of Starch: A Comparison of NaOH with Organic Precipitants

Cu–Mn mixed oxides are well known as active combustion catalysts. The common method for their synthesis is based on co-precipitation, with NaOH as a precipitant, and is burdened with the possibility of introducing undesired Na contamination. This work describes the use of two organic bases, tetrabutylammonium hydroxide and choline hydroxide, as precipitating agents in a novel alkali-free route for Cu–Mn–Al catalyst synthesis. To obtain fine crystalline precursors, which are considered advantageous for the preparation of active catalysts, co-precipitation was carried out in the presence of starch gel. Reference materials prepared with NaOH in the absence of starch were also obtained. Mixed oxides were produced by calcination at 450 °C. The precursors contained MnCO3 doped with Cu and Al, and an admixture of amorphous phases. Those prepared in the presence of starch were less crystalline and retained biopolymer residues. The combustion of these residues during calcination enhanced the formation of larger amounts of the Cu1.5Mn1.5O4 spinel phase, with better crystallinity in comparison to catalysts prepared from conventionally synthesized precursors. Tests of toluene combustion demonstrated that the catalysts prepared with starch performed better than those obtained in starch-free syntheses, and that the mixed oxides obtained by the alkali-free route were more active than catalysts prepared with NaOH. Catalytic data are discussed in terms of property–performance relationships.

The role of starch granule-associated proteins in enhancing the strength of indica rice starch gels

The gel properties of indica rice starch strongly influence the quality of foods in which it is used. This study investigated the effects of chymotrypsin treatment on the rheological and pasting properties of starch prepared by different treatment methods. The results demonstrated that all the starches contained starch granule-associated proteins (SGAPs). Specifically, chymotrypsin-treated fermented extracted starch (E-FS) and chymotrypsin-treated alkali extracted starch (E-AS) exhibited a storage modulus (Gʹ) about 4 times higher than that of fermented extracted starch (FS) and alkali-extracted starch (AS). The flow consistency coefficients (K), loss moduli (Gʺ) and setback values tended to increase, while the characteristic rheological indices (n) and loss tangent (tan δ) tended to decrease after chymotrypsin treatment. This suggested that the starch gel was significantly enhanced by the proteinase modification. The protein composition of AS and E-AS only contained the 66 kDa of granule-bound starch synthase I (GBSS I) subunit. Therefore, the significant increase in gel strength was attributed to the exclusive modification effects of GBSS I. Microstructural analysis also confirmed that the three-dimensional gel network of indica rice starch was formed by a backbone of SGAP polymers filled with starch granules. The mechanism underlying GBSS I-enhanced gel was also elucidated based on the sequence and structure of GBSS I. The gel network formed by SGAP polymers of FS and AS was mainly caused by disulfide bonds between GBSS Is, while that of E-FS and E-AS was mainly caused by hydrophobic interactions. • The gel properties of indica starch treated by different methods were studied. • Enzymatic modification of starch granule-associated proteins (SGAPs) increased the starch gel strength significantly. • The SGAPs were mainly composed of granule-bound starch synthase I (GBSS I). • Gel formation driving force changed from disulfide bonds to hydrophobic interactions. • The gel structure comprised a polymerized SGAP network filled with starch granules.

Starch controls brittleness in emulsion-gels stabilized by pea flour

Pea proteins are widely studied as emulsifying and gelling agents in soft food materials. However, their extraction process consumes energy and often focuses only on protein purity. To reduce extraction-related energy consumption, unpurified pea protein-starch mixtures could be used directly as functional ingredients. Such mixtures provide additional advantages due to their binary role, such as using proteins as emulsifiers and starch as a gelling agent. Therefore, we investigated the heat-induced gelation of emulsions (30 or 50% oil), stabilized by pea flour (PF) containing 20 wt% protein and 50 wt% starch. To understand the effect of starch on gelation, starch was removed from pea flour by filtration. Heat-induced gelation behavior of the pea protein mixture (PPM) stabilized emulsions was investigated and compared with PF emulsions. Both the PF and PPM stabilized emulsions gelled upon temperature treatment, monitored by oscillatory shear rheology. At pH 7, starch (in PF) contributed to a higher G' (2000Pa) compared with the emulsions without starch (PPM:∼1000 Pa). Whereas, at pH 3, the presence of starch did not contribute to a higher G′ in the emulsions. The presence of starch at both pH values affected the microstructure of the emulsion gels. The PF emulsions after heating were more brittle upon applying strain compared to the PPM emulsions. The brittle nature of the emulsions containing starch was most likely due to the starch gel's disruption of the oil droplet network. Our results provide insight into emulsion gelation when using a native pea protein-starch mixture. Our study demonstrates that depending on the pH conditions, native protein blends could have better gelling functionality.

Variable Effects of Twenty Sugars and Sugar Alcohols on the Retrogradation of Wheat Starch Gels.

Starch retrogradation is desirable for some food textures and nutritional traits but detrimental to sensory and storage qualities of other foods. The objective of this study was to determine the impact of sweetener structure and concentration on the retrogradation of wheat starch gels. The effects of 20 sweeteners selected based on common food usage and stereochemical structures of interest, and ranging in concentration from 10 to 50%w/w, on the retrogradation of wheat starch gels were monitored spectrophotometrically over time. The sweeteners were sucrose, xylose, ribose, glucose, galactose, fructose, mannose, mannitol, L-sorbose, xylitol, tagatose, allulose, maltose, lactose, isomaltulose, isomalt, sorbitol, maltitol, and raffinose. Retrogradation rates and amounts were compared by Avrami equation rate constants (k = 0.1–0.7) and absorbance values measured on day 28 (Abs = 0.1–1.0), respectively. Both sweetener concentration and type significantly affected retrogradation. Gels made with sugar alcohols and high sweetener concentrations (≈≥40%) tended to retrograde more and faster, whereas gels made with sugars and low sweetener concentrations tended to have lower retrogradation rates and amounts. Sweeteners with more equatorial and exocyclic hydroxyl groups (e.g., glucose and maltitol) and those with larger molar volumes (e.g., isomaltulose and raffinose) tended to increase the rate and amount of retrogradation, particularly at higher concentrations. The impact of sweeteners on retrogradation was a balance of factors that promoted retrogradation (intermolecular interactions and residual short-range molecular order) and inhibiting behaviors (interference at crystallization sites), which are influenced by sweetener concentration and structure. Understanding which sweeteners at which concentrations can be used to promote or inhibit retrogradation is useful for product formulation strategies.

The physicochemical properties of starches isolated from defatted tigernut meals: Effect of extrusion pretreatment

If the tigernut meal left after oil extraction is used as a material for starch resources instead of being wasted, the industrial value of tigernut would be improved. Thus, we investigated the effect of extrusion before oil extraction on the yield, structure and function of starches within tigernut meals (TMS). Compared with the yield of native starch, the yield of TMS-130-11 (barrel temperature: 130 °C; feed moisture: 11 %) was increased by 1.97 %, and that of TMS-140-11 (barrel temperature: 140 °C; feed moisture: 11 %) was decreased by 7.82 %. The starches cannot be obtained when the barrel temperature is above 140 °C with 11 % feed moisture. Extrusion slightly decreased the relative crystallinity and increased the ratio of B2-chains in amylopectin. These changes resulted in reductions in peak viscosity while improving the elastic properties of the starch gel. These results will provide useful information regarding the use of starch isolated from tigernut meal.

An Insight into Pasting and Rheological Behavior of Potato Starch Pastes and Gels with Whole and Ground Chia Seeds.

With regard to technological innovations, we applied chia (oilseeds) as a stabilizer additive in a normal and waxy potato starch sample to obtain stable starch-based gels during 20 days of storage. The aim of this study was to investigate the 5% w/w normal and waxy potato starch pastes (hot samples) and gels (cold samples) with the addition of 1% w/w whole and ground chia seeds properties as pasting and flow properties of pastes and textural properties of gels. The pasting process using a viscograph showed that normal and waxy potato starch with the addition of chia had a different pasting characteristic. The addition of chia seeds had a greater effect on the properties of normal potato starch than waxy potato starch. From a rheological point of view, starch pastes without chia were less theologically stable as they showed bigger areas of hysteresis loops. Minor changes in the hardness of gels were obtained in normal starch gels with chia seeds during 20 days of storing compared to the samples without chia seeds, whereas in the waxy starch gels, the effect was the opposite.

Physicochemical, Morphological, Thermal, and Rheological Properties of Native Starches Isolated from Four Cultivars of Anchote (Coccinia abyssinica (Lam.) Cogn.) Tuber.

Anchote (Coccinia abyssinica (Lam.) Cogn) is a potentially important source of starch and an underutilized root and tuber crop indigenous to Ethiopia. In this study, the physicochemical, morphological, thermal, and rheological properties of native starches isolated from four cultivars of anchote tubers were studied and compared to potato and cassava starches, which were considered as references. The amylose content of anchote starches varied from 15.8–22.3%. The anchote cultivars showed different granule sizes, but all revealed a B-type crystalline structure, identical to potato starch. The phosphorus content of anchote starches ranged from 82–93 mg/100 g and was much higher than that of potato and cassava (60.3 and 5.8 mg/100 g, respectively). This characteristic could govern several functional properties of anchote starches, making them suitable for applications in different types of noodles, glucose syrups, and viscous products. The gelatinization temperature and enthalpy of anchote starches, which ranged from 60.97 °C to 69.33 °C and 16.87 to 18.38 J/g, respectively, were considerably different compared to potato and cassava starches. Significant variations were also observed among the pasting properties of starches from anchote cultivars. They showed a higher stability to heating and shearing, having higher TV (2046 to 2280 mPa·s) and lower BV (248 to 487 mPa·s) values, and a higher final viscosity (3409 to 3686 mPa·s) than potato and cassava, which are important characteristics in food processing and when high gel viscosity is required after cooling. Anchote starch gels exhibited rheological characteristics of true gels, showing much lower (tan δ)1 values and significantly higher viscoelastic moduli than those found in cassava and potato gels. The present study revealed significant differences among the physicochemical properties of anchote starches, depending on the cultivar, and demonstrated their promising potential in food product development and other industrial applications.

Evaluation of Cassava (Manihot esculenta) and Sweet Potato (Ipomea batatas) Starch from South East Nigeria in the Separation of Deoxyribonucleic Acids as Alternative to Agarose Gel

Gel electrophoresis technique is an indispensable tool in biotechnology and among other related fields for separation of nucleic acids and proteins. This study determined the potential of selected cassava and sweet potato starch in the separation of DNA as alternative to agarose gel. The sample pH, gelling temperature and time were determined by Light transmittance method proposed by Craig et al. [1] Standard electrophoresis procedure was used for the starch gel electrophoresis. The result showed that composite starch gelled within 18-21 minutes while agarose and agar-agar gelled after 12 minutes. Cassava starch blended with agar-agar gelled at a temperature of 58oC while sweet potato starch blended with agar-agar gelled between 35oC - 47oC. Agarose and agar-agar maintained 54oC and 53oC respectively. There was no significant difference (P > 0.05) in pH value of the composite starch when compared to 1% agarose gel. Unblended starch samples did not form solid gel except when blended with some amount of agar-agar or agarose powder. Cassava and sweet potato composite starch formed good gel strength at 3% (2.2 g of starch and 0.8 g of agar-agar) but solid gel at 4% (3.6 g of starch and 0.8 g of agar-agar). This study demonstrated the possibilities for agarose cost reduction by 60% when cassava starch (3.6 g) was blended with 0.4 g of agarose. The cassava composite starch (4%) separated DNA molecules comparably to that of 1% agarose. Therefore, the use of these cheaper, accessible and readily available blended starch sources is highly recommended for separation of biomolecules such as DNA.

Eco-friendly additive construction: Analysis of the printability of earthen-based matrices stabilized with potato starch gel and sisal fibers

• A prototype 3D printing system for construction ecofriendly composites was developed. • A printable composite made with soil, starch gel, and fibers was designed. • The inclusion of starch gel positively affects properties in fresh and hardened state. • The incorporation of sisal fibers allow controlling shrinkage cracking in printed filaments. 3D printing for construction purposes is a disruptive technology with the potential for rapid and massive applications making it a feasible alternative for social housing, temporary shelters after disasters, and, recently, for extraterrestrial habitats. However, most of the matrices used for construction by 3D printing are based on hydraulic cement as the main constituent, which is not easily available in remote locations and is an important greenhouse gases generator. Therefore, a good understanding to formulate and evaluate alternative matrices using soil and organic materials with the required fresh and hardened-state properties compatible with this emerging technology is needed. This article studies the printable capabilities of eco-friendly earthen-based matrices which uses potato starch as a natural stabilizer for raw soil mortars aiming to obtain 3D printed filaments with adequate fresh and hardened-states properties. The aqueous starch gel was combined with sisal fibers in the printing mixture to control shrinkage cracking problems during hardening. The optimization of the dosage of the stabilizer was carried out considering different tests in fresh and hardened printed filaments namely, pumpability and extrudability, stacking, shear vane, shrinkage cracking, Vicat needle, compression strength, and capillarity absorption tests. The results indicate that printable earthen-based matrices reinforced with 1 % of sisal fibers by weight of soil and stabilized with aqueous starch gels with concentrations up to 5 % (w/w) showed improved workability and minor cracking and can be used for 3D printing. These promising results in the field of material science combined with novel 3D printing technology that is also presented in the article open new lines of research for eco-friendly alternatives for the construction industry.

Influence of plasma-activated water on the morphological, functional, and digestibility characteristics of hydrothermally modified non-conventional talipot starch

The starch isolated by the alkali method from talipot palm ( Corypha umbraculifera L . ) stem pith is a non-conventional starch with a high yield (76%). Talipot starch was subjected to hydrothermal treatments, heat-moisture treatment (HMT) and annealing (ANN) with plasma-activated water (PAW). HMT and ANN with PAW created fissures and surface degradation and significantly increased (p ≤ 0.05) the relative crystallinity of talipot starch from 16.91% to 26.96%. The increased crystalline perfection of modified starch significantly decreased (p ≤ 0.05) the swelling power and increased the pasting temperature, gelatinization temperature, and gelatinization enthalpy. The significant decrease (p ≤ 0.05) in peak and breakdown viscosities and enhancement in storage and loss moduli indicates improved shear and thermal stability of modified starch gels. PAW with acidic nature decreased the starch digestibility and increased the resistant starch content to 51.03% and 52.11% after HMT and ANN treatments, respectively. The reactive species present in the PAW reduced the retrogradation tendency by reducing the setback and final viscosities and improving the paste clarity of modified starches. PAW modified starch gel possessing enhanced paste clarity is suitable for the preparation of pie fillings, soups and sauces. Hydrothermal treatments with PAW can be regarded as a novel technique to modify starch without enzymes, acids, or cross-linking agents to improve the functionality, reduce retrogradation tendency and increase resistant starch content. • Heat-moisture treatment (HMT) and annealing (ANN) were done on talipot starch. • HMT and ANN with plasma-activated water (PAW) increased starch crystallinity. • Hydrothermal treatment with PAW enhanced the thermal stability of talipot starch. • HMT and ANN with PAW showed reduced retrogradation tendency in talipot starch. • Hydrothermal treatment with PAW increased the resistant starch content.

A Decreased Nitrogen Rate with Increased Planting Density Facilitated Better Palatability of Conventional japonica Rice at High Yield Levels

A decreased nitrogen (N) rate with increased planting density (DNID) is recommended as a feasible method to maintain rice grain yield and N-utilization efficiency. However, it is still unclear whether DNID could improve grain quality, particularly the edible quality of rice. Three high-yield rice with superior palatability (HYSP) and three high-yield rice with inferior palatability (HYIP) were grown under DNID and local cultivation practices (LCP) in the same paddy fields during the 2018 and 2019 rice planting seasons. HYSP exhibited similar grain yields to HYIP under both cultivation treatments. HYSP had more spikelets per m2 through panicles per m2, while having lower spikelets per panicle and 1000-kernel weight than HYIP. DNID increased panicles per m2 and 1000-kernel weight and decreased spikelets per panicle of HYSP and HYIP compared with LCP. HYSP exhibited more biomass accumulation during heading to maturity under NDID and LCP (p < 0.05), which is supported by a higher leaf area index (LAI) and SPAD values after heading. DNID reduced shoot biomass weight and non-structural carbohydrate, while increasing harvest index and NSC remobilization reserve, especially for HYSP (p < 0.05). HYSP had a higher amylopectin content, total starch content, gel consistency, stickiness, and overall palatability (p < 0.05), while it had a lower hardness (p < 0.05) than HYIP. Compared with LCP, DNID increased the amylose content, amylopectin content, total starch content, gel consistency, stickiness, and overall palatability, while it decreased grain protein content and hardness of HYSP and HYIP. HYSP showed consistently higher peak viscosity, breakdown, and gelatinization temperatures (p < 0.05), while it showed lower setback (p < 0.05) than HYIP. For HYSP and HYIP, DNID increased the peak viscosity, breakdown, and gelatinization temperatures (p < 0.05), while it decreased the setback compared with LCP. Generally, the results indicated that coordinated yield components, more post-heading biomass accumulation, lower amylose content, higher peak viscosity and breakdown with lower setback, and higher gelatinization temperatures facilitated high-level grain yield and excellent cooked rice palatability of HYSP. DNID is a feasible method to maintain rice grain yield and enhance the quality of cooked rice for edible properties.

Physicochemical properties and correlation analysis of retrograded starch from different varieties of sorghum

SummarySorghum germplasm resources were abundant, and their comprehensive utilisation was also more in‐depth. Starch had attracted much attention as the main component in grain, but starch retrogradation limited its better development and utilisation. Therefore, the property changes of sorghum starch retrogradation were studied. The differences in the properties of the four kinds of sorghum starches during retrogradation were mainly due to composition and structure among the varieties. With the increase in retrogradation days, the order of L1 starch was better at 0.994, the retrogradation rate of L13 starch increased by 36.23%, and the recrystallisation degree of H5 starch was 0.064 worse than that of native starch. However, the physicochemical properties of H1 retrograded starch were different from those of the other three. It was shown that the solubility increased to 47.67%, the transparency was 43.36%, and the water‐holding capacity was 91.35%. Retrogradation made that the surface of sorghum starch gel fragments had an orderly scale‐like structure, which did not cause the generation of new groups, reduced the crystalline strength and the energy required for gelatinisation. The crystallisation rate was positively correlated with syneresis, swelling and orderliness, as well as T0, Tp, Tc and ΔH, and negatively correlated with water‐holding capacity.