Sweet Corn Kernels Research Articles

Performance of a mixed-mode air recirculation solar dryer integrated with thermal energy storage and evacuated tube solar collector for drying sweet corn kernels

Performance of a mixed-mode air recirculation solar dryer integrated with thermal energy storage and evacuated tube solar collector for drying sweet corn kernels

Unlocking the genetic basis of vitamin E content in sweet corn kernels: Expanding breeding targets through genome-wide association studies

Tocochromanols, collectively known as Vitamin E, serve as natural lipid-soluble antioxidants that are exclusively obtained through dietary intake in humans. Synthesized by all plants, tocochromanols play an important role in protecting polyunsaturated fatty acids in plant seeds from lipid peroxidation. While the genes involved in tocochromanol biosynthesis have been fully elucidated in Arabidopsis thaliana, Oryza sativa and Zea mays, the genetic basis of tocochromanol accumulation in sweet corn remains poorly understood. This gap is a consequence of limited natural genetic diversity and harvest at immature growth stages. In this study, we conducted comprehensive genome-wide association studies (GWAS) on a sweet corn panel of 295 individuals with a high-density molecular marker set. In total, thirteen quantitative trait loci (QTLs) for individual and derived tocochromanol traits were identified. Our analysis identified novel roles for three genes, ZmCS2, Zmshki1 and ZmB4FMV1, in the regulation of α-tocopherol accumulation in sweet corn kernels. We genetically validated the role of Zmshki1 through the generation of a knock-out line using CRISPR-Cas9 technology. Further gene-based GWAS revealed the function of the canonical tyrosine metabolic enzymes ZmCS2 and Zmhppd1 in the regulation of total tocochromanol content. This comprehensive assessment of the genetic basis for variation in vitamin E content establishes a solid foundation for enhancing vitamin E content not only in sweet corn, but also in other cereal crops.

The interaction of glycogen nanoparticles with human blood.

Glycogen, a naturally sourced highly branched polysaccharide nanoparticle, has been receiving attention in the field of nanomedicine due to its inherent non-toxicity and biodegradability. However, often in the literature glycogen nanoparticles (NPs) are used that come from different commercial sources (animals and tissues), which have significantly different sizes, molecular weights, and protein content, meaning a comprehensive overview of the interactions of these differently-sourced NPs with the human immune system is missing. Herein, we investigated coagulation, immune cell association and inflammation responses triggered by source-dependent interactions of glycogen NPs in human blood, utilising four types of commercially available glycogen: phytoglycogen (PG) isolated from sweet corn kernels, oyster glycogen (OG), rabbit liver glycogen (RLG), and bovine liver glycogen (BLG). Our results reveal that glycogen NPs exhibit minimal immune cell association, low complement factor, granulocyte, and platelet activation, and have no impact on blood clotting. This is despite the significant physico-chemical differences between the NP types, and when studied at exceptionally high particle concentrations (orders of magnitude higher than other typically studied synthetic systems). Given the similarities in the interactions with blood, either of the commercial glycogens can be leveraged in nanomedicine with respect to immuno-interactions, though PG provides a sustainable and ethically sourced form of NPs from plants. Together, our results highlight a key benefit of using glycogen NPs as injectable biomaterials for therapeutic applications.

Preharvest 24-epibrassinolide treatment prolongs harvest duration and shelf life in sweet corn

Sweet corn is perishable and have limited harvest duration and shelf life due to their quality deterioration. Reactive oxygen species (ROS) are one of the most predominant factors for maintaining quality of sweet corn during and after harvest. Brassinosteroids (BRs) can enhance the activity of antioxidant enzymes and decrease the ROS level in plants. In this study, we found that a bioactive BR (24-epibrassinolide, EBR) treatment before harvest markedly inhibited change of quality indicators (MDA content, weight loss rate, and soluble sugar content) during and after harvest. Further analysis revealed that EBR promoted the activity and transcriptions of antioxidant enzymes, maintaining lower ROS level in kernels. Meanwhile, exogenous EBR increased the expression level of genes controlling sucrose transport in sweet corn kernels. Bioinformatics and binding analysis identified that BR transcription factor ZmBES1/ZmBZR1-10 might potentially bind to and upregulate transcriptions of antioxidant enzyme genes including SOD and POD genes, and sucrose transport-related genes including SUT and SWEET genes. These results indicated that exogenous application of EBR ameliorates quality during and after harvest by improving the antioxidant capacity and photosynthetic assimilates accumulation rate of sweet corn, thus prolonging harvest duration and shelf life in sweet corn.

Impact of low temperature on the chemical profile of sweet corn kernels during post-harvest storage

Fresh sweet corn has a limited shelf-life due to its high moisture and high sugar content. Low temperature storage is an effective technique employed to extend the shelf-life. However, changes in the chemical composition of sweet corn kernels at low temperatures are not fully understood. In this study, kernels stored at low temperature exhibited higher levels of soluble sugars and lower starch content. In total, 1365 metabolites were characterized in sweet corn kernels. 593 and 308 differentially accumulated metabolites (DAMs) were identified in sweet corn kernels stored at normal and low temperature, respectively. 607 DAMs were identified at low temperature compare to normal temperature. DAMs were consistently enriched in flavonoid biosynthesis, linoleic acid metabolism and sphingolipid metabolism. Moreover, dozens of metabolites were identified as potential biomarkers for post-harvest storage effects in sweet corn. These results extend our knowledge of the dynamic changes in sweet corn kernels stored at low temperatures.

Rehydration modeling and characterization of dehydrated sweet corn.

The increasing demand of rehydrated foods is due to its better storage stability at ambient conditions and not requiring refrigeration. Prior to drying at 55, 60, 65, and 70°C in a hot air tray dryer, hot water blanching (HB), steam blanching (SB), and microwave blanching (MB) were employed as pretreatments. Rehydration of dried pretreated sweet corn kernel was performed in boiling water. The pretreatments and drying temperatures were independent factors that affected the dependent factors such as rehydration ratio, total sugar, ascorbic acid, geometric mean diameter, color, sensory evaluation, water absorption, mass, and geometric mean diameter. Peleg, Weibull, and newly proposed models were considered to describe the change in moisture content during rehydration. The proposed model performed better than other models and indicated the rise in equilibrium moisture content of rehydrated sweet corn with an increase in dehydration temperature of sweet corn due to higher R 2 (0.994), and lower chi-square (0.005) and RMSE (0.064). The rehydrated sweet corn obtained from samples processed with microwave blanching and dehydration at 70°C showed higher retention of total sugar, ascorbic acid, geometric mean diameter, and color.

Influence of Integrated use of Organic and Inorganic sources of nutrients on quality parameters of Sweet Corn

A field experiment entitled “Sustaining soil health and productivity of sweet corn through nutrient management” was conducted at Agricultural College Farm, Bapatla using sweet corn hybrid maize Mahy-301 as a test crop. The experiment comprising of 10 treatments was laid out in completely randomized block design and were replicated thrice. The biochemical composition of sweet corn kernel was significantly influenced by the different nutrient management practices. The maximum protein content (10.56%) was observed in T2 (100 per cent RDF) whereas the highest starch content (54.33 %) and sucrose content (8.57 %) was observed in treatment which received 50 per cent RDF with FYM @ 5 t ha-1

Physicochemical, color, and sensory characteristics of edible oil‐coated blanched sweet corn kernels

AbstractSweet corn has a higher moisture content, making it challenging to store for longer. The edible coating acts as primary packaging. The samples were blanched in hot water at 90°C for 90 s initially and were coated with olive oil concentration 0%–100% for 60–300 s at temperatures of 40–60°C, which makes the kernels acceptable even after 7 days in comparison to 4 days in untreated samples. The coating of hot water‐blanched sweet corn kernels increased length, width, thickness, true density, porosity, color a*, color b*, ∆E, chroma, browning index, moisture content, and pH with increased coating time, coating temperature, and concentration and varied from 11.78 to 12.40 mm, 9.87 to 10.22 mm, 4.14 to 4.66 mm, 1082 to 1093 kg/m3, 33.70% to 37.29%, 4.19 to 4.57, 0.09 to 1.36, 7.46 to 8.34, 14.11 and 12.43, 78.32% to 83.41% and 5.87 to 5.98. While the coating process decreased bulk density, color L*, total sugar, ascorbic acid, and total soluble solid of sweet corn kernels with an increase in coating time and coating temperature and varied from 685.43 to 717.32 kg/m3, 74.68 to 75.12, 6.4% to 7.2%, 6.4 to 7.1 mg/100 g and 18.5 to 19.8 °Brix, respectively. The coating of sweet corn and hot water blanching is a promising hurdle to spoilage for extending the shelf life of sweet corn in food processing industries for developing various processed food products.

Binding Affinity of Concanavalin A to Native and Acid-Hydrolyzed Phytoglycogen Nanoparticles.

Phytoglycogen (PG) is a polysaccharide produced in the kernels of sweet corn as soft, highly branched, compact nanoparticles. Its tree-like or dendritic architecture, combined with a high-safety profile, makes PG nanoparticles attractive for use in biological applications, many of which rely on the association or binding of small biomolecules. We have developed a methodology to functionalize surface plasmon resonance (SPR) sensor surfaces with PG nanoparticles, and we demonstrate the utility of the PG-functionalized SPR sensor by measuring the binding affinity of the tetrameric concanavalin A (ConA) protein to both native PG nanoparticles and smaller, softer acid-hydrolyzed PG nanoparticles. We measure comparable values of the equilibrium association constant K for native and acid-hydrolyzed PG, with a slightly smaller value for the acid-hydrolyzed particles that we attribute to unfavorable lateral interactions between the tetrameric subunits of ConA due to the increase in surface curvature of the smaller acid-hydrolyzed PG particles. We also use infrared reflection-absorption spectroscopy (IRRAS) to show that ConA maintains a large fraction of its native conformation, and thus its bioactivity, upon binding to PG, representing an important step toward the realization of PG as a novel bioactive delivery vehicle.

A genome-wide association study of folates in sweet corn kernels.

Folate is commonly synthesized in natural plants and is an essential water-soluble vitamin of great importance inhuman health. Although the key genes involved in folate biosynthesis and transformation pathways have been identified in plants, the genetic architecture of folate in sweet corn kernels remain largely unclear. In this study, an association panel of 295 inbred lines of sweet corn was constructed. Six folate derivatives were quantified in sweet corn kernels at 20 days after pollination and a total of 95 loci were identified for eight folate traits using a genome-wide association study. A peak GWAS signal revealed that natural variation in ZmFCL, encoding a 5-formyltetrahydrofolate cyclo-ligase, accounted for 30.12% of phenotypic variation in 5-FTHF content. Further analysis revealed that two adjacent SNPs on the second exon resulting in an AA-to-GG in the gene and an Asn-to-Gly change in the protein could be the causative variant influencing 5-FTHF content. Meanwhile, 5-FTHF content was negatively correlated with ZmFCL expression levels in the population. These results extend our knowledge regarding the genetic basis of folate and provide molecular markers for the optimization of folate levels in sweet corn kernels.

Effects of radiofrequency blanching on lipoxygenase inactivation, physicochemical properties of sweet corn (Zea mays L.), and its correlation with cell morphology

This study investigated the effects of radiofrequency (RF) and boiling-water (BW) blanching on lipoxygenase (LOX) activity, physicochemical properties, and changes in the cellular morphology of sweet corn kernels. First, a speed-adjustable device was introduced to rotate the sample for improving heating uniformity. Then, the maximum RF heating rate and uniform temperature distribution of samples were obtained under 160 mm electrode gap, 120 g sample weight, and 14 r/min rotating speed. With increased RF heating temperature ranging from 50 °C to 80 °C, the residual activity of LOX significantly decreased to 4.68%. Samples blanched by RF treatment maintained better color, texture, and nutrient content than those by BW when similar levels of enzyme inactivation were achieved. Micrographs also showed the cells were increasingly damaged with increased RF heating temperature, whereas the cells were damaged much more severely when treated with BW. Besides, microscopic destruction of cells also explains the changes in physicochemical properties.

Transition in the Glassy Dynamics of Melts of Acid-Hydrolyzed Phytoglycogen Nanoparticles.

The deformability, responsiveness, and tunability of soft nanoparticles (NPs) offer unique opportunities to learn about their complex properties and the interactions between particles. In the present study, we provide new insights into the physical properties of phytoglycogen (PG) NPs, which are soft, compact particles with a dendritic architecture that are produced in the kernels of sweet corn. In particular, we study PG NPs modified using acid hydrolysis, which not only reduces their diameter but also alters their stiffness, internal structure, and the interactions between particles in aqueous dispersions. We used steady shear rheology to determine the dependence of the relative zero-shear viscosity ηr of aqueous dispersions of acid-hydrolyzed PG NPs on the effective volume fraction ϕeff, which indicated a reduction in stiffness of the particles relative to that of native PG NPs. We quantified this difference by analyzing the nature of the colloidal glasses formed at high ϕeff. We measured a smaller value of the fragility index m for acid-hydrolyzed PG NP glasses than that for native PG NP glasses, indicating that acid-hydrolyzed PG NPs form stronger glasses and are therefore softer than native PG NPs. Unlike the native PG NPs, we observed a distinctive change in the character of the glass transition of the acid-hydrolyzed PG NPs as ϕeff was increased above ϕeff∼1: a crossover in the dependence of ηr on ϕeff from Vogel-Fulcher-Tammann behavior to a more gradual, Arrhenius-like behavior. By expressing the steady shear and oscillatory rheology data in terms of generalized Péclet numbers, we obtained collapse of the data onto master curves. We interpret this result in terms of the acid-hydrolyzed PG NPs predominantly interpenetrating neighboring particles at large ϕeff, for which fluctuations of the outer chains enhance the mobility of the particles and make α-relaxation times τα experimentally accessible.

Mathematical modelling and characterization of drying of pre-treated sweet corn (Zea mays L.) kernels.

The pre-treated sweet corn samples were dried at temperatures of 55, 60, 65 and 70°C and thin layer drying characteristics of sweet corn were assessed. Mathematical models were fitted and evaluated using R2, χ2, RMSE values. The effective diffusivities for the drying process were 4.32 × 10-10 to 1.08 × 10-9m2/s and activation energies were 34.51 to 38.99kJ/mol. Total sugar and ascorbic acid of dehydrated sweet corn kernels varied from 5.50 to 13.00g/100g and 3.30 to 10.50mg/100g respectively. The sample pre-treated with microwave blanching and dried at 70°C obtained higher sensory score after rehydration, indicating suitability of the dehydrated sweet corn.

Improved agronomic biofortification of sweetcorn achieved using foliar rather than soil Zn applications

AbstractBackground and ObjectivesThis field and glasshouse study evaluates the relative effectiveness of agronomic zinc biofortification strategies to increase the Zn concentration in sweetcorn (Zea mays) kernels for human health, using applications of Zn fertilizer to the root‐zone or to foliage.FindingsPlants accumulated additional Zn as the rate of Zn applied to the root‐zone increased, but most was retained in the stems and foliage and little was translocated into the kernels (≤7%). A large proportion of the additional Zn stored in the foliage was in the form of Zn‐phytate. In contrast, in field‐grown plants where soil Zn was adequate for maximizing commercial yields, Zn applications to foliage increased kernel Zn concentrations by up to 100%. ZnSO4·7H2O was more effective to use in foliar applications compared with Zn‐EDTA.ConclusionThe elevated kernel concentrations recorded for two varieties (59.1 and 71.1 mg Zn kg−1) were greater than all previously reported biofortification responses from maize. These concentrations also matched or exceeded the HarvestPlus target of 60 mg Zn kg−1 for maize.Significance and NoveltyWith a total kernel Zn content of 3.6 mg Zn per cob, approximately 25%–45% of the recommended dietary Zn intake could be met with one cob of Zn‐biofortified sweetcorn.

Transcriptome‐wide association and prediction for carotenoids and tocochromanols in fresh sweet corn kernels

Sweet corn (Zea mays L.) is consistently one of the most highly consumed vegetables in the United States, providing a valuable opportunity to increase nutrient intake through biofortification. Significant variation for carotenoid (provitamin A, lutein, zeaxanthin) and tocochromanol (vitamin E, antioxidants) levels is present in temperate sweet corn germplasm, yet previous genome-wide association studies (GWAS) of these traits have been limited by low statistical power and mapping resolution. Here, we employed a high-quality transcriptomic dataset collected from fresh sweet corn kernels to conduct transcriptome-wide association studies (TWAS) and transcriptome prediction studies for 39 carotenoid and tocochromanol traits. In agreement with previous GWAS findings, TWAS detected significant associations for four causal genes, β-carotene hydroxylase (crtRB1), lycopene epsilon cyclase (lcyE), γ-tocopherol methyltransferase (vte4), and homogentisate geranylgeranyltransferase (hggt1) on a transcriptome-wide level. Pathway-level analysis revealed additional associations for deoxy-xylulose synthase2 (dxs2), diphosphocytidyl methyl erythritol synthase2 (dmes2), cytidine methyl kinase1 (cmk1), and geranylgeranyl hydrogenase1 (ggh1), of which, dmes2, cmk1, and ggh1 have not previously been identified through maize association studies. Evaluation of prediction models incorporating genome-wide markers and transcriptome-wide abundances revealed a trait-dependent benefit to the inclusion of both genomic and transcriptomic data over solely genomic data, but both transcriptome- and genome-wide datasets outperformed a priori candidate gene-targeted prediction models for most traits. Altogether, this study represents an important step toward understanding the role of regulatory variation in the accumulation of vitamins in fresh sweet corn kernels.

Physicochemical characteristics of sweet corn kernels during microwave blanching

Sweet corn kernels are easily perishable because of their high amount of moisture content. Microwave blanching was applied at the power level of 180–900 W for 30–70 s to inactivate the enzymes of sweet corn kernels. The increase in microwave power level and processing time reduced the length from 11.13 to 10.78 mm, width from 9.54 to 9.24 mm, thickness from 4.01 to 3.71 mm, true density from 1052.07 to 1012.03 kg/m3, porosity from 37.43 to 24.54%, moisture content from 70.00% to 68.93% on a wet basis, total soluble solid from 22.3 to 18.7 °Brix, total sugar from 8.80% to 6.67%, ascorbic acid from 8.04 to 5.92 mg/100 g, and peroxidase activity up to 1.37% in sweet corn kernels, but it increased the bulk density from 658.23 to 763.6 kg/m3 and total color difference up to 14.55. Novelty impact statement The microwave blanching was found adequate for processing sweet corn kernels at the power level of 720 W for a short duration of 40 s to achieve a 90% reduction in peroxidase activity. The ascorbic acid, total sugar, overall acceptability after the microwave blanching were 6.86 mg/100 g, 7.87%, and 8.21, respectively, indicating 85, 89, and 94% retention of fresh samples properties. The total plate count was 9.1 log cfu/g in fresh kernels, which was also reduced to 1.8 log cfu/g in kernels blanched at the power level of 720 W for 40 s duration.

A comparative evaluation of nutritional characteristics, physical properties, and volatile profiles of sweet corn subjected to different drying methods

AbstractBackground and objectivesFresh sweet corn is vulnerable to microbial damage and difficult to preservation at ambient temperature due to the high water and sugar contents. Therefore, in the present study, fresh sweet corn kernels were subjected to hot air drying (HAD), vacuum freeze drying (VFD), microwave drying (MD), and short‐ and medium‐wave infrared drying (SMIRD).FindingsDifferent drying ways of dehydrated sweet corns were compared in terms of physical properties, nutritional components, volatile compounds, and antioxidant capacity. After thermal treatment, sweet corn will form more volatile components and increase the flavor of sweet corn, while sweet corn treated by VFD will lose a lot of volatile components and weaken the flavor.ConclusionsThe results demonstrated that VFD products exhibited higher rehydration capacity, more nutrient retention, and better antioxidant capacity with fewer volatile compounds. A total of 63 different volatile compounds were detected in dried sweet corns. The variety of volatile substances was the maximum in the SMIRD (55), followed by HAD (35), MD (28), fresh (22), and VFD (9).Significanceand noveltyOverall, this study would be fundamental for selecting more applicable drying methods to obtain desirable quality of dried sweet corn.

Osmosis dehydration of sweet corn (Zea mays saccharata.) kernel with trehalose solution

Osmosis dehydration is a process of reducing water content by immersing the material in a hypertonic solution. It usually uses a sugar solution likes mono-saccharide or disaccharide. Trehalose is one type of disaccharide that can be used as a solute. Trehalose is able to maintain the nutrition content of food material and the aroma of horticulture products because it maintains and stabilizes complex molecules. Immersing of sweet corn kernel in trehalose solution was expected to maintain kernel sweet corn quality in relation to the next process. The objective of the research is to investigate the effects of the different immersing temperatures and trehalose concentrations on the physical quality of sweet corn. This study used solution with concentrations of 4%, 8%, and 12% trehalose. The variations of immersing temperature were 30°C, 40°C, and 50°C. The experiment was done with a factorial completely randomized design. The first factor was immersing temperature and the second factor was the concentration of trehalose solution. The data was analyzed using Duncan Multiple Range Test (DMRT) method. The temperature treatment of 50°C and trehalose concentration of 12% showed the highest weight reduction (6.18%), solid gain (4.5%), and water loss (10.38%). The lowest water content of corn kernel was also obtained in this treatment i.e 78.7%.

Effects of phosphorus fertilizer on kernel phytic acid and zinc bioavailability in sweet corn

<p id="C3">To clarify the effects of phosphorus fertilizer on nutritional characteristics of sweet corn kernels, the temporal (different filling stages) and spatial (upper, middle, and lower cob; kernel skin dregs, endosperm and embryo) variations of phytic acid (PA), phosphorus (P) and zinc (Zn) contents and Zn bioavailability of sweet corn kernels and their responses to exogenous phosphorus fertilizer were investigated using filed phosphorus fertilizer experiment (P fertilizer location experiment for sweet corn genotypes and P fertilizer level experiment). The results were as follows: P fertilizer mainly inhibited Zn bioavailability by suppressing Zn concentration in sweet corn kernels, and increased PA concentrations concurrently. P fertilizer input showed significant effects on the accumulation of PA, P, and Zn (mg plant^-1) after 16-24 days of silking, while inhibitory effects were detected on Zn bioavailability at different kernel filling stages. There was no significant difference in the kernel of PA (g kg^-1) and zinc bioavailability among different cob positions under medium P treatment. However, the high P level significantly improved the accumulation of PA in the middle and lower cob, while the inhibitory effect was found on the kernel of Zn concentration and Zn bioavailability at all cob positions. Among different parts of the kernel (skin dregs, endosperm, and embryo), the concentrations of PA, P, and Zn were the highest values in the embryo and their accumulation were the highest value in the endosperm, while Zn bioavailability was also the highest in the embryo. High P treatment significantly increased PA and P concentrations and decreased Zn concentration and its bioavailability at different kernel positions. Hence, optimized phosphorus fertilizer application could promote kernel Zn accumulation, while excessive P fertilizer input significantly increased PA accumulation at different filling stages, as well as in the endosperm and embryo, and eventually had a significant inhibitory effect on kernel Zn bioavailability in sweet corn at different cob and kernel positions. This study provides a theoretical reference for the biofortification of Zn in sweet corn seeds.

Comparative analysis of the chemical composition and size of starch granules in grain between diploid and tetraploid sweetcorn cultivars

Background. Improving the taste and nutritional value of sweetcorn using genetic selection techniques is an important trend. The tetraploid sugary maize cultivar ‘Baksanskaya sakharnaya’ (k-23426) has a number of advantages in terms of taste and marketability over traditional diploid varieties.The purpose of the research was to identify the distinctive biochemical characteristics that affect the taste of this cultivar in comparison with the diploid reference (cv. ‘Rannyaya Lakomka’, с-1775).Materials and methods. The differences in phenotypic traits between diploid (2n) and tetraploid (4n) maize plants were assessed. Infrared spectroscopy was used to study the difference in the biochemical composition of kernels in terms of protein, starch and oil content. Accumulation of metabolites in a dry kernel was studied using gas–liquid chromatography with mass spectrometry.Results. Comparison of the phenotypic traits in 2n and 4n sweetcorn plants showed that 4n had a better ear structure, protein and oil content. Analysis of metabolites showed that quantitative indicators of chemical components changed in kernels of the 4n sweetcorn without changing the qualitative composition. The chemical composition of the metabolites in 4n sweetcorn grain was characterized by an increase in the synthesis of most organic acids and protein amino acids, phosphoric acid, fatty acids, some monosaccharides, phenolic compounds, and phytosterols. A decrease in the content of most polyhydric alcohols, disaccharides, trisaccharides, some monosaccharides, and phenolic compounds was observed. An inhibitory effect of a su2 gene dose on the size of starch granules was found. Conclusion. The studies showed the advantage of the 4n sweetcorn over the 2n one due to its improved ear structure and biochemical composition, which positively affected the taste qualities.