Starch-iodine Complex Research Articles

The Waxy Gene Has Pleiotropic Effects on Hot Water-Soluble and -Insoluble Amylose Contents in Rice (Oryza sativa) Grains.

Rice (Oryza sativa) is a cereal crop with a starchy endosperm. Starch is composed of amylose and amylopectin. Amylose content (AC) is the principal determinant of rice quality, but varieties with similar ACs can still vary substantially in their quality. In this study, we analyzed the total AC (TAC) and its constituent fractions, the hot water-soluble amylose content (SAC) and hot water-insoluble amylose content (IAC), in two sets of related chromosome segment substitution lines of rice with a common genetic background grown in two years. We searched for quantitative trait loci (QTLs) associated with SAC, IAC, and TAC and identified one common QTL (qSAC-6, qIAC-6, and qTAC-6) on chromosome 6. Map-based cloning revealed that the gene underlying the trait associated with this common QTL is Waxy (Wx). An analysis of the colors of soluble and insoluble starch-iodine complexes and their λmax values (wavelengths at the positions of their peak absorbance values) as well as gel permeation chromatography revealed that Wx is responsible for the biosynthesis of amylose, comprising a large proportion of the soluble fractions of the SAC. Wx is also involved in the biosynthesis of long chains of amylopectin, comprising the hot water-insoluble fractions of the IAC. These findings highlight the pleiotropic effects of Wx on the SAC and IAC. This pleiotropy indicates that these traits have a positive genetic correlation. Therefore, further studies of rice quality should use rice varieties with the same Wx genotype to eliminate the pleiotropic effects of this gene, allowing the independent relationship between the SAC or IAC and rice quality to be elucidated through a multiple correlation analysis. These findings are applicable to other valuable cereal crops as well.

Antimicrobial Solid Starch-Iodine Complex via Reactive Extrusion and Its Application in PLA-PBAT Blown Films.

In this study, a solid masterbatch of starch-iodine complex with 6.7 wt.% iodine was prepared in pellet form using a ZSK-30 twin-screw extruder. Thermogravimetric (TGA) and isothermal TGA analysis of the pellets revealed that there was no significant loss of iodine due to sublimation during reactive extrusion. These solid pellets demonstrated antifungal properties when applied to strawberries via dip coating in an aqueous solution, extending their shelf life from two days to eight days, thereby reducing fungal growth and visual decay. Furthermore, the solid pellets displayed antibacterial activity against E. coli, as evidenced by the clear zone of inhibition observed in the Kirby-Bauer test. To enhance practical application, these pellets were further blended with PLA-PBAT film formulations at 10 and 18% by wt. to make blown films with effective iodine loadings of 0.7 and 1.3% by wt. These films showed superior antibacterial activity against E. coli compared with PLA control films and the commercial silver antimicrobial-containing films during direct inoculation tests as per ISO 22196. Tensile strength and elongation at break in machine direction (MD) for the starch-iodine-containing blown films were comparable to the control films in MD, but tensile strength was reduced to 37-40% in the transverse direction (TD). This was due to a non-uniform dispersion of the starch-iodine complex in the films, as confirmed by the visual and SEM analyses. Thus, this study illustrates the practical utility of the solid starch-iodine complex as a safe and efficient means of introducing iodine into an environment, mitigating the typical hazards associated with handling solid iodine.

Enhanced fill factor and stability of perovskite solar cells with a multifunctional additive of starch-iodine complex

The efficiency and stability of perovskite solar cells (PSCs) can be greatly affected by various factors such as passivating the perovskite film, oxidizing the hole-transport material of 2,2′,7,7′-tetras(N,N-p-methoxyaniline)-9,9′-spirodifluorene (Spiro-OMeTAD), and inhibiting the iodide migration. Here we introduce a multifunctional starch-iodine complex in the perovskite film to enhance the fill factor and stability of PSCs. Results demonstrate that the starch-iodine complex from the perovskite film can release iodine molecules to gently oxidize the Spiro-OMeTAD, which can significantly increase the PSC's fill factor. Moreover, the remaining starch can effectively passivate the perovskite film to obviously improve the PSC's long-term stability. Furthermore, the starch-iodine complex can absorb and store the iodide ions to generate a starch-triiodide complex, which can release iodide ions to promote iodide defect self-healing and suppress iodide migration in the perovskite films, resulting in a further enhancement of the PSC's long-term stability. As a result, the PSC based on the starch-iodine complex obtains a superior cell efficiency of 22.60% with a high fill factor of 79.54%, and keeps 91.12% of its original efficiency after 1500 h.

Artificial saliva induced structural breakdown of surimi gels with starch under continuous compressive motions

Food texture perception is dynamic, influenced by food properties and oral processing. Using the Repeatable Dual Extrusion Cell (RDEC), the oral processing dynamics of surimi gel with different corn starch concentrations (0–15%) in the presence of 1 ml artificial saliva or water were studied. The force-time curve showed increased peak forces with higher corn starch concentrations, peaking significantly at 10%, then decreasing at 15%. Salivary amylase played a crucial role in gel sample degradation, especially in samples with 5% starch, with a work value depletion ratio of 0.535 for sample with 1 ml water (SGW-5) and 0.406 for sample with 1 ml saliva (SGS-5). SEM analysis confirmed the formation of a continuous starch network with reduced intermolecular spaces in SGS-5. The starch-iodine complex showed decreasing order with increasing starch concentration, and SGS-5 exhibited the highest degradation rate (61.61 ± 0.92%). Mathematical modeling revealed that initial decay rates (k1) in gel sample decreased with increasing starch concentration, and samples with starch and artificial saliva had higher initial degradation rates. These findings highlight the intricate interplay between saliva and starch in the surimi gel matrix under continuous compressive motions by RDEC apparatus, providing insights for formulating food products with tailored textures properties.

A facile double moving redox boundary model for visual electrophoresis titration of ascorbic acid.

In this work, we proposed a double moving redox boundary (MROB) model to realize the colorless analyte electrophoresis titration (ET) by the two steps of the redox reaction. Single MROB has been proposed for the development of ET sensing (Analyst, 2013, 138, 1137. ACS Sensor, 2019, 4, 126.), and faces great challenges in detecting the analyte without color change during redox reaction. Herein, a novel model of double-MROB electrophoresis, including its mechanisms, equations, and procedures, was developed for titration by using ascorbic acid as a model analyte. The first MROB was created with ferric iron (Fe3+) and iodide ion (I-) in which Fe3+ was reduced as Fe2+ and I- was oxidized as molecular iodine (I2) used as an indicator of visible MROB due to blue starch-iodine complex. The second boundary was then formed between the molecular iodine and model analyte of ascorbic acid. Under given conditions, there was a quantitative relationship between velocity of MROB (VMROB(ii)) and ascorbic acid concentration (CVit C) in the double-MROB system (1/VMROB(ii)=0.6502CVit C+4.5165, and R=0.9939). The relevant relative standard deviation values of intraday and inter-day were less than ∼5.55% and ∼6.64%, respectively. Finally, the titration of ascorbic acid in chewable vitamin C tablets was performed by the developed method, the titration results agreed with those via the classic iodometric titration. All the results briefly demonstrated the validity of the double MROB model, in which Vit C was used as a model analyte. The developed method had potential use in quantitative analysis of redox-active species in biomedical samples.

On the Origin of the Blue Color in The Iodine/Iodide/Starch Supramolecular Complex.

The nature of the blue color in the iodine-starch reaction is still a matter of debate. Some textbooks still invoke charge-transfer bands within a chain of neutral I2 molecules inside the hydrophobic channel defined by the interior of the amylose helical structure. However, the consensus is that the interior of the helix is not altogether hydrophobic-and that a mixture of I2 molecules and iodide anions reside there and are responsible for the intense charge-transfer bands that yield the blue color of the "iodine-starch complex". Indeed, iodide is a prerequisite of the reaction. However, some debate still exists regarding the nature of the iodine-iodine units inside the amylose helix. Species such as I3-, I5-, I7- etc. have been invoked. Here, we report UV-vis titration data and computational simulations using density functional theory (DFT) for the iodine/iodide chains as well as semiempirical (AM1, PM3) calculations of the amylose-iodine/iodide complexes, that (1) confirm that iodide is a pre-requisite for blue color formation in the iodine-starch system, (2) propose the nature of the complex to involve alternating sets of I2 and Ix- units, and (3) identify the nature of the charge-transfer bands as involving transfer from the Ix- σ* orbitals (HOMO) to I2 σ* LUMO orbitals. The best candidate for the "blue complex", based on DFT geometry optimizations and TD-DFT spectral simulations, is an I2-I5-I2 unit, which is expected to occur in a repetitive manner inside the amylose helix.

Double safety guarantees: Food-grade photothermal complex with a pH-triggered NIR absorption from zero to one

Photothermal therapy has aroused great attention and showed promising potential in minimally invasive tumor ablation, but the clinical translation is still stifled by the concerns of unwanted injury to normal tissues. The safety concerns might be completely solved only when the two security obstacles of “material-toxicity” and “photo-toxicity” were overcome simultaneously. Herein, a completely non-toxic food-grade photothermal transduction agent (PTA) with double safety guarantees was invented, which shows an absolute transformation of the photothermal effect from “0” to “1” after being triggered by an acidic tumor microenvironment. Inspired by the classical starch-iodine test, a preprogrammed [starch-KI-KIO3] complex was prepared in large quantities through a modified wet-milling procedure. It's demonstrated that a macroscopic consecutive reaction could be triggered by low pH to produce the starch-iodine complex which can generate lethal temperature under the near-infrared light irradiation. Meanwhile, the PTA shows excellent biocompatibility with no “material-toxicity” owing to the raw materials drawn from our daily food. Animal experiments reveal that the tumor microenvironment can activate the switch of photothermal effect from “0” to “1” successfully, which is thus responsible for the discriminative photo-damage to the tumor region while no “photo-toxicity” to normal tissue. The good treatment efficacy confirms the feasibility of such photothermal transduction agents with double safety guarantees in clinical applications.

Adsorption of Aqueous Iodide on Hexadecyl Pyridinium-Modified Bentonite Investigated Using an Iodine–Starch Complex

The sorption affinity of iodide on organo-bentonite, modified with hexadecyl pyridinium (HDPy), was investigated with the iodine–starch method coupled with UV/Vis absorption spectroscopy. The iodine–starch complex method was optimized in terms of the reaction time and sample compositions, based on the UV/Vis absorbance. The batch sorption experiment for iodide on organo-bentonites, modified using two different loading amounts of HDPy, was conducted to analyze the influence of equilibrium time, liquid-to-solid ratio, and temperature, on the iodide sorption affinity. The experimental results regarding the removal capacity were further employed to derive the distribution coefficients of iodide on the organo-bentonites. The novelty of this work lies in the first application of the iodine–starch method coupled with UV/Vis absorption spectroscopy for analyzing the sorption behavior of iodide on modified bentonites. It is expected that the iodide-starch method can be complementarily employed for future research, with respect to the quantification of iodide.

Indirect spectrophotometric determination of aqueous ferrate(VI) based on its reaction with iodide in acidic media

Ferrate(VI) (Fe(VI)) is utilized as an efficient and environmentally friendly water treatment agent that can be widely used for degradation of (in)organic pollutants in practical applications. However, only a few spectrophotometric methods for Fe(VI) determination were reported. In this study, a novel method for determining trace levels of aqueous Fe(VI) was developed based on the fact that Fe(VI) reacts with iodide at acidic pH to form iodine, which subsequently is treated with starch to yield the blue starch-iodine complex measured spectrophotometrically at 590 nm. The key measurement parameters, including acidic medium, starch dosages, temperature, time, and addition order were optimized to improve the sensitivity of detection. The increase in absorbance at 590 nm was linear with respect to Fe(VI) added (0.022–50 µM). Its sensitivity was determined as (4.61 ± 0.05) × 104 M−1 cm−1, which was higher than that of existing spectrophotometric methods. The principle for Fe(VI) determination was studied by investigating stoichiometry, kinetics, and mechanism of Fe(VI) reaction with iodide. The molar stoichiometry of Fe(VI) with I3− species was determined to be 1:2. The reaction of Fe(VI) with iodide followed a second-order rate law with first order in each reactant and displayed apparent anti-Arrhenius kinetics, then its reaction pathway was proposed as well. Furthermore, the established method was successfully applied to measure Fe(VI) in various environmental water samples. The results show that the proposed approach is simple, convenient, highly reproducible and extremely sensitive, and is also expected to be of use for kinetic studies of Fe(VI) reaction with (in)organic compounds under acidic conditions.

Antimicrobial Activity of Polysorbate 80-iodine Complex: Polysorbate 80 Firmly Retains Iodine.

Considering that iodine is highly volatile and has low solubility in water, it is utilized as an antiseptic in its complex form (iodophor) with a carrier material. Herein, we prepared the polysorbate 80-iodine complex and investigated its properties. In the presence of 0%, 0.01%, 0.1%, and 1% polysorbate, Pseudomonas putida NBRC 100650 growth was inhibited at 75, 75, 50, and 25 ppm iodine, respectively, indicating that high concentrations of polysorbate 80 enhanced the antibacterial activity of iodine. Absorption spectra of the mixtures of polysorbate 80 and iodine were analyzed; we observed that two peaks at 287 and 350 nm, derived from triiodide ions, shifted to the longer wavelength side in the presence of 0.1% and 1% polysorbate 80. Further, when 1% polysorbate 80 was added to the mixture of soluble starch and iodine, the peak around 580 nm arising from the amylose-iodine complex disappeared, indicating that polysorbate 80 captured iodine from the starch-iodine complex. We also found that polysorbate 80 retained iodine for approximately 4 months and prevented its volatilization; moreover, the mixture did not lose its growth inhibitory activity upon storage for approximately 4 months. Collectively, our data indicated that polysorbate 80 firmly retains low concentrations of iodine and that the polysorbate 80-iodine complex can serve as an antiseptic that can be stably stored for a long time.

Probing the Role of the Solvation Shell for the Iodine–Starch Complex Using Millifluidic Devices

Probing the Role of the Solvation Shell for the Iodine–Starch Complex Using Millifluidic Devices

Degree-Based Topological Indices of Polysaccharides: Amylose and Blue Starch-Iodine Complex

Starch is a polymer of glucose where alpha-linkages are associated with glucopyranose units. It comprises a mixture of amylose and amylopectin. Furthermore, amylose is a linear chain of hundreds of glucose molecules. Starches are not allowed to be dissolved in water. They can be digested by breaking down alpha bonds (glycosidic bonds). Its cyclic degradation products, called cyclodextrins, are the best role models for amylose. They can be considered simple turns of the amylose propeller that has imploded into a circular path. Both humans and animals have amylases, which allow them to digest starches. The important sources of starch include potatoes, rice, wheat, and maize for human consumption. The production of starches is how plants store glucose. The blue colour of starch produced by an iodine solution or iodine reaction is used for its identification. Polysaccharides with a reduced degree of polymerization, known as dextrins, are produced in the starch’s partial acid hydrolysis. Complete hydrolysis leads to glucose. In this article, we compute the topological properties: Zagreb index M 1 Γ and M 2 Γ , Randić index R α Γ for α = − 1 / 2 , − 1 , 1 / 2 , 1 , atom-bond connectivity index ABC Γ , geometric-arithmetic index GA Γ , fourth atom-bond connectivity index ABC 4 Γ , fifth geometric-arithmetic index GA 5 Γ , and degree-based topological indices of a graph Γ representing polysaccharides, namely, amylose and blue starch-iodine complex. In the end, we compare these indices and depict their graphic behavior.

Analysis of Iodine Level (KIO3) based on the Formation of Amylum-Iodine Complex using UV-Vis Spectroscopy

Iodine is an important component that needed by the body in the synthesis of thyroid hormones in order to maximize humans’ growth and development. Besides, iodine also plays a role in the regulation and metabolism system in the human body. Iodine Deficiency Disorders (IDD) is one of the nutritional problems which is an inhibiting factor in the development of human resources because it can cause disruption of mental development and human intelligence. Iodine in food is found from table salt, it found in the form of KIO3 with a standard level of iodine in table salt that is 30ppm-80ppm. This research aims to determine the iodine levels in the four kinds of table salt using spectrophotometric methods based on the formation of the starch iodine complex. The formation of the starch iodine complex performed by reacting I- with the oxidizer IO3- in an acidic atmosphere with starch indicator. The resulting blue color was analysed by visible spectrophotometry and produce absorbance data. The measured iodine content is equal to samples A, B, C, and D showing results less than 30 ppm so it can be concluded that iodine in table salt still does not meet the SNI standards that should be around 30ppm-80ppm

α-Amylase assay with starch–iodine–sodium fluorescein-based fluorometric method in human serum samples

A new fluorometric method was developed for the determination of α-amylase activity in human serum samples. Firstly, a saturated starch–iodine complex (SI) was prepared. The SI complex was combined with sodium fluorescein to form a starch–iodine–sodium fluorescein complex (SIF). As the SIF complex decomposes with the α-amylase enzymatic hydrolysis of starch, the intensity of its fluorescence emission increases. The α-amylase activity is determined using the increased fluorescence emission intensity following hydrolysis of the SIF complex by α-amylase. The optimum pH, optimum buffer concentration, optimum temperature, and interference effect were identified for the developed fluorometric measurement method. Under the optimum conditions, a linear calibration curve was obtained between 0.18 and 9.00 U/L for α-amylase. The α-amylase activity in the human serum sample was also determined by our prepared measurement system and compared with the result from a medical center. Both methods are in good agreement with each other. Because this newly developed fluorometric method for α-amylase activity in serum samples is inexpensive, easy to use, and carried out to detect a very low amount of human serum α-amylase with sensitivity, it can be proposed this method for alpha-amylase activity assay in all other biological samples.

Molecular self-assembly of 1D infinite polyiodide helices in a phenanthrolinium salt.

A new linear polymeric polyiodide, catena-poly[tris(1,10-phenanthrolin-1-ium)tris(1,10-phenanthroline)heptaiodide], was prepared by one-step synthesis. Its formation is driven by hydrogen-bond assisted supramolecular assembly in the presence of chromium(iii) acetate. Its structure has been characterized by the means of single-crystal X-ray diffraction. To date, this is only one of the few examples of organized linear infinite polyiodides with a known structure. The interplay between the interactions within the hypervalent iodine chain and its supramolecular environment is elucidated. The electrical, thermal, and spectroscopic properties of the studied compound were investigated and associated with the structural features. The infinite character of the polyiodide chain and its similarity to the blue starch-iodine complex has been additionally confirmed by Raman spectroscopy. Despite the apparent structural and spectroscopic similarities with the previously reported 1D polymeric polyiodide, its physical properties, i.e. electrical conductivity and thermal stability, differ significantly. This can be rationalized by the differences in the orbital overlap within the iodine chain, as well as the distinct interactions with the cation.

Titrimetric and Spectrophotometric Determination of Some Thiadiazole Derivatives by Using Amplification Reactions

The principle of using amplification reactions of iodine was employed in this paper to estimate the thiadiazole derivatives on basis of their reactions with iodine I chloroform, removal of the excess iodine and determination of the resulting iodide, after oxidation to iodate. The overall reaction gave an amplification of the iodide that is (12) times larger for the compounds: 2-amino-5-mercapto-1,3,4-thiadiazole (I); 2,5-dimercapto-1,3,4-thiadiaole (II) and 2,5-diamino-1,3,4-thiadiazole (III) and (36) times for 2,5-dihydrazino-1,3,4-thiadiazole (IV) and (6) times for 5-mercapto-2[(3[5’-nitro-2-’furyl]·methylene)amino]-1,3,4-thiadiazole (V) and 5-mercapto-2[(3[5’-nitro-2-’furyl]-prop-2-enylidene)amino]-1,3,4-thiadiazole (VI). By titration, 1-mL of standard thiosulfate solution was found equivalent to 0.108 mg of (I); 0.126 mg of (II), 0.16 mg of (III), 0.041 mg of (IV), 0.40 mg of (V) and 0.435 mg of (VI). Using the spectrophotometric detection for the amplification reaction gave high absorbance values at 605 nm for the blue starch-iodine complex. Beer’s law was obeyed up to 4.0 ppm for compounds (I and II); 6.0 ppm for compounds (III, IV and VI) and 5.0 ppm for compound (V). The mechanism of the reactions was proposed and the analytical parameters were evaluated for both methods. The method was applied for synthetic samples of industrial importance. The recovery was comparable while the sensitivity and detection limits were better for the spectrophotometric detection.

South Ural State University, Chelyabinsk, Russian Federation

A method for the kinetic photometric determination of oxalate ion in aqueous solutions, in-cluding extracts from foodstuffs, has been suggested. The initial rate method has been used: the straight parts of kinetic curves (approximately 5 min) are processed by the least square method to get the slope coefficients used as analytical signals. The procedure is based upon the oxalate ion action as an activator in the iron(II)-catalyzed reaction of iodide oxidation by potassium bromate. Unlike the previously used light absorbance in the UV region, the suggested procedure controls the rate of the iodine-starch complex formation at 590 nm. The greatest initial rate for the reaction is at pH 5.05 of the acetate buffer solution and the optimal concentration of soluble starch 0.30 mg/mL. The calibration graph is linear in the oxalate concentration range (0.1–10) mg/mL. In this interval precision error varies between 0.67 % and 4.71 %, accuracy error is within (0.22–9.30) %. The procedure has been applied to food analysis by the standard addition method. Aqueous extract has been obtained from 2.5 g of finely chopped sample of raw beet, stirred with 100 mL of water for 1 h, centrifuged, filtered, and quantitatively transferred to 250-mL volumetric flask. Determination of oxalate in 1-mL aliquot has required the same volume of colored beet extract for a reference solution, but otherwise the procedure stands valid. The oxalate content has been found to equal (379 ± 2) mg/g of the raw beet (P = 0,95; n = 4), with 0.6 % precision error and 3.0 % accuracy error.

Interactions between caffeic acid and corn starch with varying amylose content and their effects on starch digestion

This study aimed to evaluate the physical-chemical interaction between caffeic acid (CA) and gelatinized corn starch with varying amylose and its potential effect on starch digestion. Iodine binding reaction indicated that the absorbance of starch-iodine complex was lower than that in the starch-CA sample. Furthermore, the decrease of absorbance in high amylose corn starch was the most obvious. The affinity constant for CA obtained by isothermal titration calorimetry analysis increased with the amylose content. In the 1H NMR analysis, the peaks of starch hydroxyl groups at 5.4 and 5.5 ppm became broader after the addition of CA, demonstrating that CA interacted with the selected starches via the hydroxyl groups to form hydrogen bonds. In vitro digestibility studies revealed that the interaction between CA and starch had different effects on starch with different amylose content. Moreover, it was revealed that 2% of CA promoted the hydrolytic process, but a drastic reduction of the hydrolytic process occurred upon increasing the CA to 10% for CS. These results suggested that amylose content and certain interactions with CA was a potential reason affecting the mode of interaction, thus altering the digestion.

Reliability factor for identification of amylolytic enzyme activity in the optimized starch-iodine assay

Amylolytic enzymes are a group of proteins degrading starch to its constitutional units. For high-throughput screening, simple yet accurate methods in addition to the reducing ends assays are required. In this article, the iodine assay, a photometric assay based on the intensely colored starch-iodine complex, was adapted to enable accurate and objective differentiation between enzyme and background activity using a newly introduced mathematical factor. The method was further improved by designing a simple setup for multiple time point detection and discussing the applicability of single wavelength measurements.

Some physicochemical properties of tapioca starch during infrared heat treatment

Applying infrared radiation heat treatment is an alternative production process of modified starch. The infrared radiation heat treatment for modifying tapioca starch was set at 170, 190 and 210°C. The properties of starch including swelling power, total color difference and blue value were determined every 2 h until 20 h of heating. The results showed that increasing the heating temperature and time decreased the blue value of starch-iodine complex. Meanwhile, the swelling power and total color difference increased with the heating temperature and time.