“Antioxidant activity and characterization of protein fractions and hydrolysates from normal and quality protein maize kernels”

Maize kernel nutritional quality-an old challenge for modern breeders

MAIN CONCLUSION

This article offers a comprehensive overview of the starch, protein, oil, and carotenoids content in maize kernels, while also outlining future directions for research in this area. Maize is one of the most important cereal crops globally. Maize kernels serve as a vital source of feed and food, and their nutritional quality directly impacts the dietary intake of both animals and humans. Maize kernels contain starch, protein, oil, carotenoids, and a variety of vitamins and minerals, all of which are important for maintaining life and promoting health. This review presents the current understanding of the content of starch, protein, amino acids, oil, and carotenoids in maize kernels, while also highlighting knowledge gaps that need to be addressed.

Calcium and Magnesium Regulation of Kernel Sugar Content in Maize: Role of Endogenous Hormones and Antioxidant Enzymes

Ca and Mg are essential micronutrients for plant growth, and they play a crucial role in plant development and responses to adversity by influencing the activities of endogenous hormones and antioxidant enzymes. However, the specific mechanisms through which calcium (Ca) and magnesium (Mg) regulate the kernel sugar content through endogenous hormones and antioxidant enzymes remain unclear. In this study, we analyzed the impact of Ca and Mg on the physiology of maize leaves and kernel quality by determining the activities of antioxidant enzymes and endogenous hormones, and the kernel sugar content in maize leaves when supplemented with different levels of Ca and Mg. Our main findings were as follows: (1) Elevated Mg levels augmented superoxide dismutase (SOD) activity, bolstering antioxidant defenses, whereas low Ca and Mg levels diminished SOD activity. High Ca levels enhanced catalase (CAT) activity during kernel development. Low-Ca conditions stimulated gibberellin (GA) synthesis, while high-Ca and high-Mg conditions suppressed it. High Mg levels also elevated abscisic acid (ABA) levels, potentially improving stress tolerance. (2) High Ca levels increased the reducing sugar content in kernels, augmenting the energy supply, while both low and high Mg levels increased soluble sugars, with low Mg levels specifically enhancing the sucrose content, which is a critical energy reserve in plants. (3) CAT exerted a pivotal regulatory role in the sugar accumulation in maize kernels. GA, under the influence of Ca, modulated the sucrose and soluble sugar contents by inhibiting CAT, whereas ABA, under the influence of Mg, promoted CAT activity, thereby affecting the kernel sugar content. This study reveals a new mechanism through which the addition of Ca and Mg regulate the sugar content in maize kernels by affecting endogenous hormones and antioxidant enzyme activities. These findings not only enhance our understanding of the role of micronutrients in plant growth and development but also provide new strategies for improving crop yield and stress tolerance.

Harnessing the nutritional profile and health benefits of millets: a solution to global food security problems

India is dealing with both nutritional and agricultural issues. The maximum area of agricultural land with irrigation capabilities has been largely utilized, while the amount of dry land is expanding. The influence is distinct on farmer's livelihoods and earnings, which ultimately affects nutritional security. In order to attain nutritional security and the goal of SDG (Sustainable Development Goals), millets are sustainable solutions, with respect to high nutritional content, bioactive and medicinal properties, and climate resilience. The nutrient profile of millet includes 60%-70% carbohydrate content, 3.5%-5.2% fat, and 7.52%-12.1% protein sources. A wide spectrum of amino acids, including cysteine, isoleucine, arginine, leucine, tryptophan, lysine, histidine, methionine, tyrosine, phenylalanine, threonine, and valine are generally present in millets. Mineral content in millets includes calcium, phosphorus, potassium, sodium, and magnesium. Additionally, millets are an excellent source of bioactive molecules such as polyphenol, phenolic acid, flavonoids, active peptides, and soluble fiber, which have a wide range of therapeutic applications, including the prevention of free radical damage, diabetes, anti-microbial, anti- biofilm, and anti-cancer effects. This review will focus on the nutritional profile and health benefits of millet considering the present-day food security problems.

Antioxidant, anti-inflammatory, hypoglycemic, and anti-hyperglycemic activity of chickpea protein hydrolysates evaluated in BALB-c mice

Chickpea (ICC3761) protein hydrolysates have shown high in vitro antioxidant activity (AoxA) and antidiabetic potential. The aim of this study was to evaluate the in vivo activities (i.e., antioxidant, anti-inflammatory, hypoglycemic, and anti-hyperglycemic) of chickpea albumin hydrolysates (CAH) obtained with alcalase and pepsin-pancreatin (fractions ≤ 10 kDa). The CAH were analyzed for degree of hydrolysis (DH), electrophoretic and chromatographic profiles, and in vitro AoxA (2,2'-azino-bis(3-ethylbenzothiazolin)-6-sulfonic acid [ABTS], 2,2-diphenyl-1-pycrilhydrazyl [DPPH]). They were also evaluated for AoxA, anti-inflammatory and hypo- and anti-hyperglycemic activities in BALB-c mice. The DH was 20% for the alcalase CAH and 50% for the pepsin-pancreatin CAH, while the AoxA by ABTS (1 mg/mL) was 64.8% and 64.9% and by DPPH (5 mg/mL) was 48.0% and 31.1%. In the in vivo AoxA assay, mice of non-damaged control and those treated with both CAH showed similar alkaline phosphatase values, control and pepsin-pancreatin treated groups had similar malondialdehyde levels, while treated and non-damaged control groups had higher glutathione levels than the damaged control. Liver histopathology revealed that the pepsin-pancreatin CAH mitigated most of the pathological changes associated with the induced oxidative damage. Both CAH (2 mg/ear) reduced croton oil-induced ear edema in mice. The α-glucosidase inhibition of CAH (100 mg/mL) was 31.1% (alcalase) and 52.4% (pepsin-pancreatin). Mice treated with alcalase CAH (100 mg/mL) and glibenclamide exhibited similar hypoglycemic activities, whereas only those treated with the pepsin-pancreatin CAH (200 mg/kg body weight) showed anti-hyperglycemic activity. The results indicate that CAH can be used as a source of bioactive peptides with antioxidant, anti-inflammatory, hypoglycemic, and anti-hyperglycemic activities.

Relation of amino acid composition, hydrophobicity, and molecular weight with antidiabetic, antihypertensive, and antioxidant properties of mixtures of corn gluten and soy protein hydrolysates

New mixed Alcalase-hydrolysates were developed using corn gluten meal (CP) and soy protein (SP) hydrolysates, namely CPH, SPH, SPH30:CPH70, SPH70:CPH30, and SPH50:CPH50. Amino acid profile, surface hydrophobicity (H 0), molecular weight (MW) distribution, antioxidant activity, angiotensin-converting enzyme (ACE), α-amylase, and α-glucosidase inhibitory activities, and functional characteristics of hydrolysates were determined. Hydrolysis changed the amount of hydrophilic and hydrophobic amino acid composition and significantly increased the H 0 values of hydrolysates, especially for CPH. The DPPH radical scavenging activity (RSA) was higher for CPH, SPH30:CPH70, and SPH50:CPH50 than SPH and SPH70:CPH30. Moreover, SPH, SPH70:CPH30, and SPH50:CPH50 showed lower MW than CPH, and this correlated with the higher hydrophilicity, and ABTS and hydroxyl RSA values obtained for SPH and the mixed hydrolysates with predominantly SPH. SPH70:CPH30 exhibited higher ACE, α-glucosidase, and α-amylase inhibitory activities among all samples due to its specific peptides with high capacity to interact with amino acid residues located at the enzyme active site and also low binding energy. At 15% degree of hydrolysis, both SPH and CPH showed enhanced solubility at pH 4.0, 7.0 and 9.0, emulsifying activity, and foaming capacity. Taken together, SPH70:CPH30 displayed strong antioxidant, antihypertensive, and antidiabetic attributes, emulsifying activity and stability indexes, and foaming capacity and foaming stability, making it a promising multifunctional ingredient for the development of functional food products.

Nutritional composition and bioactive properties of the wholegrain flour obtained from maize inbred lines

The aim of this study was to assess the chemical composition and bioactive properties of the wholegrain flour obtained from eleven maize inbred lines to identify genotypes with increased potential for the development of hybrids with high nutritional and functional value, suitable for food production. The maize inbreds, including seven standard yellow, two QPM (quality protein maize) and two lines for red kernel hybrids, were grown in the experimental field of the Maize Research Institute at the location of Zemun Polje, Serbia. Wholegrain maize flour was got by grinding the maize grain in a laboratory mill. The assessment of the chemical composition and content of certain bioactive compounds, as well as the total antioxidant capacity, was conducted using standard laboratory procedures. The highest starch content (73.73%) was determined in line L8, while line L10 had the highest protein content (12.82%). Among soluble proteins, the a-zein fraction was dominant in most of the lines, ranging from 0.92% to 3.57%. The highest content of total fibres (NDF) was determined in red kernel line L9 (15.77%). Line L8 was the richest in total carotenoids (21.08 mg bCE/g d.m.), while line L7 had the highest total antioxidant capacity (34.30 mmol Trolox/kg d.m.), which can be explained by the presence of anthocyanins in the red grain. Line L1 had the highest content of total sugars (3.36%), and line L4 had the lowest (1.44%). Most of the samples of inbred lines investigated in this study showed good quality parameters regarding chemical composition and bioactive properties. The obtained results may provide some valuable guidelines needed in the following stages of maize breeding and open up various possibilities for the utilization of wholegrain maize flour in the food industry.

Production, health-promoting properties and characterization of bioactive peptides from cereal and legume grains

The search for bioactive components for the development of functional foods and nutraceuticals has received tremendous attention. This is due to the increasing awareness of their therapeutic potentials, such as antioxidant, anti-inflammatory, antihypertensive, anti-cancer properties, etc. Food proteins, well known for their nutritional importance and their roles in growth and development, are also sources of peptide sequences with bioactive properties and physiological implications. Cereal and legume grains are important staples that are processed and consumed in various forms worldwide. However, they have received little attention compared to other foods. This review therefore is geared towards surveying the literature for an appraisal of research conducted on bioactive peptides in cereal and legume grains in order to identify what the knowledge gaps are. Studies on bioactive peptides from cereal and legume grains are still quite limited when compared to other food items and most of the research already carried out have been done without identifying the sequence of the bioactive peptides. However, the reports on the antioxidative, anticancer/inflammatory, antihypertensive, antidiabetic properties show there is much prospect of obtaining potent bioactive peptides from cereal and legume grains which could be utilized in the development of functional foods and nutraceuticals.

Corn distillers solubles as a novel bioresource of bioactive peptides with ACE and DPP IV inhibition activity: characterization, in silico evaluation, and molecular docking

This study aimed to investigate the biological potential of underutilized and low-value corn distillers solubles, containing a unique unexplored blend of heat-treated corn and yeast proteins, from the bioethanol industries, by bioinformatic and biochemical approaches. Protein hydrolysates were produced by applying four commercially accessible proteases, among which alcalase provided the best results in terms of yield, degree of hydrolysis, molecular weight, number of proteins, bioactive peptides, and deactivation against anti-angiotensin I-converting enzyme (ACE) and anti-dipeptidyl peptidase IV (DPP IV). The optimal conditions to produce anti-ACE and anti-DPP IV peptides were using alcalase for 10.82 h and an enzyme : substrate ratio of 7.90 (%w/w), with inhibition values for ACE and DPP IV of 98.76 ± 1.28% and 34.99 ± 1.44%, respectively. Corn (α-zein) and yeast (glyceraldehyde-3-phosphate dehydrogenase) proteins were mainly suitable, upon enzymolysis, for the release of bioactive peptides. The peptides DPANLPWG, FDFFDNIN, WNGPPGVF, and TPPFHLPPP inhibited ACE more effectively as verified with binding energies of -11.3, -11.6, -10.5, and -11.6 kcal mol^-1, respectively, as compared to captopril (-6.38 kcal mol^-1). Compared with the binding energy of sitagliptin (-8.6 kcal mol^-1), WNGPPGVF (-9.6 kcal mol^-1), WPLPPFG (-9.8 kcal mol^-1), LPPYLPS (-9.7 kcal mol^-1), TPPFHLPPP (-10.1 kcal mol^-1), and DPANLPWG peptides (-10.1 kcal mol^-1) had greater inhibition potential against DPP IV. The peptides impeded ACE and DPP IV majorly via hydrophobic and hydrogen linkage interactions. The key amino acids TYR⁵²³, GLU³⁸⁴, and HIS³⁵³ were bound to the catalytic sites of ACE and GLN⁵⁵³, GLU²⁰⁶, PHE³⁶⁴, VAL³⁰³, and THR³⁰⁴ were bound to the DPP IV enzyme. The PHs can be used as ingredients in the feed or food industries with possible health advantages.

Production and antioxidant capacity of bioactive peptides from plant biomass to counteract lipid oxidation

Preventing lipid oxidation, especially with the polyunsaturated fat-based products, is a major concern in sectors as agri-food and cosmetic. Even though the efficiency of synthetic antioxidants has been recognized, both consumers and manufacturers are looking for more innovative, healthy and quality products while rejecting synthetic additives due to their concern about safety, along with their environmental impact issues. In this context, plant biomass, which have shown to be rich in compounds, have raised interest for the isolation of novel naturally occurring antioxidants. Among their myriad of molecules, bioactive peptides, which are biologically active sequence of amino acid residues of proteins, seem to be of a great interest. Therefore, the number of identified amino acids sequences of bioactive peptides from plant biomass with potential antioxidant action is progressively increasing. Thus, this review provides a description of 129 works that have been made to produce bioactive peptides (hydrolysate, fraction and/or isolate peptide) from 55 plant biomass, along with the procedure to examine their antioxidant capacity (until 2019 included). The protein name, the process, and the method to concentrate or isolate antioxidant bioactive peptides, along with their identification and/or specificity were described. Considering the complex, dynamic and multifactorial physico-chemical mechanisms of the lipid oxidation, an appropriate in-vitro methodology should be better performed to efficiently probe the antioxidant potential of bioactive peptides. Therefore, the results were discussed, and perspective for antioxidant applications of bioactive peptides from plant biomass was argued.

Interfacial and emulsion-stabilizing properties of zein nanoparticles: differences among zein fractions (α-, β-, and γ-zein)

According to the solubility in the binary solvent of ethanol water, zein can be classified into α-, β-, γ-, and δ-zein, and the difference in amino acid compositions of these fractions is believed to affect their physicochemical properties and functionalities. This research comparatively analyzed main zein fractions, namely the α-zein fraction, β-zein fraction, and γ-zein fraction, on the formation, surface adsorption, and emulsifying properties of their anti-solvent-induced particles. Results showed that all zein fractions were able to form spherical particles through an anti-solvent procedure, and formed particles possessed different surface charge and surface hydrophobicity. γ-Zein fraction particles had the biggest size and lowest surface hydrophobicity, the highest interfacial adsorption speed, and formed the strongest viscoelastic interfacial film, as analyzed through the interfacial rheology results, while β-zein fraction particles exhibited the poorest interfacial activity. These physicochemical differences were reflected in their emulsifying properties, whereby the γ-zein fraction particle-stabilized emulsion had the maximum tolerance to salt (50, 100, and 200 mM NaCl) and pH (4.0, 7.0, and 9.0). The excellent interfacial properties of the γ-zein fraction presented in this research would afford a new strategy for the effective application of zein.

Effect of Lactic Acid Fermentation on Quinoa Characteristics and Quality of Quinoa-Wheat Composite Bread

The application of selected starter cultures with specific properties for fermentation may determine steady lactic acid bacteria (LAB) variety and the characteristics of fermented products that influence nutritional value, the composition of biologically active compounds and quality. The aim of this research was to evaluate the influence of different LAB on the biochemical characteristics of fermented quinoa. Moreover, total phenolic content (TPC), and the antimicrobial and antioxidant activities of protein fractions isolated from quinoa previously fermented with LAB were investigated. Quinoa additives, including quinoa fermented with Lactobacillus brevis, were incorporated in a wheat bread recipe to make nutritionally fortified quinoa-wheat composite bread. The results confirmed that L. plantarum, L. brevis, and L. acidophilus were well adapted in quinoa medium, confirming its suitability for fermentation. LAB strains influenced the acidity, L/D-lactic acid content, enzyme activity, TPC and antioxidant activity of fermented quinoa. The maximum phytase activity was determined in quinoa fermented with L. brevis. The results obtained from the ABTS radical scavenging assay of protein fractions confirmed the influence of LAB strain on the antioxidant activity of protein fractions. The addition of 5 and 10% of quinoa fermented with L. brevis did not affect the total titratable acidity of wheat bread, while 10% of fermented quinoa with L. brevis resulted in a higher specific volume. Fermented quinoa additives increased the overall acceptability of bread compared with unfermented seed additives.

In Silico Analysis and In Vitro Characterization of the Bioactive Profile of Three Novel Peptides Identified from 19 kDa α-Zein Sequences of Maize

In this study, we characterized three novel peptides derived from the 19 kDa α-zein, and determined their bioactive profile in vitro and developed a structural model in silico. The peptides, 19ZP1, 19ZP2 and 19ZP3, formed α-helical structures and had positive and negative electrostatic potential surfaces (range of -1 to +1). According to the in silico algorithms, the peptides displayed low probabilities for cytotoxicity (≤0.05%), cell penetration (10-33%) and antioxidant activities (9-12.5%). Instead, they displayed a 40% probability for angiotensin-converting enzyme (ACE) inhibitory activity. For in vitro characterization, peptides were synthesized by solid phase synthesis and tested accordingly. We assumed α-helical structures for 19ZP1 and 19ZP2 under hydrophobic conditions. The peptides displayed antioxidant activity and ACE-inhibitory activity, with 19ZP1 being the most active. Our results highlight that the 19 kDa α-zein sequences could be explored as a source of bioactive peptides, and indicate that in silico approaches are useful to predict peptide bioactivities, but more structural analysis is necessary to obtain more accurate data.

Production and Characterization of Antioxidative Hydrolysates and Peptides from Corn Gluten Meal Using Papain, Ficin, and Bromelain

There has been a growing interest in developing natural antioxidants with high efficiency and low cost. Bioactive protein hydrolysates could be a potential source of natural and safer antioxidants. The objectives of this study were to hydrolyze corn gluten meal using three plant-derived proteases, namely papain, ficin, and bromelain, to produce antioxidative hydrolysates and peptides and to characterize the antioxidant performances using both chemical assays and a ground meat model. The optimum hydrolysis time for papain was 3 h, and for ficin and bromelain was 4 h. The hydrolysates were further separated by sequential ultrafiltration to 5 hydrolysate fractions named F1 to F5 from low molecular weight (MW) (<1 kDa) to high MW range (>10 kDa), which were further characterized for TPC, free radical scavenging capacity against DPPH and ABTS, and metal chelating activity. The fraction F4 produced by papain (CH-P4), F1 produced by ficin (CH-F1), and F3 produced by bromelain (CH-B3) showed the strongest antioxidant activity and yield, respectively. These three fractions were incorporated into ground pork to determine their inhibition effects on lipid oxidation during a 16-day storage period. The inhibition effect was enhanced with the addition of higher amount of hydrolysate (e.g., 1000 vs. 500 mg/kg). The CH-P4 reduced lipid oxidation in ground meat by as much as 30.45%, and CH-B3 reduced oxidation by 27.2% at the same level, but the inhibition was only 13.83% with 1000 mg/kg of CH-F1. The study demonstrated that CGM protein hydrolysates and peptides could be used as naturally derived antioxidant in retarding lipid oxidation and improving product storage stability.