Importance of binary and ternary complex formation on the functional and nutritional properties of legume proteins in presence of phytic acid and calcium

Nowadays, legumes are considered as a good source of plant-based proteins to replace animal ones. They are more favorable regarding environmental aspects and health benefits, therefore many people consider moving toward a greener diet. Interestingly, recent consumer trends are promoting pea and faba bean as alternatives to soybean. Both are rich in protein and a good source of essential nutrients and minerals (calcium). However, these advantages can be partially impaired due to their high phytic acid content. This natural polyphosphate is a major antinutrient in plant-based foods, as it can bind minerals (particularly calcium) and proteins, thereby reducing their digestibility and subsequent bioavailability. Indeed, complexes formed are insoluble and limiting the absorption of nutrients, thus lowering the nutritional value of pulses. To understand and overcome these issues, the present review will refine specific mechanisms involved in assemblies between these three essential compounds in legumes as soluble/insoluble binary or ternary complexes. Molecular interactions are influenced by the environmental medium including pH, ionic strength and molar concentrations modulating the stability of these complexes during protein extraction. Protein/phytic acid/calcium complexes stability is of high relevance for food processing affecting not only structure but also functional and nutritional properties of proteins in legume-based foods.

A study on Sr/Zn phytate complexes: structural properties and antimicrobial synergistic effects against Streptococcus mutans

Phytic acid (PA) is an abundant natural plant component that exhibits a versatility of applications benefited from its chemical structure, standing out its use as food, packing and dental additive due to its antimicrobial properties. The capacity of PA to chelate ions is also well-established and the formation and thermodynamic properties of different metallic complexes has been described. However, research studies of these compounds in terms of chemistry and biological features are still demanded in order to extend the application scope of PA complexes. The main goal of this paper is to deepen in the knowledge of the bioactive metal complexes chemistry and their bactericide activity, to extend their application in biomaterial science, specifically in oral implantology. Thus, this work presents the synthesis and structural assessment of two metallic phytate complexes bearing the bioactive cations Zn2+ and Sr2+ (ZnPhy and SrPhy respectively), along with studies on the synergic biological properties between PA and cations. Metallic phytates were synthesized in the solid-state by hydrothermal reaction leading to pure solid compounds in high yields. Their molecular formulas were C6H12024P6Sr4·5H2O and C6H12024P6Zn6·6H2O, as determined by ICP and HRES-TGA. The metal coordination bond of the solid complexes was further analysed by EDS, Raman, ATR-FTIR and solid 13C and 31P-NMR spectroscopies. Likewise, we evaluated the in vitro ability of the phytate compounds for inhibiting biofilm production of Streptococcus mutans cultures. Results indicate that all compounds significantly reduced biofilm formation (PA < SrPhy < ZnPhy), and ZnPhy even showed remarkable differences with respect to PA and SrPhy. Analysis of antimicrobial properties shows the first clues of the possible synergic effects created between PA and the corresponding cation in different cell metabolic processes. In overall, findings of this work can contribute to expand the applications of these bioactive metallic complexes in the biotechnological and biomedical fields, and they can be considered for the fabrication of anti-plaque coating systems in the dentistry field.

Enhancing Phytate Availability in Soils and Phytate-P Acquisition by Plants: A Review

Phytate (myo-inositol hexakisphosphate salts) can constitute a large fraction of the organic P in soils. As a more recalcitrant form of soil organic P, up to 51 million metric tons of phytate accumulate in soils annually, corresponding to ∼65% of the P fertilizer application. However, the availability of phytate is limited due to its strong binding to soils via its highly-phosphorylated inositol structure, with sorption capacity being ∼4 times that of orthophosphate in soils. Phosphorus (P) is one of the most limiting macronutrients for agricultural productivity. Given that phosphate rock is a finite resource, coupled with the increasing difficulty in its extraction and geopolitical fragility in supply, it is anticipated that both economic and environmental costs of P fertilizer will greatly increase. Therefore, optimizing the use of soil phytate-P can potentially enhance the economic and environmental sustainability of agriculture production. To increase phytate-P availability in the rhizosphere, plants and microbes have developed strategies to improve phytate solubility and mineralization by secreting mobilizing agents including organic acids and hydrolyzing enzymes including various phytases. Though we have some understanding of phytate availability and phytase activity in soils, the limiting steps for phytate-P acquisition by plants proposed two decades ago remain elusive. Besides, the relative contribution of plant- and microbe-derived phytases, including those from mycorrhizas, in improving phytate-P utilization is poorly understood. Hence, it is important to understand the processes that influence phytate-P acquisition by plants, thereby developing effective molecular biotechnologies to enhance the dynamics of phytate in soil. However, from a practical view, phytate-P acquisition by plants competes with soil P fixation, so the ability of plants to access stable phytate must be evaluated from both a plant and soil perspective. Here, we summarize information on phytate availability in soils and phytate-P acquisition by plants. In addition, agronomic approaches and biotechnological strategies to improve soil phytate-P utilization by plants are discussed, and questions that need further investigation are raised. The information helps to better improve phytate-P utilization by plants, thereby reducing P resource inputs and pollution risks to the wider environment.

Amino acid digestibility and metabolisable energy of spring and winter faba beans grown on two sites and effects of dehulling in caecectomised laying hens

BACKGROUND

The variation in amino acid (AA) digestibility and metabolisable energy (ME_N ) in four spring and four winter faba bean genotypes differing in vicine/convicine (V/C) concentrations grown on two sites was investigated in caecectomised LSL-Classic laying hens. Effects of dehulling one faba bean genotype were also examined. Diets containing one out of 17 faba bean variants each and a basal diet were fed to ten caecectomised laying hens in a row-column design to achieve five replicates per diet.

RESULTS

Ranges and levels of digestibility of the hulled variants differed widely among AA with the lowest and highest range determined for Arg (90-93%) and Cys (-12-65%), respectively. ME_N ranged between 10.3 and 12.3 MJ kg^-1 dry matter. Lower ME_N and digestibility of Cys, Glx, Phe, Pro, Tyr, and Val (P < 0.050) was determined for the winter genotypes grown in Nimtitz compared to the other variants. Digestibility of Ser was lower for the spring than for the winter genotypes (P < 0.050). Negative correlations with AA digestibility were determined for phytate, but not for tannin and V/C concentrations (P < 0.050). Negative correlations between tannin fractions and ME_N were weak (P = 0.082-0.099). Dehulling increased ME_N by 1.8 MJ kg^-1 dry matter and raised the digestibility of Pro, His, and Glx (P < 0.050).

CONCLUSIONS

The results indicated that the digestible AA and ME_N supply of laying hens was increased by using low phytate faba beans while breeding for low V/C genotypes did not affect AA digestibility or ME_N . Dehulling increased ME_N and the digestibility of some AA. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Mitigation of antinutritional factors and protease inhibitors of defatted winged bean-seed proteins using thermal and hydrothermal treatments: Denaturation/unfolding coupled hydrolysis mechanism

The inactivation of antinutritional factors, protease inhibitors within winged bean protein was induced by two respective method treatments. The physical method based on steam vapor that was conducted using an autoclave and chemical method consisting on pH-gradients of buffer solutions prepared at respective acidic pH, neutral pH and alkaline pH ranges. The activity of remaining protease inhibitors of bowman birk inhibitor (BBI), and kunitz-trypsin inhibitor (KTI) after and before treatments was enzymatically confirmed using relevant antagonistic trypsin and combined trypsin-α-chymotrypsin digests. The resulting molecular assembly indicating an interval molecular relaxation range of °0.16 < °DA < °0.2 corresponding to reconformation in protein units with volume-mass changes of -2.17 < ∂v' < +2.17 and with denaturation/unfolding efficiency based on heat capacity ΔCp of 36.36 < DE/UF% < 54.67. These structural changes had a great benefit in determining and producing functional protein hydrolysates.

Assessment of Biofortification Approaches Used to Improve Micronutrient-Dense Plants That Are a Sustainable Solution to Combat Hidden Hunger

Malnutrition causes diseases, immune system disorders, deterioration in physical growth, mental development, and learning capacity worldwide. Micronutrient deficiency, known as hidden hunger, is a serious global problem. Biofortification is a cost-effective and sustainable agricultural strategy for increasing the concentrations or bioavailability of essential elements in the edible parts of plants, minimizing the risks of toxic metals, and thus reducing malnutrition. It has the advantage of delivering micronutrient-dense food crops to a large part of the global population, especially poor populations. Agronomic biofortification and biofertilization, traditional plant breeding, and optimized fertilizer applications are more globally accepted methods today; however, genetic biofortification based on genetic engineering such as increasing or manipulating (such as CRISPR-Cas9) the expression of genes that affect the regulation of metal homeostasis and carrier proteins that serve to increase the micronutrient content for higher nutrient concentration and greater productivity or that affect bioavailability is also seen as a promising high-potential strategy in solving this micronutrient deficiency problem. Data that micronutrients can help strengthen the immune system against the COVID-19 pandemic and other diseases has highlighted the importance of tackling micronutrient deficiencies. In this study, biofortification approaches such as plant breeding, agronomic techniques, microbial fertilization, and some genetic and nanotechnological methods used in the fight against micronutrient deficiency worldwide were compiled.

Dietary Phosphorus and Calcium Utilization in Growing Pigs: Requirements and Improvements

The sustainability of animal production relies on the judicious use of phosphorus (P). Phosphate, the mined source of agricultural phosphorus supplements, is a non-renewable resource, but phosphorus is essential for animal growth, health, and well-being. P must be provided by efficient and sustainable means that minimize the phosphorus footprint of livestock production by developing precise assessment of the bioavailability of dietary P using robust models. About 60% of the phosphorus in an animal's body occurs in bone at a fixed ratio with calcium (Ca) and the rest is found in muscle. The P and Ca requirements must be estimated together; they cannot be dissociated. While precise assessment of P and Ca requirements is important for animal well-being, it can also help to mitigate the environmental effects of pig farming. These strategies refer to multicriteria approaches of modeling, efficient use of the new generations of phytase, depletion and repletion strategies to prime the animal to be more efficient, and finally combining these strategies into a precision feeding model that provides daily tailored diets for individuals. The industry will need to use strategies such as these to ensure a sustainable plant-animal-soil system and an efficient P cycle.

Biofortified Crops for Combating Hidden Hunger in South Africa: Availability, Acceptability, Micronutrient Retention and Bioavailability

In many poorer parts of the world, biofortification is a strategy that increases the concentration of target nutrients in staple food crops, mainly by genetic manipulation, to alleviate prevalent nutrient deficiencies. We reviewed the (i) prevalence of vitamin A, iron (Fe) and zinc (Zn) deficiencies; (ii) availability of vitamin A, iron and Zn biofortified crops, and their acceptability in South Africa. The incidence of vitamin A and iron deficiency among children below five years old is 43.6% and 11%, respectively, while the risk of Zn deficiency is 45.3% among children aged 1 to 9 years. Despite several strategies being implemented to address the problem, including supplementation and commercial fortification, the prevalence of micronutrient deficiencies is still high. Biofortification has resulted in the large-scale availability of βcarotene-rich orange-fleshed sweet potatoes (OFSP), while provitamin A biofortified maize and Zn and/or iron biofortified common beans are at development stages. Agronomic biofortification is being investigated to enhance yields and concentrations of target nutrients in crops grown in agriculturally marginal environments. The consumer acceptability of OFSP and provitamin A biofortified maize were higher among children compared to adults. Accelerating the development of other biofortified staple crops to increase their availability, especially to the target population groups, is essential. Nutrition education should be integrated with community health programmes to improve the consumption of the biofortified crops, coupled with further research to develop suitable recipes/formulations for biofortified foods.

Improving Nutritional and Functional Quality by Genome Editing of Crops: Status and Perspectives

Genome-editing tools including meganucleases, zinc finger nucleases, transcription activator-like effector nucleases and clustered regularly interspaced short palindromic repeats (CRISPR) system have been applied to improve the quality of staple, oilseed, and horticultural crops with great accuracy and efficiency compared to conventional breeding. In particular, the CRISPR method has proven to be a feasible, cost-effective and versatile tool allowing precise and efficient editing of plant genomes in recent years, showing great potential in crop improvement. Until now, various genome-edited crops with enhanced commercial value have been developed by not only global companies but also small laboratories in universities, suggesting low entry barriers with respect to manpower and capital. In this study, we review the current applications of genome editing technologies to improve the nutritional and functional quality and preferred traits of various crops. Combining this rapidly advancing genome-editing technology and conventional breeding will greatly extend the potential of genome-edited crops and their commercialization.

Seed targeted RNAi-mediated silencing of GmMIPS1 limits phytate accumulation and improves mineral bioavailability in soybean

Phytic acid (PA), the major phosphorus reserve in soybean seeds (60-80%), is a potent ion chelator, causing deficiencies that leads to malnutrition. Several forward and reverse genetics approaches have ever since been explored to reduce its phytate levels to improve the micronutrient and phosphorous availability. Transgenic technology has met with success by suppressing the expression of the PA biosynthesis-related genes in several crops for manipulating their phytate content. In our study, we targeted the disruption of the expression of myo-inositol-3-phosphate synthase (MIPS1), the first and the rate limiting enzyme in PA biosynthesis in soybean seeds, by both antisense (AS) and RNAi approaches, using a seed specific promoter, vicilin. PCR and Southern analysis revealed stable integration of transgene in the advanced progenies. The transgenic seeds (T4) of AS (MS14-28-12-29-3-5) and RNAi (MI51-32-22-1-13-6) soybean lines showed 38.75% and 41.34% reduction in phytate levels respectively, compared to non-transgenic (NT) controls without compromised growth and seed development. The electron microscopic examination also revealed reduced globoid crystals in the Protein storage vacoules (PSVs) of mature T4 seeds compared to NT seed controls. A significant increase in the contents of Fe2+ (15.4%, 21.7%), Zn2+ (7.45%, 11.15%) and Ca2+ (10.4%, 15.35%) were observed in MS14-28-12-29-3-5 and MI51-32-22-1-13-6 transgenic lines, respectively, compared to NT implicating improved mineral bioavailability. This study signifies proof-of-concept demonstration of seed-specific PA reduction and paves the path towards low phytate soybean through pathway engineering using the new and precise editing tools.

Plant Genome Engineering for Targeted Improvement of Crop Traits

To improve food security, plant biology research aims to improve crop yield and tolerance to biotic and abiotic stress, as well as increasing the nutrient contents of food. Conventional breeding systems have allowed breeders to produce improved varieties of many crops; for example, hybrid grain crops show dramatic improvements in yield. However, many challenges remain and emerging technologies have the potential to address many of these challenges. For example, site-specific nucleases such as TALENs and CRISPR/Cas systems, which enable high-efficiency genome engineering across eukaryotic species, have revolutionized biological research and its applications in crop plants. These nucleases have been used in diverse plant species to generate a wide variety of site-specific genome modifications through strategies that include targeted mutagenesis and editing for various agricultural biotechnology applications. Moreover, CRISPR/Cas genome-wide screens make it possible to discover novel traits, expand the range of traits, and accelerate trait development in target crops that are key for food security. Here, we discuss the development and use of various site-specific nuclease systems for different plant genome-engineering applications. We highlight the existing opportunities to harness these technologies for targeted improvement of traits to enhance crop productivity and resilience to climate change. These cutting-edge genome-editing technologies are thus poised to reshape the future of agriculture and food security.

Comparison of color, anti-nutritional factors, minerals, phenolic profile and protein digestibility between hard-to-cook and easy-to-cook grains from different kidney bean (Phaseolus vulgaris) accessions

The present study was aimed to evaluate the differences among anti-nutritional factors in relation to mineral absorption and protein digestibility of Easy-to-cook (ETC) and Hard-to-cook (HTC) grains from different kidney bean (KB) accessions.HTC grains showed lower a* (redness to yellowness) and b* (greenness to blueness) values and L* value than ETC grains. HTC grains had significantly higher Ca and Zn and lower Cu, Mn and Fe than ETC grains. ETC and HTC grains showed significant variation in mineral, total phenolic content (TPC), tannin and phytic acid content. TPC and tannin content were significantly higher for HTC grains, on the contrary phytic acid content was lower than counterpart ETC grains. Protein and in vitro protein digestibility (IVPD) also varied significantly between HTC and ETC grains and was found to be lower for HTC grains. Majority of phenolic compounds (PCs) were present in bound state in both ETC and HTC grains. Moreover, HTC grains showed higher amount of chlorogenic acid and catechin content than ETC grains in bound form. ETC and HTC grains from dark color accessions showed higher catechin content.

Replacing electrolytic iron in a fortification-mix with NaFeEDTA increases both iron and zinc availabilities in traditional African maize porridges

While replacing electrolytic iron with NaFeEDTA in multi-micronutrient fortification-mixes is a popular option, there is no information about the effect on the iron and zinc availabilities in African staple foods. This study evaluated the effects of adding a multi-micronutrient fortification-mix, with no iron, electrolytic iron or NaFeEDTA on the availabilities of iron and zinc from thick and fermented special-grade maize porridges using a Caco-2 cell model. Replacing electrolytic iron with NaFeEDTA significantly (p ⩽ 0.05) increased iron and, importantly zinc, availabilities in both the thick (2.16% vs. 1.45% and 2.51% vs. 2.29%, respectively) and fermented (3.35% vs. 2.66% and 3.04% vs. 2.61%, respectively) porridges. Some of the NaFeEDTA complexes perhaps partially dissociated because of pH changes during simulated digestion, binding with zinc and increasing its availability. NaFeEDTA in a multi-micronutrient fortification-mix, added to less refined, high phytate maize meal, would be more effective than electrolytic iron in addressing both iron and zinc deficiencies in low socio-economic populations of sub-Saharan Africa.

Reduction of phytic acid and enhancement of bioavailable micronutrients in food grains

More than half of the world populations are affected by micronutrient malnutrition and one third of world's population suffers from anemia and zinc deficiency, particularly in developing countries. Iron and zinc deficiencies are the major health problems worldwide. Phytic acid is the major storage form of phosphorous in cereals, legumes, oil seeds and nuts. Phytic acid is known as a food inhibitor which chelates micronutrient and prevents it to be bioavailabe for monogastric animals, including humans, because they lack enzyme phytase in their digestive tract. Several methods have been developed to reduce the phytic acid content in food and improve the nutritional value of cereal which becomes poor due to such antinutrient. These include genetic improvement as well as several pre-treatment methods such as fermentation, soaking, germination and enzymatic treatment of grains with phytase enzyme. Biofortification of staple crops using modern biotechnological techniques can potentially help in alleviating malnutrition in developing countries.

Comparative studies on storage stability of ferrous iron in whole wheat flour and flat bread (naan)

Whole wheat flour was fortified with premix containing ferrous sulfate, ethylenediamine tetraacetic acid and folic acid (20.0:20.0:1.5 ppm) and was stored at ambient temperature for 60 days. Naans (flat bread) were prepared from 0 ppm, 25 ppm, 50 ppm and 75 ppm ferrous iron-fortified flour samples at 10-day intervals and were analyzed for physicochemical constants and sensory evaluation. It was observed that flour containing 75 ppm ferrous sulfate contained the highest iron residues. The total iron in flour samples showed no significant difference, while ferrous iron significantly decreased in fortified flour (0.53-3.08%) and in the naans (0.42-3.48%) because of its oxidation to ferric iron during storage. The phytic acid content decreased (0.886-0.810%) significantly during the same storage period. Iron levels affected some sensory characteristics significantly (P < or =0.05), including color, texture, flexibility, chewability and overall acceptability of the naans, but not taste and flavor. The sensory attributes of naans illustrated that naans containing 50 ppm ferrous iron are more acceptable than those prepared with 75 ppm ferrous iron.

Efficacy of iron-fortified whole maize flour on iron status of schoolchildren in Kenya: a randomised controlled trial

BACKGROUND

Sodium iron edetic acid (NaFeEDTA) might be a more bioavailable source of iron than electrolytic iron, when added to maize flour. We aimed to assess the effect, on children's iron status, of consumption of whole maize flour fortified with iron as NaFeEDTA or electrolytic iron.

METHODS

516 children, aged 3-8 years, from four schools in Marafa, Kenya, were randomly assigned to four groups. All were given the same amount of porridge five times a week. The porridge for one group was made from unfortified whole maize flour; for the other three groups it was fortified with either high-dose NaFeEDTA (56 mg/kg), low-dose NaFeEDTA (28 mg/kg), or electrolytic iron (56 mg/kg). Concentrations of haemoglobin, plasma ferritin, and transferrin receptor were analysed in samples taken at baseline and at the end of the 5-month intervention. The primary outcome was iron-deficiency anaemia. We analysed data on an intention-to-treat basis. This trial is registered with ClinicalTrials.gov, number NCT00386074.

FINDINGS

The prevalence of iron-deficiency anaemia in children given unfortified flour was 10%. Compared with placebo, the prevalence of iron-deficiency anaemia in children given flour fortified with high-dose NaFeEDTA, low-dose NaFeEDTA, and electrolytic iron changed by -89% (95% CI -97% to -49%), -48% (-77% to 20%), and 59% (-18% to 209%), respectively. Consumption of high-dose NaFeEDTA improved all measured iron-status indicators. Low-dose NaFeEDTA decreased the prevalence of iron deficiency but did not noticeably change the prevalence of anaemia. Electrolytic iron did not improve any of these iron-status indicators. Children who were iron-deficient at baseline benefited more from high-dose and low-dose NaFeEDTA than those with sufficient iron at baseline.

INTERPRETATION

Consumption of whole maize flour fortified with NaFeEDTA caused modest, dose-dependent improvements in children's iron status. Fortification with electrolytic iron did not improve their iron status. Therefore, in high-phytate flours, NaFeEDTA is more suitable than electrolytic iron for supplementation of iron in the diet.