Sorghum Protein Research Articles

Grain protein and amino acid dynamics in sorghum with in‐season split‐nitrogen application

AbstractBackground and ObjectivesField experiments were conducted to assess the influence of in‐season split application of nitrogen (N) on grain protein, protein digestibility, and amino acid dynamics in grain sorghum, in three different environments. Treatments included a zero N check and eight treatments with varying N application timings and amounts.FindingsThe five high N treatments had significantly greater grain protein content than all the lower N treatments. As the total protein increased, the kafirin portion of the protein increased, whereas the albumin‐globulin levels decreased. Nitrogen treatment had a significant effect on 13 of the 18 amino acids. High N applications significantly increased amino acids on a protein basis including alanine, glutamic acid, leucine, proline, and phenylalanine.ConclusionsTreatment N92 with N applied at 92 kg N ha−1 as split application at three different growth stages including planting, panicle initiation, and booting emerged as the optimum N treatment for increasing protein and amino acid concentration in grain sorghum.Significance and NoveltyThe ideal N application approach identified can be used to screen a wide range of sorghum hybrids under varying levels of irrigation and the same N treatments can be adopted by producers to enhance grain protein in sorghum.

Sorghum protein ingredients: Production, compositional variability and enhancement of aqueous dispersibility through homogenization

Sorghum protein ingredients show promising applications, given that sorghum is a resilient grain with high protein content and bioactive components, such as tannins, in certain genotypes. This study aimed to investigate the production and characterization of sorghum protein ingredients extracted from both tannin-free and tannin-rich cultivars, along with an examination of their behavior in aqueous suspensions. The use of high-pressure homogenization to improve ingredient dispersibility was also assessed. Protein extracts exhibited protein contents ranging from 50 to 67 g/100 g (wet basis), with the highest values obtained in tannin-free samples. Total lipid contents were between 18 and 26 g/100 g (wet basis), with a high contribution of free fatty acids (68–76 g/100 g lipids), and tocopherol contents ranged from 1080 to 2039 µg/g total lipids. This is substantially higher than the lipid content in flours, implying an accumulation of lipids during the protein extraction process. While the dispersibility of the protein extracts in aqueous media was initially limited, high-pressure homogenization proved effective in reducing the average size of the particles in suspension, from 9–66 µm to 1.8–2.5 µm. This processing step significantly enhanced protein dispersibility by up to 288 %, especially for the tannin-rich samples.

Sorghum proteins: Effect of extraction pH on physicochemical properties and emulsion formation

Extraction methods suitable for food applications should be studied to obtain new plant protein isolates. This study aimed to evaluate the effect of pH (8.0, 10.0, and 12.0) and temperature (20 and 40 °C) during alkaline extraction on the yield and functional and physicochemical characteristics of sorghum protein isolates and to test their ability to stabilize emulsions. The best extraction yield (58.52 %) was at pH 12.0 and 40 °C. The obtained isolates had protein concentration superior to 4-fold as compared to the raw material. Electrophoresis showed mainly prolamins, with some globulin, glutelin, and higher molecular weight polypeptides (>250 kDa). Sorghum protein isolate obtained at pH 12.0 had improved solubility (64.77 %) compared to the isolates obtained at pH 8.0 (14.50 %) and pH 10.0 (17.68 %). Emulsions with 70 % (w/w) of oil showed no phase separation during storage, and those produced with the isolate obtained at pH 12.0 were more stable, with smaller droplet sizes after the 7-day storage (25.17–44.77 μm), lower creaming index, higher emulsion stability index (ESI), and less flocculation. The study demonstrated the functional ability of sorghum protein isolates obtained by alkaline extraction to form concentrated oil-in-water emulsions, avoiding using organic solvents.

Effect of a novel drying method based on supercritical carbon dioxide on the physicochemical properties of sorghum proteins.

The aim of this research was to use supercritical carbon dioxide (SC-CO2) drying as a novel approach for generating sorghum protein concentrates/isolates with enhanced functional properties. Sorghum protein extracts were obtained from white whole-grain sorghum flour and were dried by two methods, namely, freeze-drying and SC-CO2 drying. The collected proteins were characterized for their morphology, color, crystallinity, surface hydrophobicity, emulsifying activity index (EAI), creaming index (CI), foaming capacity (FC), foaming stability (FS), protein solubility, chemical interactions, and viscosity. The SC-CO2-dried proteins exhibited higher porosity compared to the freeze-dried ones with smaller particle sizes (∼5.1 vs. 0.4 μm, respectively). The XRD patterns indicated that the SC-CO2-dried proteins had a lower crystallinity than the freeze-dried proteins. However, the surface hydrophobicities of the freeze-dried and SC-CO2-dried proteins were similar. The EAI results showed that the emulsifying activity of freeze-dried protein powder (40.6) was better than that of SC-CO2-dried protein powder (29.8). Nevertheless, the solubility of SC-CO2-dried proteins was higher than that of freeze-dried proteins in most of the pHs investigated. Overall, the proposed SC-CO2 drying method has the potential to generate porous protein powders with improved solubility that can be used in developing functional foods.

Investigating sorghum protein solubility and in vitro digestibility during seed germination

In this work, we examined the impact of sorghum gain germination on kafirins solubility and digestibility. Two genotypes differing in their proteins and tannins contents were germinated under controlled conditions up to radicle emergence. Biochemical, physicochemical, and in vitro digestibility tests were applied on the germinated grains. Microscopic examination of grains endosperm revealed that germination resulted in pitted starch granules and protein matrix slackening. Apart cystine and the amount of free thiol groups which increased significantly, the overall amino acids composition remained rather unchanged, just as the kafirins solubility and size distribution. In contrast germination was demonstrated to improved significantly the in vitro protein digestibility, even after cooking and especially for the genotype poor in tannin. Without inducing major physicochemical changes, germination enhanced kafirins susceptibility to gastrointestinal proteases. Germination may be a way to improve the nutritional value of sorghum.

The Rapid Non-Destructive Detection of the Protein and Fat Contents of Sorghum Based on Hyperspectral Imaging

The Rapid Non-Destructive Detection of the Protein and Fat Contents of Sorghum Based on Hyperspectral Imaging

Optimitimization of sorghum protein isolates as a by-product of starch extraction using enzymatic methods

The lack of protein consumption in Indonesian society has caused an increase in malnutrition sufferers in the country. One of the prevention efforts is making protein isolates with sorghum as raw materials because sorghum is a cereal with the highest protein content compared to other grains. To produce food-grade isolates, the isolation process is carried out with the help of the α-amylase enzyme, which has an activity of 6,666,563 units/ml. This study aimed to determine the optimization value and functional characteristics of sorghum protein isolate produced using enzymatic methods. This research was conducted with an experimental method followed by hypothesis testing using a CCD (Central Composite Design) RSM (Response Surface Methodology) test with α-amylase enzyme variables and 0.9 % -1.8% and 1.5-2.5 hours for reaction times of each upper and lower limit. The desired response variable is protein content. Protein isolates with the highest levels or 58.40% were obtained with an enzyme amount of 1.35% with a hydrolysis length of time of 3.4 hours. Estimation validation will get optimum levels or more than 90% will be produced using the α-amylase enzyme of 2.63% and hydrolyzed for 2 hours.

Amino acid profiling and structural characterization of sorghum protein concentrates using enzyme liquefaction

Amino acid profiling and structural characterization of sorghum protein concentrates using enzyme liquefaction

Nutritional value and agronomic traits of forage sorghum under drought stress

Drought negatively affects the crop yield and nutritional value of forage sorghum. The effect of drought on forage sorghum was investigated in a two-year, strip plot field experiment with a randomized complete block design. The vertical factor included four levels of drought stress (mild, moderate, severe, and extreme), and the horizontal factor consisted of four forage sorghum genotypes (Spidfid, Sugargraze, Jumbo, and Pegah). The results showed that drought stress negatively influenced plant height, number of leaves, biomass, leaf-to-stem ratio, and seed yield and yield components, as well as crude protein and prussic acid contents of sorghum. However, the different genotypes did not show the same responses to drought stress. The highest forage yield was observed in Spidfid genotype under mild stress by 121.6 ton/ha, the lowest related value (30.5) was obtained in Sugargraze genotype under extreme drought. The highest seed yields were recorded in the Spidfid genotype in mild and extreme stress treatments (7861 and 4839 kg/ha, respectively). The Sugargraze genotype showed the highest yield reduction under extreme stress. The nutritional value of forage was significantly higher in the Spidfid genotype, and the same genotype contained the lowest prussic acid content under mild and extreme stress conditions by 87 and 86 mg/kg, respectively. However, the crude protein content of the genotypes was not significantly different under severe stress. Therefore, using the Spidfid tolerant genotype and reducing the irrigation period in water shortage conditions, can be a promising solution to achieve the ideal quantitative and qualitative yield of sorghum forage.

Compositional analysis in sorghum (Sorghum bicolor) NIR spectral techniques based on mean spectra from single seeds.

Sorghum (Sorghum bicolor) is an economically important cereal crop that can be used as human food, animal feed, and for industrial use such as bioenergy. In sorghum breeding programs, development of cultivars with desirable seed quality characteristics is important and development of rapid low-cost screening methods for seed nutritional traits are desired, since most standard methods are destructive, slow, and less environmentally friendly. This study investigates the feasibility of single kernel NIR spectroscopy (SKNIRS) for rapid determination of individual sorghum seed components. We developed successful multivariate prediction models based on partial least squares (PLS) regression for protein, oil, and weight in sorghum. The results showed that for sorghum protein content ranging from 8.92% to 18.7%, the model coefficients of determination obtained were (RMSEC= 0.44) and (RMSEP= 0.69). The model coefficients of determination for oil prediction were (RMSEC= 0.23) and (RMSEP= 0.41) for oil content ranging from 1.96% to 5.61%. For weight model coefficients of determination were (RMSEC= 0.007) and (RMSEP= 0.007) for seeds ranging from 4.40 mg to 77.0 mg. In conclusion, mean spectra SKNIRS can be used to rapidly determine protein, oil, and weight in intact single seeds of sorghum seeds and can provide a nondestructive and quick method for screening sorghum samples for these traits for sorghum breeding and industry use.

Formation of cereal protein disulfide-linked stable matrices by apigeninidin, a 3-deoxyanthocyanidin

The food matrix is a factor affecting digestion rate of macronutrients, like starch. Sorghum protein networks surrounding starch have been associated with its comparatively low starch digestibility, though their formation mechanism is unclear. Since sorghums contain 3-deoxyanthocyanidins with redox property that could promote sulfhydryl-disulfide interchanges, we hypothesized that added apigeninidin (a 3-deoxyanthocyanidin) will form matrices in a non-matrix-forming cereal (corn). A model system using ovalbumin determined apigeninidin as a polymerizing agent. Starch digestion and microstructure of cereal porridges from yellow corn with and without added apigeninidin, commercial blue corn, and white sorghum were examined. Apigeninidin addition promoted protein matrices in yellow corn and attenuated initial starch digestion rate that was related to matrix formation rather than α-amylase inhibition. Blue corn with 3-deoxyanthocyanidins formed protein matrices with similar lower overall starch digestibility as sorghum. Promoting matrix formation in cereal-based foods with 3-deoxyanthocyanidins may be a strategy to modulate starch digestion rate.

Corn (Zea mays L.) and sorghum (Sorghum bicolor (L.) Moench) yield and nutritional quality affected by drought stress

Comparison of drought tolerance of crop plants is important for planning efficient cropping strategies and increasing yield production. The objective was to investigate the effects of drought stress including control (S1), 80 (moderate, S2) and 60% (severe, S3) of crop essential irrigation (determined by evaporation from the Class A evaporation pan) on grain yield and nutritional quality of different corn (Zea mays L.) (Maxima (sensitive) and 704 (tolerant)) and sorghum (Sorghum bicolor (L.) Moench) (Kimia (sensitive) and Payam (tolerant)) genotypes. The experiment, conducted in 2019, was a split plot based on randomized complete block design with three replicates. Plants yields and nutritional quality including relative water content (RW), fiber, protein, starch, tannin, and chlorophyll were measured. Although water stress did not significantly affect RW in corn, it significantly affected RW in sorghum. Fiber concentration was the highest at the severe stress in both corn genotypes (9.36% in 704 and 10.35% in Maxima), and sorghum Payam genotype (14.54%). The lowest (13.29%) and the highest (14.35%) corn protein content were obtained for Maxima in the medium and control level of stress, and for 704 genotype it ranged from 13.51 to 13.77%. Sorghum protein was the highest in the sensitive and tolerant genotypes in control and severe stress, respectively. Treatments S3 and S2 resulted in the highest (14.58%) and the lowest (12.47%) protein content for sorghum Kimia genotype. Although sorghum plants were tolerant in stress conditions, corn plants could also tolerate the stress up to some level by adjusting their physiological characteristics.

Stable sorghum grain quality QTL were identified using SC35 × RTx430 mapping population.

Understanding the genetic control and inheritance of grain quality traits is instrumental in facilitating end-use quality improvement. This study was conducted to identify and map quantitative trait loci (QTL) controlling protein, starch, and amylose content in grain sorghum [Sorghum bicolor (L.) Moench] grown under variable environmental conditions. A recombinant inbred line (RIL) population derived from a cross between RTx430 and SC35 was evaluated in six environments across Hays and Manhattan, KS. Significant variation was observed in genotype, environment, and genotype × environment interaction for all three quality traits. Unlike the RILs, the two parental lines did not show significant differences for these traits. However, significant transgressive segregation was observed for all traits resulting in phenotypic performance extending beyond the two parents. A total of seven protein, 10 starch, and 10 amylose content QTL were identified. Chromosomal regions and phenotypic variation (PVE) of QTL were variable across growing conditions. Quantitative trait loci hotspots for all three traits were detected on chromosomes 1 (115.2-119.2 cM) and 2 (118.2-127.4 cM). Candidate gene analysis indicated that these QTL hotspots were conditioned by several transcription factors, such as Cytochrome P450 and basic helix-loop-helix DNA binding protein, which regulate starch and protein accumulation in the grain. The identified genomic regions and underlying candidate genes provide a starting point for further validation and marker-assisted gene pyramiding to improve sorghum grain quality.

Precooked sorghum flour as proper vehicle of ACE‐I and DPP‐IV inhibitory sorghum peptides

AbstractSorghum flour was heat treated for producing an instant dispersion ingredient. The precooked sorghum flour was added with ACE‐I and DPP‐IV inhibitory sorghum peptides (3.0 g peptide 100 g−1). The product was reconstituted in water, and peptide bioaccessibility was evaluated by equilibrium dialysis method after simulated gastrointestinal digestion. Total peptide dialysability of precooked sorghum flour added with sorghum peptides was higher than those obtained for precooked sorghum flour (315.9 ± 14.8 vs. 45.2 ± 5.6 µmol, respectively) (P < 0.05). The ACE‐I and DPP‐IV‐IC50 values of the bioaccessible peptides from the bioactive product were lower than those obtained for precooked sorghum flour ingredient (1.04 ± 0.12 vs. 1.82 ± 0.09 and 0.86 ± 0.02 vs. 2.12 ± 0.08 mg protein mL−1, for ACE‐I and DPP‐IV, respectively) indicating a higher activity. Precooked sorghum flour was a good vehicle since it did not affect the bioaccessibility of ACE‐I and DPP‐IV inhibitory peptides provided by sorghum protein hydrolysate.

Prediction of tannin, protein, and total phenolic content of grain sorghum using image analysis and machine learning

AbstractBackground and ObjectivesSorghum is an alternative crop where poor soil is a limiting factor for the production of corn. Laboratory measurements of chemical compounds of grains are expensive, time‐consuming predominantly done on powdered samples. Therefore, a rapid and reliable method integrating image processing and machine learning was evaluated for the prediction of total phenolic compounds (TPCs), tannin, and protein.FindingsThe highest TPC (0.83%) was obtained for genotype KGS36 (the brown pericarp) followed by KGS23 (0.54%). The concentration of tannin ranged from 0.008% to 0.616%. Mean comparison revealed variation for the protein concentration (15.17%–11.53%); the highest content obtained by KGS25 and the lowest by KGS36 (p < .01). Multilayer perceptron (MLP) as one of the common artificial neural networks (ANNs) applied to simulate the chemical of the grains was evaluated through the textural features extracted from grain images. For the MLP network, the minimum number of hidden networks was set to 8 and the maximum number was set to 25. For learning and saving, the number of networks was set to 20 and the number of saved networks was set to 5. The best MLP models were selected based on performance (R) and error values for the train, test, and validation sets.ConclusionsAn ANN for the prediction of the chemical concentration was suggested. The correlations between predicted and observed data were higher than .915.Significance and NoveltyThese models are of great significance for the prediction of chemical concentrations of grain sorghum in plant breeding and food industry.

Sorghum Protein Extract Protects RBC from Sodium Nitrite-Induced Oxidative Stress and Exhibits Anticoagulant and Antiplatelet Activity

Oxidative stress plays a critical role in the progression of diabetes, arthritis, cancer, eryptosis, cardiovascular disease, and thrombosis. Currently, antioxidants from natural sources are in high demand due to their beneficial role in the management of said diseases. The purpose of the study was to evaluate the protective effect of sorghum protein buffer extract (SBE) on sodium nitrite-induced oxidative stress and thrombosis. Protein characterization of SBE was done using SDS-PAGE. Oxidative stress in RBC was induced using sodium nitrite (NaNO2) and the key stress markers such as lipid peroxidation (LPO), protein carbonyl content (PCC), and the level of antioxidant enzymes (SOD and CAT) were measured. The anticoagulant effect of SBE was identified by employing in-vitro plasma recalcification time, activated partial thromboplastin time (APTT), prothrombin time (PT), and in-vivo mouse tail bleeding time. SBE antiplatelet activity was examined using agonist adenosine diphosphate (ADP) and epinephrine-induced platelet aggregation. Non-toxic property of SBE was identified using in-vitro direct haemolytic, haemorrhagic, and edema forming activities using experimental mice. SBE revealed similar protein banding pattern under both reduced and non-reduced conditions on SDS-PAGE. Interestingly, SBE normalized the level of LPO, PCC, SOD, and CAT in stress-inducedRBCs. Furthermore, SBE showed anticoagulant effect in platelet rich plasma by enhancing the clotting time from the control 250 s to 610 s and bleeding time from the control 200 s to more than 500 s (p<0.01) in a dose dependent manner. In addition, SBE prolonged the clot formation process of only APTT but not PT. SBE inhibited the agonists ADP and epinephrine induced platelet aggregation. SBE did not hydrolyze RBC cells, devoid of edema and haemorrhage properties. This study demonstrates for the first time the anticoagulant, antiplatelet, and antioxidant properties of SBE. Thus, the observed results validate consumption of sorghum as good for health and well-being.

Antioxidant activity, carbohydrates and protein in sorgum (Sorghum bicolor L. Moench) plants as a development of economic functional food materials during the COVID-19 pandemic

This study aims to determine the content of antioxidants, carbohydrates, and protein in Sorghum (Sorghum bicolor L. Moench) as an economically functional food ingredient during the COVID-19 pandemic. The research stages include the manufacture of sorghum seed extract, Antioxidant level testing using the DPPH test, carbohydrate content testing, and protein content determination using the Kjeldahl method, the Kjeldahl method consists of 3 stages, namely: the destruction stage, the distillation stage, and the titration stage. The results showed that Sorghum had an IC50 value of 88.8970 ppm, carbohydrate content of 71.8 g, and protein content of 9.68%. so that sorghum has the potential to develop functional food during the COVID-19 pandemic.

Interaction mechanism of kafirin with ferulic acid and tetramethyl pyrazine: Multiple spectroscopic and molecular modeling studies

Ferulic acid (FA) and tetramethyl pyrazine (TMP) are intrinsic bioactive compounds in baijiu, and kafirin is the major protein of sorghum, which is the raw material of baijiu. In this study, the interactions of kafirin-FA and kafirin-TMP were investigated by multiple spectroscopic and molecular modeling techniques. Fluorescence spectra showed that intrinsic fluorescence of kafirin drastically quenched because of the formations of kafirin-FA and kafirin-TMP complexes. The CD studies indicated that the combination with FA or TMP decreased the α-helix content of kafirin slightly. The shifts and intensity changes of UV–Vis, FTIR and fluorescence spectra confirmed the formations of complexes. Moreover, the molecular docking and molecular dynamics studies showed that hydrophobic interactions and hydrogen bonds played major roles in the formations of kafirin-FA and kafirin-TMP complexes, and the formations of complexes made kafirin structures more compact. This work is of great importance for further quality improvement in baijiu and alcoholic beverages.

Identification of a bacterial-type ATP-binding cassette transporter implicated in aluminum tolerance in sweet sorghum (Sorghum bicolor L.)

ABSTRACT Aluminum (Al) toxicity in acidic soils severely reduces crop production worldwide. Sorghum (Sorghum bicolor L.) is an important agricultural crop widely grown in tropical and subtropical regions, where Al toxicity is prevalent. ATP-binding cassette (ABC) transporters play key roles in the development of plants and include the member sensitive to aluminum rhizotoxicity 1 (STAR1), which is reported to be associated with Al tolerance in a few plant species. However, a STAR1 homolog has not been characterized in sorghum with respect to Al tolerance. Here, we identified and characterized a SbSTAR1 gene in sweet sorghum encoding the nucleotide-binding domain of a bacterial-type ABC transporter. The transcriptional expression of SbSTAR1 is induced by Al in a time- and dosage-dependent manner in root, especially in root tip, which is the key site of Al toxicity in plants. The typical Al-associated transcription factor SbSTOP1 showed transcriptional regulation of SbSTAR1. SbSTAR1 was present at both the cytoplasm and nuclei. Overexpression of SbSTAR1 significantly enhanced the Al tolerance of transgenic plants, which possibly via regulating the hemicellulose content in root cell wall. This study provides the first ABC protein in sorghum implicated in Al tolerance, suggesting the existence of a SbSTAR1-mediated Al tolerance mechanism in sorghum.

Fabrication of pristine electrospun kafirin nanofiber mats loaded with thymol and carvacrol

In this project, we fabricated electrospun nanofiber mats from pristine kafirin, the storage protein of sorghum, for the first time which have the potential to be used as eco-friendly food packaging materials. The first novel step was kafirin extraction which showed that the purity of kafirin was higher in double-purification compared to single-purification, which led to high quality nanosized round, straight, unbroken and unentangled fibers. The electrospinning results indicate that binary solvent, 75% (v/v) acetic acid (AcOH) and 25% (v/v) butanol (BuOH) mixture, allows fabrication of homogenous nanofiber mats at 0.4 g/ml kafirin-to-solvent ratio, which is critical for to obtain good mechanical strength for the mats. Encapsulation of thymol and carvacrol was successful when the loading concentrations were 0.1 g/ml and 0.1–0.2 g/ml, for thymol and carvacrol, respectively. Loading of the fibers with the bioactives was confirmed with FTIR where the characteristic peaks for the bioactives appeared at 950 cm−1, 1150 cm−1, 1200 cm−1 and 1250 cm−1. Thymol or carvacrol encapsulation led to the conversion of some of the β-turn structures of kafirin into β-sheet structures. Surface hydrophilicity of loaded kafirin fiber mats decreased with increasing carvacrol concentration and increased with increasing thymol concentration.