An insight into the multi-scale structures and pasting behaviors of starch following citric acid treatment

Superheated steam processing as a novel strategy for rapid synthesis of millet-starch citrates: Preparation, characterization, and in vitro starch digestibility

This study investigates the potential of superheated steam (SS) as a rapid and sustainable method for synthesising millet starch citrates with improved physicochemical and functional properties. Millet starch was esterified with citric acid (CA) under varying SS conditions (160-180 °C, 15-45 min) to optimise the degree of substitution (DS) and evaluate its influence on starch functionality. A range of DS values (0.023 to 0.121) were achieved, with the highest DS observed at 170 °C for 45 min. Structural analysis using Fourier-transform infrared spectroscopy confirmed successful esterification, with the appearance of a new peak at 1735 cm-1 indicating ester bond formation. X-ray diffraction showed a reduction in crystallinity with increasing DS, while polarised light microscopy and confocal scanning laser microscopy revealed alterations in molecular organisation. Scanning electron microscopy demonstrated minimal disruption to granule morphology. Contact angle measurements indicated increased hydrophobicity, with water contact angles rising from 29.63° in native starch to 71.63° in high DS samples. Additionally, a significant (p < 0.05) reduction in amylose content and paste viscosities was observed, correlating with improved resistance to gelatinisation and retrogradation. In vitro digestibility analysis showed a substantial increase in resistant starch content, from 18.69 % in native starch to 40.11 % in high DS samples. These findings highlight SS as an efficient and eco-friendly technology for producing starch citrates with tailored functionalities, particularly suited for low-glycaemic response and health-promoting food applications.

Micro N2-bubble-assisted esterification or crosslinking of corn starch by citric, lactic and malic acid: Facilitating the reaction medium under hydrodynamic cavitation

This comparative study explores an innovative approach to enhance corn starch's resistant fraction through microbubble-assisted esterification. The modified starches showed reduced crystallinity and a higher degree of substitution (0.32 % to 0.49 %) in MAE compared to native esterified starches (0.24-0.37 %). FT-IR analysis identified a new absorption band at 1762 cm-1, signaling the CO stretching vibration associated with ester bonds formed between starch and L-malic, L-lactic, and L-citric acids. The resistant starch pattern produced by lactic acid significantly differed from citric and malic acid; RS fragments exhibited smooth surfaces and a compact, fused structure, particularly notable in LNC and LMC samples. Lactic acid, through esterification, reacted with starch hydroxyl groups, boosting RS levels and lowering rapidly digestible starch compared to citric and malic acids, acting as crosslinkers. The lack of peaks in the RVA pasting profiles confirmed successful crosslinking or esterification, significantly altering the starch's pasting characteristics. Hydrodynamic cavitation provides multiple benefits for physically modifying starch and providing a reaction medium for esterification or cross-linking. These include minimizing chemical input, reducing processing duration, and offering high selectivity and product quality, further enhancing its environmental sustainability.

A comprehensive review on methods, mechanisms, properties, and emerging applications of crosslinked starches

Native starches exhibit limitations in terms of low thermal stability, poor paste clarity, and high retrogradation. Crosslinking is a modification method that has been employed to address these shortcomings by introducing intra- and inter-molecular bonds to enhance the properties of starch. Sodium trimetaphosphate (STMP), citric acid (CA), and epichlorohydrin (ECH) are widely used crosslinking agents that enhance the thermal stability, mechanical properties, and resistance to enzymatic degradation of starches. However, the changes in starch properties are highly dependent on the type and concentration of crosslinkers and source of starch. Therefore, the present review comprehensively explores the methods, mechanisms, and parameters affecting the crosslinking process of starches. Additionally, it highlights the potential of crosslinked starches in emerging fields like hydrogels, aerogels, biodegradable films, and adsorbents.

Increasing degree of substitution inhibits acetate while promotes butyrate production during in vitro fermentation of citric acid-modified rice starch

Citric acid-modified starch functions as a resistant starch, while the combined effects of its fine molecular structure and degree of substitution on gut microbiota are not well understood. To this end, citric acid-modified starches with varying degrees of substitution were synthesized from rice starches with distinct molecular structures and their impact on gut microbiota composition and short-chain fatty acid (SCFA) production was analyzed. Notably, rice starch with a higher degree of substitution significantly reduced acetate production, while promoted butyrate production. Correlation analysis further suggested that amylopectin chains with 12 < DP ≤ 36 and amylose chains with 100 < DP ≤ 500 alter the growth of Faecalibacterium_prausnitzii and Bacteroides_vulgatus, consequentially determining the production of SCFAs. Collectively, these findings indicate that citric acid-modified rice starch with different degrees of substitution can target specific gut bacteria and SCFA production, thus conferring beneficial impact on human health.

Effect of cation valence on the retrogradation, gelatinization and gel characteristics of maize starch

This study aimed to examine the impact of trivalent, divalent, or monovalent cations dissolving into water and being mixed with maize starch to influence its retrogradation, gelatinization, and gel characteristics. The result of the analysis using a differential scanning calorimeter showed that all cations raised the peak of gelatinization temperature of maize starch, especially Al3+ or Fe3+, while trivalent cations reduced the enthalpy. The result of the analysis using a rapid viscosity analyzer showed that trivalent cation caused lower trough viscosity, final viscosity, and pasting temperature but higher breakdown viscosity of maize starch than monovalent or divalent cations. Confocal laser scanning microscopy showed that the cation promoted the destruction of gelatinized maize starch granules, especially Zn2+, Fe3+, or Al3+. Additionally, trivalent Fe3+ or Al3+ caused higher gel strength of maize starch. Generally, the cation with higher valence changed more retrogradation, gelatinization, and gel characteristics of maize starch.

Insights into the effect mechanism of acidic pH condition on the in vitro starch digestion of black highland barley semi-dried noodles

In this study, black highland barley semi-dried noodles (BHBSNs) were adjusted to acidic pH (5.0, 4.5, 4.0) with an acidity regulator (monosodium fumarate) for obtaining low glycemic index (GI) BHBSNs, and the changes in the in vitro starch digestion, free phenolic content, and α-amylase activity in BHBSNs were investigated. The estimated glycemic index (eGI) of BHBSNs decreased from 59.23 to 52.59, 53.89 and 53.61, respectively, as the pH was adjusted from 6.0 to 5.0, 4.5, 4.0. As the pH of BHBSNs decreased, the equilibrium hydrolysis (C∞) decreased, and kinetic coefficient (k) decreased and then increased. Compared to the control, the pH of the digestive fluid decreased during digestion with decreasing pH, and the α-amylase inhibition of BHBSNs with pH 5.0, 4.5, and 4.0 increased by 56.54 %, 75.18 %, and 107.98 %, respectively. In addition, as the pH of BHBSNs decreased, the free phenolic content and the content of released phenolics during digestion increased. Pearson correlations analysis showed that the increase in α-amylase inhibition and phenolic release during digestion induced by acidic pH was negatively correlated with the eGI and C∞ of BHBSNs. This study indicated that acidic pH condition could modulate starch digestion for preparing low GI BHBSNs.

Effects of cation valence on swelling power, solubility, pasting, gel strength characteristics of potato starch

The objective of this study was to investigate the effects of monovalent, divalent and trivalent cations on the physicochemical properties of potato starch. Cations decreased the water absorption in potato starch granules to cause lower swelling power, especially 0.02-0.04 mmol/g Fe3+ or 0.01-0.04 mmol/g Al3+, but 0.01 mmol/g trivalent cation led more amylose dissolving into the water to cause higher solubility. High concentration of divalent or trivalent cations markedly decreased the viscosity in potato starch paste during further heating and cooling, resulting in the decreases of the trough and finial viscosity, especially 0.04 mmol/g Fe3+. Higher valence of cations decreased the gel strength in potato starch, especially 0.02-0.04 mmol/g Fe3+ or Al3+. Higher valence of cations decreased the starch gel binding with the water and caused lower water holding capacity. In general, a higher valence of cations caused more changes in the physicochemical characteristics of potato starch.

Long-term straw return improves cooked indica rice texture by altering starch structural, physicochemical properties in South China

Straw return can improve rice eating quality by modifying starch formation from long-term field trials, whereas the relevant mechanisms are still unknown. A long-term field experiment, including straw removal (CK), straw burning return (SBR), and straw return (SR) was conducted to investigate the starch structure, physicochemical properties, and cooked rice textures of indica early- and late-rice. Compared with CK, SBR and SR enhanced relative crystallinity, amylopectin long chains in both rice seasons, and gelatinization temperatures in late rice. Compared to SBR, SR decreased protein content and amylopectin short chains but increased starch branching degree, breakdown, and stickiness, ultimately contributing to improved starch thermal and pasting properties. Meanwhile, SR decreased hardness, cohesiveness, and chewiness, resulting in cooked texture meliorated, which was mainly attributed to amylopectin chain length and starch granule size. The results suggest that SR increased cooked texture of indica rice by altering starch structural and physicochemical properties.

Structural, rheological, and gelling characteristics of starch-based materials in context to 3D food printing applications in precision nutrition

Starch-based materials have viscoelasticity, viscous film-forming, dough pseudoplasticity, and rheological properties, which possess the structural characteristics (crystal structure, double helix structure, and layered structure) suitable for three-dimensional (3D) food printing inks. 3D food printing technology has significant advantages in customizing personalized and precise nutrition, expanding the range of ingredients, designing unique food appearances, and simplifying the food supply chain. Precision nutrition aims to consider individual nutritional needs and individual differences, which include special food product design and personalized precise nutrition, thus expanding future food resources, then simplifying the food supply chain, and attracting extensive attention in food industry. Different types of starch-based materials with different structures and rheological properties meet different 3D food printing technology requirements. Starch-based materials suitable for 3D food printing technology can accurately deliver and release active substances or drugs. These active substances or drugs have certain regulatory effects on the gut microbiome and diabetes, so as to maintain personalized and accurate nutrition.

Insight into the spatial distribution and interaction model of heat-induced micro- and nano-starch/myofibrillar protein blends

This work investigated the gelatinizing and hydration properties of raw and milled tapioca starches at micron and nano scale as well as their effects on gelation of myofibrillar proteins (MP) from Ctenopharyngodon idellus by analyzing rheology, texture and microstructure of heat-induced MP/starch blends. Milling induced starch granules damage to micron and nano scale, causing a fall in starch swelling power and a jump in water solubility. Among raw and milled starches, nano-starch had the best reinforcement effect on MP gel, i.e., MP/nano-starch showed the lowest critical gel concentration, highest G', strongest resistance to deformation and highest texture performance. Correlation analysis revealed that starch water solubility was responsible for the reinforced MP gel rather than starch swelling power. A schematic model was proposed for illustrating the interaction of starches and MP. All the blends had the ordered filamentous network as the basic skeleton, with some starches (granules and their fragments) in the voids or on the edge or surface of MP filaments as inert fillers, and some (chain segments) embedded in the filaments as active fillers. Almost all nano-starch were actively filled into the MP filaments to enhance the strength of filaments, thus achieving the best reinforcement effect on MP gel.

A Prospective Review on the Research Progress of Citric Acid Modified Starch

Citric acid (CA) treatment is a convenient, mild and environmentally friendly strategy to modify the composition, structure and function of starch through hydrolysis and esterification, which expands the application of starch in industry. In this paper, the effects of CA modification on amylose content, amylopectin chain length distribution, microscopic morphology, solubility and swelling ability, thermodynamic properties, gelatinization properties, digestibility properties, texture properties and the film-forming properties of starch were summarized. The application status and development trend of CA modified starch were reviewed, which has important implications for the targeted utilization of CA modified starch in the future.

Improving Properties of Starch-Based Adhesives with Carboxylic Acids and Enzymatically Polymerized Lignosulfonates

A novel strategy for improving wet resistance and bonding properties of starch-based adhesives using enzymatically polymerized lignosulfonates and carboxylic acids as additives was developed. Therefore, lignosulfonates were polymerized by laccase to a molecular weight of 750 kDa. Incorporation of low concentrations (up to 1% of the starch weight) of 1,2,3,4-butanetetracarboxylic acid (BTCA) led to further improvement on the properties of the adhesives, while addition of greater amounts of BTCA led to a decrease in the properties measured due to large viscosity increases. Great improvements in wet-resistance from 22 to 60 min and bonding times (from 30 to 20 s) were observed for an adhesive containing 8% enzymatically polymerized lignin and 1% BTCA. On the other hand, the addition of citric acid (CA) deteriorated the properties of the adhesives, especially when lignosulfonate was present. In conclusion, this study shows that the addition of the appropriate amount of enzymatically polymerized lignosulfonates together with carboxylic acids (namely BTCA) to starch-based adhesives is a robust strategy for improving their wet resistance and bonding times.

Physical modification of maize starch by gelatinizations and cold storage

The effects of gelatinization at three selected temperatures (DSC characteristic peaks temperature: TO, TP, and TC) and subsequent cold storage (CS) treatment on structural characteristics, pasting, and rheological properties of maize starch (MS) were investigated. The pasting, rheological properties of MS was changed with the increase of gelatinization temperature from TO to TC, but were not further significantly changed if the gelatinization temperature was higher than TC. Pasting and thermal properties analysis suggested that gelatinization at TC (TC treatment) significantly increased the gelatinization and pasting temperature of MS. Moreover, TC treatment decreased breakdown viscosity by 8.49 times and setback viscosity by 2.53 times. Dynamic rheological measurements revealed that the TC treatment caused the lower G' and G" of MS, and decreased the thickening coefficient by 55.17 %. These results indicated that TC treatment could enhance the thermal stability properties of MS, inhibiting the shear and short-term retrogradation, the shear-thinning behavior of MS. Interestingly, the CS treatment further inhibited the shear and short-term retrogradation and the shear-thinning behavior of MS. The leaked starch molecules aggregate to form a harder structure after gelatinization and starch molecules were further aggregated after CS treatment, these all were hypothesized to be responsible for these results.

Formation and structural evolution of starch nanocrystals from waxy maize starch and waxy potato starch

The formation and structural evolution of starch nanocrystals from waxy maize starch (WMS) and waxy potato starch (WPS) by acid hydrolysis were studied. The relative crystallinity, the short-range molecular order, and the double-helix content of WMS and WPS increased significantly during the initial stage of acid hydrolysis, indicating that acid preferentially eroded the amorphous regions of starch granules. With time, there was increased destruction of lamellar structures, causing the granules to completely disintegrate to form nanocrystals. WMS and WPS displayed different hydrolysis mechanisms. WPS was more susceptible to acid hydrolysis than WMS, and WMS exhibited an endo-corrosion pattern and WPS showed an exo-corrosion pattern. WMS nanocrystals had a parallelepiped shape, and WPS nanocrystals were round. This difference in shape is likely due to the different packing configuration of double helices in native starches.

Insights into the multiscale structure and pasting properties of ball-milled waxy maize and waxy rice starches

The effects of ball-milling on the pasting properties of waxy maize starch (WMS) and waxy rice starch (WRS) were investigated from a multiscale structural view. The results confirmed that ball-milling significantly destroyed the structures of the two waxy starches (especially WMS). Specifically, ball-milling led to obvious grooves on the surface of starch granules, a decrease in crystallinity and the degree of short-range order, and a reduction in double-helix components. Meanwhile, small-angle X-ray scattering results indicated that the semicrystalline lamellae of starch were disrupted after ball-milling. Ball-milling decreased the pasting temperatures. Furthermore, ball-milled starches exhibited lower peak and breakdown viscosity and weakened tendency to retrogradation. These results implied that ball-milling induced structural changes in starch that significantly affected its pasting properties. Hence, ball-milled starch may serve as food ingredients with low pasting temperature and paste viscosity as well as high paste stability under heating/cooling and shearing.

Effect of ultrahigh pressure on structural and physicochemical properties of rice and corn starch in complexes with apple polyphenols

BACKGROUND

Ultrahigh-pressure (UHP) treatment, a non-thermal processing technology, exerts a bactericidal effect and affects food texture. How UHP treatments influence starch-polyphenol complexes has not yet been reported. Here, we studied the effects of UHP treatment on the structure of common rice starch (CRS)-apple polyphenol (AP) and common corn starch (CCS)-AP mixtures.

RESULTS

Overall, UHP treatment decreased the particle size of the CRS-AP and CCS-AP composites. Furthermore, the ΔH values of the CRS-AP and CCS-AP mixtures decreased, and the heating stability was improved after UHP treatment. X-ray diffraction indicated that the relative crystallinity of the mixtures was unaffected by UHP treatment. Fourier-transform infrared spectroscopy proved that no new absorption peaks were observed in the infrared spectra, and the order of starch-AP was decreased after UHP treatment. These results indicated that UHP treatment inhibited the retrogradation of the starch-AP mixture. Our analyses of the microstructures of CRS-AP and CCS-AP mixtures showed increased folding and more pronounced network structures under high-pressure.

CONCLUSIONS

These results provide a theoretical basis for further exploring the properties of starch-AP mixtures following UHP treatment and provide insights regarding the use of UHP treatments for food production. © 2020 Society of Chemical Industry.

Production and Properties of Starch Citrates-Current Research

Starch modification by chemical reaction is widely used to improve the properties of native starch. Modified by citric acid, starch is characterized by specific properties resulting from the presence of citrate residues and as a result of cross-linking starch. The chemicals used for preparing starch citrates are safe for human health and the natural environment compared to the harsh chemicals used for conventional modifications. Starch citrates are traditionally produced by heating starch-citric acid mixtures in semi-dry conditions or by a heat moisture treatment. The conditions of the modification process (roasting temperature, heating time, citric acid dose) and the botanic source or genotype of starch determine the degree of substitution and the properties of the obtained preparations. Changes of starch properties occurring during esterification lead to reduced relative crystallinity, resulting in a decrease in the affinity for water, the gelatinization parameters, and the viscosity of starch citrate. However, one of the most important outcome of the modification is the formation of resistant starch (RS), which has increased resistance to the action of amylolytic enzymes. Currently, new methods for producing starch citrates with improved functional and rheological properties while maintaining the highest possible content of resistant starch are being sought. The article presents an overview of recent studies on the production, properties. And applicability of starch citrates with special attention paid to their role as preparations of resistant starch (RS). The use of citric acid for modification of starch is better for the technology process, while using cross-linking is better than simply using esterification.

Impact of static and dynamic modes of semi-dry heat reaction on the characteristics of starch citrates

The objective of this study was to demonstrate the validity of dynamic semi-dry heat reaction (SDHR) by investigating the effects of static and dynamic SDHR on the characteristics of starch citrates. The starch (normal and waxy corn)-citric acid (CA) mixture was heated in a convection oven (static mode) or a twin-screw extruder without a die (dynamic mode). The ester bonds of starch citrates were confirmed by FT-IR, and their molar degree of substitution did not differ between the reaction modes for the tested starch genotypes. Starch citrates by dynamic SDHR exhibited higher relative crystallinity, resistant starch content, solubility, swelling power, and gelatinization compared to those by static SDHR. Although static SDHR did not show a viscosity development during pasting, dynamic SDHR increased their pasting viscosities. Overall, these results suggest that dynamic SDHR could improve the defects (i.e., lack of solubility, swelling, and pasting attributes) of the traditional starch citrates.