Mixture Ratio Research Articles

Determination of 3-acetyl-11-keto-β-boswellic acid in analytical and biological samples using streamlined and robust RP-HPLC method.

AKBA (3-acetyl-11-keto-β-boswellic acid) is a phytoconstituent derived from Boswellia serrata extract and utilized in the management of rheumatoid arthritis. Drug delivery approaches showed interest in delivering AKBA with advanced nanotechnology. There is a need for a simple, sensitive, and robust HPLC method that can determine AKBA in complex nanoformulation and in vitro and ex vivo samples. In the proposed work, the RP-HPLC method was developed using a mobile phase comprising a mixture of acetonitrile : milli Q (90 : 10) at detection λmax 250 nm. The method exhibited a linearity of 250 to 20 000 ng mL-1 with a high correlation coefficient of 1. The limit of detection and limit of quantification for the analytes were found to be 41.32 ng mL-1 and 125.21 ng mL-1, respectively. In the accuracy study, the % recovery of AKBA was found to be 98% to 102%, and the precision study showed less than 2% relative standard deviation. The developed method was found to be robust under chromatographic conditions with changes in pH and mobile phase mixture ratio. The method was also explored for forced degradation study, and the results showed the successful separation of degradation products from the AKBA. Further, the RP-HPLC method was applied for the quantification of AKBA in topical nanoformulations and different matrices, such as skin matrices and adhesive tapes. The method was able to measure entrapment efficiency (93.13 ± 1.94%), drug loading (25.83 ± 0.54%), drug assay in a gel matrix (96.99 ± 3.89%), drug amount in stratum corneum (7.90 ± 0.62 μg cm-2), and drug amount in viable skin layers (33.94 ± 0.21 μg cm-2) with high-speed reproducibility. The developed method can be utilized for the routine analysis of AKBA in conventional and complex formulations in academia and industry.

Elucidating Synergetic Effects of Anaerobic Co-Digestion of Slaughterhouse Waste with Livestock Manures

This study quantitatively analyzed the synergistic effects of co-digestion of slaughterhouse waste (SHW) with cattle manure (CM) and pig manure (PM) on methane production by applying statistical methods. The biochemical methane potential of volatile solid concentration-based mixtures showed that the biodegradability (BD) of the co-substrates was improved as the mixing proportion of the highly biodegradable SHW increased. Furthermore, mathematical analysis using the modified Gompertz model showed that an increase in the SHW mixture ratio shortened the lag phase at the initial period by more than 58%. The synergy index (SI) analysis revealed that co-digestion of CM and SHW mixed at an equal ratio of 1:1 in sample S4 resulted in a higher SI of 1.18 compared to 1.10 for PM and SHW in sample S5. An overlay plot based on BD and SI identified the optimal mixture ratio as 26.9:31.0:42.1 (CM/PM/SHW), where both BD and SI reached their maximum values. The study successfully demonstrated that co-digestion of SHW with livestock manure enhances BD through a synergistic effect.

Bimetallic Ln-MOF nanofibrous membrane as colorimetric fluorescent test strip for 1, 4-dioxane-glycol mixture ratio sensing

A bimetallic Ln-MOF nanofibrous membrane (NFM) was successfully fabricated by in situ growth of Eu/Tb-MOF crystals onto electrospun polycaprolactam (PA6) nanofibers. For better combining with PA6 nanofibers, the Eu/Tb-MOFs were made into nanocrystals. Characterization with PXRD, FT-IR, EDS and XPS confirmed that the crystal structure of the Eu/Tb-MOFs maintained well on PA6 NFM. The as-prepared Eu/Tb-MOF@PA6 NFM can be used as a colorimetric fluorescent test strip for instant detection of the volume ratio of 1, 4-dioxane in 1, 4-dioxane-glycol mixture. With the increase of 1, 4-dioxane, the test strip presented color changes from green to red, which can be easily distinguished by the naked eye. In view of this, the conversion rate of the condensation reaction of glycol to 1, 4-dioxane will be preliminarily estimated without the help of equipment. More importantly, the test strip exhibited better convenience and reversibility compared with powdered Ln-MOFs because no separation process was needed for test strip before and after recovering. Benefiting from sufficient amide groups in PA6 for anchoring Eu/Tb-MOF particles, the test strip showed satisfactory stability in cycling experiments. This work will provide a new insight into the development of fluorescent test strip based on electrospun MOF NFM for quantitatively monitoring the reaction process.

ANAEROBIC CO-DIGESTION OF DIFFERENT MIXTURES OF ORGANIC WASTES – OUR EXPERIENCE

Anaerobic digestion is a biotechnological method of biogas generation from organic wastes. Anaerobic co-digestion can be considered as the instantaneous anaerobic digestion of two or more substrate and co-substrate mixtures. Anaerobic co-digestion is a pragmatic method to resolve the difficulties related to substrate properties and system optimization in single-substrate anaerobic digestion. During the last two decades our multidisciplinary team performed a lot of experiments of anaerobic co-digestion of different organic wastes activated sludge, cattle manure, swine manure, milk whey, wasted fruits and vegetables etc. Different ratios of mixtures of these organic wastes, in binary and triple mixtures, have been investigated in view to maximize the obtained energy (methane) production. The time for reaching of the process steady state in laboratory anaerobic digesters have been determined to be ten days’ period. Results obtained have shown that some binary mixtures are more perspective in regards to biogas production optimization. It has been found that the addition of 3rd substrate to some binary mixtures could lead to decrease of bioprocess effectiveness.

Exergy-water nexus of a multi-energy complementary trigeneration system with different fuel mixture ratios

Complex coupling relationships of energy, exergy and water streams in multi-energy complementary systems due to different characteristics of energy flows are necessarily revealed to determine the intensities of downstream products. This paper proposes a multi-energy complementary trigeneration system driven by biomass, solar energy, and natural gas to generate cooling, heating, and power products. An exergy-water analysis approach, considering energy levels of streams, is adopted to determine the exergy and water footprint intensities per unit energy products. A life cycle assessment method is used to calculate the water footprint of biomass and natural gas as the primary energy sources. The relationship between the exergy and water footprint intensity of the system equipment and output products is presented and discussed with the mixture ratios of natural gas and biomass product gas. Furthermore, the cumulative exergy and water footprint intensity of products are analyzed under different system working conditions, such as mixture ratio of biomass and natural gas and the solar irradiance. When the same mixture volume gas fuels drive the trigeneration system, the overall exergy efficiency is 25.38 % while the efficiency including the upstream cumulative exergy destruction is only 21.93 %. The unit water footprint intensities of power and cooling products based on exergy measurement are 7.12 kg/kWh and 36.32 kg/kWh, respectively. The exergy-water footprint sensitivity of biomass and natural gas on system product intensities are implemented to consider the uncertain variables. When the mixture ratio increases from 0 to 1, the cumulative exergy destruction of system power is declined by 35.62 % under the uncertain ranges of ±50 %. Also, its water footprint is declined by 91.62 %. The proposed model provides an effective tool to reveal the exergy-water nexus and determine the intensities of multi-energy products.

Determination of chemical elements of barley and teff using flame atomic absorption spectroscopy (FAAS)

Metallic elemental analyses are needed to complete food composition databases, in which humans consume food to obtain energy and be able to do everyday work. The study aimed to investigate the concentrations of some metals (K, Al, Fe, Cu, Cd, and Pb) in teff and barley samples using flame atomic absorption spectroscopy (FAAS) techniques. The samples, weighing 0.5 grams each, were subjected to wet digestions using a mixture ratio of 7:3(vol/vol) of HNO3 to H2O2 reagents at 90°c for 3:00 h under optimal conditions. The reagents were used to digest food samples for the presence of specific metallic elements. Flame Atomic Absorption Spectroscopy (FAAS) was used to analyze the mineral contents of the digested samples. The results demonstrated that the relative concentrations obtained in these cereal crops are different from one another. The concentration of metallic elements in mg/kg of K (2709.6±3.3), Al (952.3±4.2), Fe (320.9±4.8), Cu (25.3±3.2), Pb (ND) and Cd (ND) for red teff, K (3053.7±1.6), Al (1095.2±4.2), Fe (271.6±4.8), Cu (60.1±3.2), Pb (ND) and Cd (ND) for white teff while K (4333.3±3.2), Al (2595.2±4.2), Fe (74.0±0.00), Cu (10.5±1.8), Pb (ND) and Cd (ND) for barley. The high content of potassium and aluminum metallic elements was found in barley cereals. The results of this study will be useful in enriching the database of Ethiopian cereals as foods, advancing the knowledge of cereals and deepening the scientific understanding of the cereals.

Liquid Phase Parameter Analysis of Methanogenesis in Anaerobic Digestion of Coal Promoted by Kitchen Waste

In order to study the effect of food and kitchen waste on promoting methane production by collaborative fermentation of coal, this paper selected lignite and food and kitchen waste as the research objects, and carried out the gas production experiment of mixed fermentation of coal and food and kitchen waste with different ratios at 35 ℃ with mine water as the bacteria source. The results showed that the cumulative CH4 production was the highest in the mixed fermentation with the ratio of 1:4 (coal: kitchen waste). Therefore, exploring the optimal mixture ratio of coal and food waste fermentation can not only effectively improve the gas production effect, but also broaden the diversified utilization ways of coal and food waste, which has a good development potential.

Effects of Different Mixture Rate of Common Vetch (Vicia Sativa L.) and Ryegrass (Lolium Multiflorum l.) on Quality

This research was established in order to determine the quality characteristics of common vetch and ryegrass by testing different mixture ratios in different locations and to measure the effects of mixing ratios. Aneto common vetch and Trinova ryegrass cultivars were used in the trials. The experiment was carried out in the locations of Manisa/Beydere and Ankara/Yenikent in the vegetation period of 2021-2022 according to the randomized blocks trial design. The highest crude protein ratio was obtained from the 100% V mixture with a value of 20.4% from the Manisa location. The lowest crude protein ratio was obtained from the Ankara location with a value of 11.1% from the 100% G mixture. As a result of this study, it was found that the legume and grass forage crops planted as a mixture were better for interrestrial and coastal regions in terms of quality compared to pure stand growing. In fact, it has been determined that forage crops planted as a mixture are more advantageous in terms of quality since they are more resistant to lodging than pure legume stands.

Long-term and accelerated swelling of steel slag-glass powder and steel slag-fly ash mixtures as sustainable geo-materials

The volumetric instability of steel slag hinders its use in pavement layers and embankments. Accordingly, evaluating the swelling potential of steel slag and designing volumetrically stable steel slag mixtures is required to promote its sustainable utilization. This paper focuses on the comparison of the swelling response of basic-oxygen-furnace steel slag (BOFS), electric-arc-furnace steel slag (EAFS), BOFS-fly ash and BOFS-glass powder mixtures based on the results of three different types of tests: (i) long-term California bearing ratio (CBR) swelling, (ii) heated water bath swelling and (iii) autoclave tests. BOFS mixtures were prepared using glass powder or class F fly ash with 5%, 10%, and 20% replacement ratios. The compaction characteristics, permeability, and California bearing ratio (CBR) of steel slag and steel slag mixtures were also assessed within the framework of a detailed discussion of their swelling response. At the end of swelling tests, the measured maximum 1D strains of EAFS were all at negligible levels. Based on the test results, BOFS and BOFS-glass powder mixtures had ∼5.0–5.5% swelling strains after 20.5 months without signs of stabilization. 20% class F fly ash replacement stabilized the swelling strains of the mixture at about 0.75% after ∼3 months of monitoring in long-term tests. 1D swelling rates measured for all BOFS-class F fly ash mixtures decreased with increasing fly ash content. CBR and swelling response of BOFS-class F fly ash mixtures were more favorable compared to those of BOFS. The heated water bath tests provided higher estimates of the swelling strains compared to those obtained from autoclave tests for the steel slag mixtures that contain 15% or more fines. The results of this study showed that glass powder replacement is not effective in alleviating the swelling of BOFS. The volumetrically stable BOFS-class F fly ash mixtures indicated favorable mechanical properties for their use in pavement layers.

Development and performance evaluation of paddy straw based insulating block composite for low temperature storage application

The study focuses on the conversion of crop residues into thermal insulation materials, to gain better utility with value addition. Such applications will divert the paddy straw to useful purposes, leading to reduction in the open field burning of paddy straw in various developing countries. The process was optimized for manufacturing of insulating block composite and evaluating the mechanical and thermal performance of the same. Properties like compressive strength, internal bonding strength, density, porosity, and thermal conductivity were studied for the block. The optimum physical and mechanical properties were observed as moisture content 8–10 %, a block density 450–500 kg/m3, porosity 70 % with particle size of 8–15 mm. The mixture ratio of block was optimized as paddy straw 574.9 g, clay 840 g, and seed lac 260 g with thermal conductivity, compressive strength, bonding strength, and porosity as 0.08 W/m K, 1.19 MPa, 0.028 MPa, and 70.7 %, respectively, using Response Surface Methodology. An eco-friendly, economical and sustainable technological value addition for paddy straw was obtained and used for insulation purposes in cold storages as well as drying chambers. Paddy straw insulating block can also be utilized in combination with conventional insulation materials.

Spray combustion characteristics and soot formation potential of Nano-Al2O3 diesel at low ambient temperatures

Nanoparticle additives have the potential to enhance combustion efficiency and reduce emissions in liquid combustion processes. This study thoroughly investigates the spray evaporation, ignition, and combustion characteristics of nanoparticle/fuel blends, especially under challenging environmental conditions, to improve combustion efficiency and reduce emissions. Employing diffused background illumination, shadowgraph, Mie scattering, high-speed natural luminosity, and two-color method, the spray combustion dynamics of thermally stable nano-Al2O3/diesel (NAD) blends were examined within a constant volume combustion chamber. Diesel, a prevalent primary or auxiliary fuel, represents other highly volatile renewable fuels, while Al2O3, a significant component in combustion fly ash, is noted for its specific catalytic properties and ability to re-burn, eliminating organic toxic elements. The results indicated that NAD blends exhibit a faster evolution rate for both liquid and vapor sprays compared to pure diesel, attributed to the increased kinetic energy of breakup droplets. Under most experimental conditions, incorporation of nano-Al2O3 slightly reduced the ignition delay time due to enhanced heat transfer. Notably, nano-Al2O3 altered the ignition mechanism of the diesel spray, transitioning it from partially premixed to diffusion combustion and relocating the ignition point nearer to the injector. The combustion flame of NAD blends demonstrated increased luminosity, a shorter flame lift-off length, and variations in start-of-injection and total-injection-nozzle-lift-off. However, due to a high equivalence ratio mixture between the liquid phase spray and combustion region, the soot concentration in NAD blends was higher than that in diesel. Additionally, the elevated flame temperature in NAD blends significantly increased the soot concentration. Overall, nano-Al2O3 markedly enhances diesel combustion, especially in low ambient temperatures, suggesting its impressive potential for the high-efficiency and low-emission utilization of renewable fuels or the combustion of recycled waste solvents.

The effect of different powder mixtures used in the boriding process on the surface properties of AISI 304 stainless steel material

AISI 304 stainless steel, which is used in many areas such as chemistry, petrochemistry, storage tanks and food storage, attracts attention in terms of surface hardness and wear resistance, especially when its industrial applications are evaluated. In this study, it was aimed to improve the surface properties of the AISI 304 stainless steel material used as the substrate material. To develop the best surface properties, boriding layers of varying percentages were created. In order to create these layers, B4C, KBF4, SiC and graphite powders were compared using variable ratios. Microhardness and wear tests were performed on the borided samples and microstructure examinations were carried out using optical, SEM, XRD and EDX. It has been determined that the B4C used as boron source should not be less than 20% for the formation of the boriding layer and the double phase FeB/Fe2B. The powder mixture ratio with the highest thickness and hardness value of the boriding layer formed is the powder mixture with 20% B4C, 50% KBF4, 10% SiC and 20% graphite content. It was observed that the layer thickness increased by 63% and the hardness value increased by 11%. It was observed that this powder mixture gave the lowest wear rate compared to the other powder mixtures in the study. The difference between the highest and lowest wear rate is more than 3 times greater.

Multi-response optimization of charcoal briquettes process for green economy using a novel TOPSIS linear programming and genetic algorithms based on response surface methodology

The production of charcoal briquettes was based on the concept of utilizing waste for sustainable and eco-friendly solutions within the green economy. This study introduces a new approach for optimizing important properties of charcoal briquettes. The approach aims to determine the appropriate operating conditions using a hybrid method. It integrates a novel TOPSIS linear programming with genetic algorithms based on response surface methodology. The experiment used an optimal mixture ratio of 25:10:6, including coconut shell, bagasse ash, and corncob. The results of the responses showed increased heating value and burning time by 5.13 % and 5.71 %, respectively, and moisture content decreased by 15.12 %. Furthermore, confirmation experiments within a 95 % confidence interval verified that the three responses obtained at the optimal operating conditions of process factors. The total cost of charcoal briquettes is 0.903 USD/kg and a payback period of 4.85 years. This illustrates that process improvement also aligns with the broader goals of promoting green and a circular economy.

Performance and protein conformation of thermally treated silver carp (Hypophthalmichthys molitrix) and scallop (Argopecten irradians) blended gels.

The quality of surimi-based products can be improved by combining the flesh of different aquatic organisms. The present study investigated the effects of incorporating diverse ratios of unwashed silver carp (H) and scallop (A) and using various thermal treatments on the moisture, texture, microstructure, and conformation of the blended gels and myofibrillar protein of surimi. A mixture ratio of A:H = 1:3 yielded the highest gel strength, which was 60.4% higher than that of scallop gel. The cooking losses of high-pressure heating and water-bath microwaving were significantly higher than those of other methods (P < 0.05). Moreover, the two-step water bath and water-bath microwaving samples exhibited a more regular spatial network structure compared to other samples. The mixed samples exhibited a microstructure with a uniform and ordered spatial network, allowing more free water to be trapped by the internal structure, resulting in more favorable gel properties. The thermal treatments comprehensively modified the tertiary and quaternary structures of proteins in unwashed mixed gel promoted protein unfurling, provided more hydrophobic interactions, enhanced protein aggregation and improved the gel performance. The findings of the present study improve our understanding of the interactions between proteins from different sources. We propose a new method for modifying surimi's gel properties, facilitating the development of mixed surimi products, as well as enhancing the efficient utilization of aquatic resources. © 2024 Society of Chemical Industry.

Thermal decomposition kinetics and aging lifetime prediction of waste rubbers in porous elastic road surface

The waste rubbers used as partly aggregates in porous elastic road surface (PERS) mixture are more easily to be attacked by the heat and oxygen during the service process. This study aims to investigate the thermal decomposition kinetics of waste rubbers in PERS and propose a method to predict the lifetime of waste rubbers. Firstly, the PERS mixtures containing unaged and aged waste rubbers were prepared with void ratio of 25 % and rubber particle content of 25 %. Then, from the water residual results, it can be seen that the residual stability and freezing-thawing splitting strength ratio of PERS mixtures containing waste rubbers being aged for 7 days significantly decreased to 65 % and 59 % compared with that of the unaged PERS mixture, which cannot be used as pavement. The thermal decomposition kinetics of waste rubbers fixed with the first-order reaction, which was related with the road performance of PERS mixtures by the mass loss rate of 17 % after being aged for 7 days. Based on that, the lifetime prediction equation of waste rubbers was established. It is expected that this work provides a new strategy for predicting the lifetime of waster rubbers in PERS pavement during the service process.

Differentiation of Δ9-THC and CBD Using Silver-Ligand Ion Complexation and Electrospray Ionization Tandem Mass Spectrometry (ESI-MS/MS).

The 2018 Farm Bill defines marijuana as Cannabis sativa L. or any derivative thereof that contains greater than 0.3% Δ9-tetrahydrocannabinol (Δ9-THC) on a dry weight basis. The main cannabinoids present in Cannabis sativa L., Δ9-THC and cannabidiol (CBD), are structural isomers that cannot be differentiated using direct mass spectrometry with soft ionization techniques alone. Due to the classification of marijuana as a Schedule I controlled substance, the differentiation of Δ9-THC and CBD is crucial within the seized drug community. This study explores the use of Ag-ligand ion complexation and electrospray ionization tandem mass spectrometry (ESI-MS/MS) for the differentiation of Δ9-THC and CBD using six different Ag complexes. Differences between the binding affinities of Δ9-THC and CBD for [Ag(PPh3)(OTf)]2 lead to the formation of unique product ions at m/z 421/423, m/z 353/355, and m/z 231 for CBD, enabling the differentiation of CBD from Δ9-THC. When applied to the analysis of known Δ9-THC:CBD mixture ratios, the developed [Ag(PPh3)(OTf)]2 ion complexation method was able to differentiate Δ9-THC-rich and CBD-rich samples based on the average abundance of the product ions at m/z 421/423. The developed approach was then applied to methanolic extracts of 20 authentic cannabis samples with known Δ9-THC and CBD compositions, resulting in a 95% correct classification rate. Even though the developed Ag-ligand ion complexation method was only demonstrated for the qualitative differentiation of Δ9-THC-rich and CBD-rich cannabis, this study establishes a foundation for the use of Ag-ligand ion complexation that is essential for future quantitative approaches.

Thermophilic-mesophilic temperature phase anaerobic co-digestion compared with single phase co-digestion of sewage sludge and food waste

Anaerobic co-digestion is an effective method for addressing the issue of a single substrate not being able to achieve optimal conditions for anaerobic digestion. By adjusting the mixture ratio of sewage sludge and food waste to achieve the optimal carbon to nitrogen ratio, the effectiveness of thermophilic–mesophilic temperature phase anaerobic co-digestion (TPAcD) was evaluated in comparison to single phase mesophilic anaerobic co-digestion (MAcD) and thermophilic anaerobic co-digestion (TAcD). The results indicated that TPAcD increased methane yield by 50.3% and 32.7% compared to MAcD and TAcD, respectively. The variation in VFA, pH, and ammonia nitrogen levels demonstrated that TPAcD combines the advantages of both MAcD and TAcD, with a higher hydrolysis rate in the early stage under thermophilic conditions (55 °C) and a suitable environment in the later stage under mesophilic conditions (35 °C). The kinetic parameters of anaerobic co-digestions also demonstrated that TPAcD performs better. Therefore, further research on TPAcD of sewage sludge and food waste is warranted due to its significant improvements in methane production rate, total methane yield, and system stability. Additionally, TPAcD contributes to reducing carbon emissions and supports the realization of “carbon neutrality”.

The use of polyurethane foam-sand mixtures in sandy embankment design- predicting seismic response using FEM, catastrophe theory, B-spline method, and artificial neural networks

High-permeability sand cannot control the water that is stored behind an embankment. In addition, if clay cannot be provided within a reasonable distance of the embankment construction site, an alternative method must be found. The study proposes using a polyurethane foam-sand mixture to construct an impermeable embankment. The main purpose of the paper was to predict the seismic stability of the embankment. The nonlinear finite element models (FEMs) are applied along with artificial neural networks (ANNs), and this research method applied was performed to investigate the main objectives of the research. Catastrophe theory was used to predict the mechanism of differential displacement in the Y direction at selected points of the embankment model. For model smooth functions, the basis spline (B-spline) method was applied to simulate the catastrophe progression index value. Results revealed that the suitability of the polyurethane foam-sand mixture controls the acceleration, displacement, strain, and stress of the model at points selected in different parts of the embankment. Moreover, it was found that the deformation pattern of the model was related to the polyurethane foam-sand mixture ratios. Furthermore, the main contribution was that the seismic response of the embankment model could be improved with the right percentage of polyurethane foam added to the sand. Results were validated by referencing those available in the literature.

Optimisation of thermal regime and consolidation properties of high-silica magnesium-containing pellets

An in-depth study on the preparation process of high-silica magnetite magnesium pellets based on a grate-rotary kiln process is of great significance for promoting the utilisation of low-grade magnetite resources. When the magnetic hematite ratio is 30% and the proportion of magnesia is 1.5%, the performance of green pellets is the best. The preparation of high-silica magnesium pellets requires two stages of grate preheating for additional heating, and the appropriate preheating system is 1150°C for 15 min. The suitable magnetic hematite mixture ratio of pellets should not exceed 30%, and the reasonable magnesia ratio should not exceed 1.5%. Otherwise, the preheating temperature should be further increased, or the preheating time should be extended. The suitable roasting temperature is low, only 1225°C for 15 min, and the pellet strength can reach more than 2365N. Magnetic hematite and added magnesium flux inhibited the continuous crystallisation consolidation property in the pellet. The high SiO2 content in the gangue of high-silica magnetite impedes the recrystallisation consolidation of Fe2O3 particles in the pellet. At the same time, the primary Fe2O3 in the magnetic hematite mixed ore is less reactive than the new Fe2O3 in the magnetite oxidation. With the roasting process, the magnesium ferrite content in the pellet increases, and the recrystallisation consolidation is inhibited, so the grate-rotary kiln process to produce high-silica magnesium-containing pellets is suitable to use a higher preheating temperature to meet the requirements of grate-rotary kiln pellet strength.

Characterization of Polyphenol Composition and Starch and Protein Structure in Brown Rice Flour, Black Rice Flour and Their Mixtures.

The study investigates the structural and chemical properties of brown rice flour (WRF), black rice flour (BRF) and their mixtures in ratios of 25%, 50% and 75% to provide reference information for the gluten-free bakery industry. BRF contains higher concentrations of proteins, lipids, total minerals, crude fiber, total polyphenols, proanthocyanidins and flavonoids than WRF. A higher amylose content in BRF than in WRF resulted in flour mixtures with slower starch digestion and a lower glycemic response depending on the BRF ratio added. Differences in the chemical composition of WRF and BRF led to improved composition of the flour mixtures depending on the BRF ratio. The presence of anthocyanidins and phenolic acids in higher concentrations in the BRF resulted in a red-blue color shift within the flour mixtures. The deconvoluted FTIR spectra showed a higher proportion of α-helixes in the amide I band of BRF proteins, indicating their tighter folding. An analysis of the FTIR spectra revealed a more compact starch structure in BRF than in WRF. By processing reflection spectra, nine optically active compound groups were distinguished in rice flour, the proportion in BRF being 83.02% higher than in WRF. Due to co-pigmentation, the bathochromic shift to higher wavelengths was expressed by the proanthocyanins and phenolic acids associated with the wavelengths 380 nm to 590 nm and at 695 nm. Anthocyanins, protein-tannin complexes, methylated anthocyanins and acylated anthocyanins, associated with wavelengths 619, 644 and 668 nm, exhibited a hypsochromic effect by shifting the wavelengths to lower values. This research represents a first step in the development of rice-based products with increased nutritional value and a lower glycemic index.