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Soybean Amino Acids in Health, Genetics, and Evaluation

  • Agricultural Research Service, Raleigh, NC 27607


Soybean is an important source of protein and amino acids for humans and livestock because of its well-balanced amino acid profile. This chapter outlines the strengths and weaknesses of soybean as a complete amino acid source as well as the relative importance of individual amino acids. Special attention is paid to the sulfur-containing amino acids, methionine and cysteine. Breeding and genetic engineering efforts are summarized to highlight previous accomplishments in amino acid improvement and potential avenues for future research. Agronomic properties and processing methods that affect amino acid levels in soybean food and feed are also explained. A brief introduction into current amino acid evaluation techniques is provided. By understanding the complexities of amino acids in soybean, protein quality for humans and livestock can be maximized.
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Provisional chapter
Soybean Amino Acids in Health, Genetics, and
William Monte Singer, Bo Zhang,
M.A. Rouf Mian and Haibo Huang
Additional information is available at the end of the chapter
© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons
Attribution License (, which permits unrestricted use,
distribution, and reproduction in any medium, provided the original work is properly cited.
William MonteSinger, BoZhang, M.A. RoufMian
and HaiboHuang
Additional information is available at the end of the chapter
Soybean is an important source of protein and amino acids for humans and livestock
because of its well-balanced amino acid prole. This chapter outlines the strengths and
weaknesses of soybean as a complete amino acid source as well as the relative importance
of individual amino acids. Special aention is paid to the sulfur-containing amino acids,
methionine and cysteine. Breeding and genetic engineering eorts are summarized to
highlight previous accomplishments in amino acid improvement and potential avenues
for future research. Agronomic properties and processing methods that aect amino
acid levels in soybean food and feed are also explained. A brief introduction into cur-
rent amino acid evaluation techniques is provided. By understanding the complexities
of amino acids in soybean, protein quality for humans and livestock can be maximized.
Keywords: essential and nonessential amino acids, soybean meal, methionine, cysteine,
sulfur-containing amino acids
1. Introduction
Soybean is one of the world’s most economically and nutritionally important crops. In 2018,
soybean were 61% of international oilseed production with 397.9 tons harvested worldwide
[1]. The United States and Brazil were the largest producers at 4545 and 4299 million bushels,
respectively, with China being the largest importer of U.S. whole soybeans valued over $3 bil-
lion U.S. [2, 3]. Soybean products, namely meal and oil, are popular in a myriad of industries
for their versatility and utility. Soybean oil provides the most versatility with uses in fuel,
solvents, candles, cosmetics, construction, and foam. However, soybean meal is the driving
© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative
Commons Attribution License (, which permits unrestricted use,
distribution, and reproduction in any medium, provided the original work is properly cited.
factor for 70% of the plant’s value with 97% of all U.S. soybean meal being used for animal
feed [4]. As such, an enormous portion of soybean’s importance lies with its nutritional capa-
bilities for livestock and humans.
Nutritionally speaking, soybeans are a highly valued protein source. Proteins are a crucial
macromolecule needed in the diets of human and livestock. However, the true signicance of
soybean protein is due to its well-balanced amino acid prole that aligns with dietary needs
of humans and animals [5]. Amino acids are the functional subunits of proteins that, when
linked together in dierent orders, generate the variety of proteins critical to life. Amino acids
are also important intermediates for many biosynthesis pathways [6]. Deciencies in single
or multiple amino acids can negatively impact an individual’s growth and development [7,
8]. Intriguingly, an excess of certain amino acids has also been shown to worsen feed intake,
nitrogen eciency, and growth rate in livestock [911]. The importance of amino acid levels
on human health has also been well documented [12, 13].
Amino acids are characterized by having amine (NH2) and carboxyl (COOH) functional
groups as well as a “R-group” that is unique to each amino acid [14]. Amino acids are abun-
dant in both proteinogenic (protein-incorporated) and non-proteinogenic forms [15]. The 20
common, proteinogenic amino acids are generally the focus of research in soybeans as they
are the dening nutritive feature. Of those twenty, nine amino acids are essential for humans
to consume. Livestock usually require these same amino acids from feed and might require
others because of their biological systems [16]. Soybeans contain some level of all nine essential
amino acids which creates a suitable nutritional foundation for livestock feed and human food.
2. Essential amino acids
Essential amino acids are ones that living organisms are unable to biosynthesize themselves
and must obtain from their food source [7, 12, 16]. Therefore, in this term, “essential” refers to
the amino acid requirements in dietary ingredients. The nine standard essential amino acids
for humans present in soybean are: histidine, isoleucine, leucine, lysine, methionine, phenyl-
alanine, threonine, tryptophan, and valine [17]. Arginine is regularly considered an essential
amino acid for sh, poultry and sometimes swine due to absent or decient urea cycles [9,
16]. Poultry and reptiles also require dietary glycine because of diering waste excretion
pathways [16]. While crude protein content is normally recognized as the driving nutritional
factor for soybean meal, these essential amino acids provide true utility.
It has long been recommended that protein quality is based upon essential amino acid content.
However, for many reasons, animal feed and human food markets have only recently begun
assessing accordingly [5, 18, 19]. Equipment required for accurate amino acid measurement
and the diversity of markets for amino acids makes it dicult for supply chain evaluators like
elevator operators to appraise amino acid content on site. To some degree, the well-balanced
soybean amino acid prole also devalues the need to measure individual amino acid levels.
Since all essential amino acids are present, less aention is paid to decient amino acids such
as methionine and tryptophan [17, 20].
Soybean for Human Consumption and Animal Feed2
Deciencies in soybean’s essential amino acid prole has led to a large section of the livestock
industry focusing on feed mixing and supplementation. Rationing with other feed sources
such as cereal grain and synthetic amino acid augmentation can eectively resolve the issue.
Although, this comes with economic and environmental problems. Supplementing amino
acids adds costs to farmers. For example, the average cost for amino acids supplementation
for dairy farmers is 20 cents per head per day [21]. Maximizing crude protein for a growth
limiting factor also negatively impacts livestock nitrogen-use-eciency and environmental
nitrogen outputs [8, 22]. Synthetic amino acid production can produce hazardous environ-
mental waste and synthetic methionine, the most limiting soybean amino acid for poultry,
has also been banned for organic poultry production [20, 23]. Movement towards sustainable
agriculture will pressure the feed industry to alter how soybean meal is enhanced for essential
amino acid livestock maximization. Furthermore, the increasing popularity of meat-less diets
in humans will create new markets for soybean’s well-balanced amino acid prole.
3. Nonessential amino acids
Nonessential amino acids should not be misconstrued as unimportant amino acids. Of the 20
proteinogenic amino acids, those considered nonessential are still necessary for living organ-
isms. Healthy organisms are able to biosynthesize them and are not required from food and
feed consumption. The 20 standard nonessential amino acids for humans found in soybean
are: arginine, alanine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine,
proline, serine, and tyrosine [2426]. As previously mentioned, the necessity of amino acids
such as arginine and glycine can dier amongst species. Some nonessential amino acids are
also aected by the presence and amounts of essential amino acids.
Cysteine not provided from food consumption is directly biosynthesized from methionine
via trans-sulfuration [16, 2730]. Consequently, if cysteine is not provided in the diet, then
enough methionine must be provided to compensate for both amino acid needs. For that
reason, feed research for poultry occasionally measures methionine and cysteine jointly [10,
31, 32]. Tyrosine is also directly formed from phenylalanine via hydroxylation [16, 29, 33].
Other amino acids like arginine, glycine, and proline can be required from the diet when
animals are young, old, sick, or otherwise decient in body protein regulation. As human
and livestock diets become more sustainably plant-based, it will become more important to
evaluate nonessential amino acids, specically the ones immediately aected by essential
amino acids.
4. Proteinogenic sulfur-containing amino acids
The two proteinogenic sulfur-containing amino acids, methionine and cysteine, are critical to
evaluating soybean meal as food and feed. While present in soybean, methionine and cysteine
levels are both inadequate for consumer needs [8, 20, 24]. Similar to research determinations,
the nutritional requirements for methionine and cysteine intake are often grouped together
Soybean Amino Acids in Health, Genetics, and Evaluation 3
as overall sulfur consumption from protein. Adult humans are recommended to intake 910–
1120 mg methionine and cysteine (based on body weight) per day [13]. For livestock, sulfur
amino acids recommendations can vary based on species, age, end-use, and diet formulation.
The importance of dietary sulfur amino acids for livestock is greatly emphasized in literature,
especially with soybean meal as base feed [8, 20, 34, 35].
Methionine and cysteine are vital to biological functions because of the sulfur contained in
their R-groups and versatility in macromolecule synthesis. Methionine is well-known for being
the typical initiating amino acid for protein synthesis and has hydrophobic properties when
incorporated into proteins [36]. These hydrophobic properties usually result in methionine
incorporation within the core of proteins. However, certain proteins have surface-exposed
methionine susceptible to oxidation that is associated with age-related disease [30, 37, 38].
S-adenosylmethionine, a methionine metabolism intermediate, is widely-used with functions
in methylation as well as amine, methylene, and sulfur atom donation [30, 39, 40]. Methionine
is especially important for poultry production as birds have exceedingly high sulfur amino
acid requirements, and low methionine levels can negatively aect growth rate, carcass yield,
fat content, and disease immunity [4143]. Cysteine’s ability to form disulde bonds makes
it incredibly important to tertiary protein structure and can occur with and without enzyme
interactions [30, 44]. Cysteine is involved with keratin and feather production in poultry and
deciencies have been correlated to poor breast muscle development [45, 46]. Swine also need
higher amounts of cysteine as they age to compensate for body maintenance [29, 47].
5. Breeding eorts
Soybean has an extensive cultivated history dating back thousands of years to its country
of origin, China. Glycine max, the contemporary species of soybean, was domesticated from
the wild species Glycine soja and has been continually been improved through selective and
molecular breeding [4850]. Once harvesting traits such as seed shaer and lodging were
improved in the late 1930s to make soybean a competitive row crop, other cultivar improve-
ments became a valuable research goal [49]. Current breeding programs tend to focus on traits
such as yield, disease resistance, abiotic stress tolerance, and seed composition. Seed compo-
sition improvements include protein and oil content, fay acid levels, anti-nutritional factors,
isoavones, and amino acids proles. Before 1972, there had been zero reported research
for improvement of soybean amino acid proles, rather with emphasis on overall protein
content [51]. Modern breeders are also inclined to concentrate eorts on protein content and
consider amino acid levels an afterthought [52]. TN04-5321 is the only released germplasm
in the United States that maintains yield and protein content while improving amino acid
balance by increasing methionine and cysteine to levels recommended livestock needs [53].
The major soybean storage proteins are 11S (glycinin) and 7S (conglycinin) and provide the
bulk of amino acids with limited non-proteinogenic amino acids in seed [5456]. By increasing
11S and 7S quantity, more protein can ultimately be present in food and feed. Overemphasis on
crude protein content can have negative ramications on overall protein quality, specically
Soybean for Human Consumption and Animal Feed4
decient amino acids. While an increase in protein content would theoretically entail an
increase in amino acids including methionine and cysteine [57], the opposite eect has been
more notable [58, 59]. Molecular breeding techniques have recently improved the under-
standing of amino acid genomic regulation. Multiple quantitative trait loci (QTL) studies have
been performed to identify genomic regions that control amino acids levels in soybean seed
[6064]. A myriad of QTL’s were found to create amino acid phenotypic variation. Individual
amino acids had reoccurring or proximal QTL’s discovered such as Sa 518 [60], ss107913002
[61], and BARC-048619 [62] for glycine and threonine. QTL’s for methionine and cysteine
were also discovered which could lead to valuable improvements for soybean livestock feed
[6064]. Other genomic studies such as genome-wide association studies (GWAS) and genetic
diversity analyses would further improve genetic understanding.
6. Genetic engineering
Genetic engineering experiments such as genetically modied organisms (GMOs) and gene
editing are also promising avenues for improving amino acid proles of soybeans. Compared
to conventionally bred varieties, transgenic soybeans face additional adversity from registra-
tion requirements and public opinion. Transgenic eorts generally have one of three targets:
magnifying biosynthesis genes, adjusting biosynthesis regulation, and modifying storage
proteins. The earliest example would be a Brazil nut gene transfer in 1992. This successfully
increased protein content and methionine biosynthesis, however a major food allergen was
also transferred making commercialization impossible [65]. Expressing zein proteins from
corn has also been shown to increase sulfur-containing amino acids levels in soybean [66, 67].
Altering biosynthesis feedback regulation amplied both non-proteinogenic and proteogenic
lysine by circumventing normal enzymatic pathways [68]. Tryptophan in soybean also exhib-
ited increased non-proteinogenic levels when a feedback-insensitive enzyme was transferred
[25]. While soybean is not decient in lysine or tryptophan, corn is decient in both. By increas-
ing lysine and tryptophan concentrations, soybean becomes an even more useful feed additive
to corn rations. Even with limited research on modifying overall amino acids proles in soy-
beans, modifying 11S and 7S storage proteins ratios [69] or silencing their expression entirely
[70] has displayed increased amino acids levels. Similarly, a study using irradiated mutant soy-
beans lacking storage proteins as breeding parents demonstrated increased non-proteinogenic
amino acids contents [54]. In addition, further research should be conducted to determine the
bioavailability and digestibility of increased non-proteinogenic amino acids in soybean.
7. Agronomic relations
Amino acids concentrations in soybean are not only aected by their genetic potential.
Agronomic properties greatly impact the nal levels of amino acids. Agronomy encompasses
all aspects of crop production including environmental eects, climatic variables, and abiotic
factors. Perhaps the most considered agronomic factor is soil nutrient availability. Insucient
Soybean Amino Acids in Health, Genetics, and Evaluation 5
soil nutrient levels of nitrogen, potassium, phosphorous, sulfur, calcium, and magnesium
create poor amino acid proles in soybean plants [71]. Increased phosphorous rates have
been shown to increase the percentage of methionine and tryptophan in seed but had no
eect on protein content percentage [72]. Applications of sulfur, phosphorous, and nitrogen
(individual and combined) produced a variety of dierent methionine and cysteine seed con-
centrations [73]. Sulfur deciencies were also shown to inhibit the production of 11S proteins
while almost eliminating methionine and cysteine in 7S proteins [74]. It is becoming more
popular to also apply biological substances such as amino acids to plants through foliar and
seed application. Amino acid uptake by soybean and wheat have been proven, and improved
soybean growth rates and antioxidant eects have also occurred [75, 76]. Further research
should be conducted to determine if biofortication solutions are possible through amino
acid application.
Amino acid variation has also been shown to occur across environments [24, 59]. Specic
correlations have emerged in response to temperature, solar radiation, and rainfall. One
study shows that increased temperature leads to increased concentrations of all proteino-
genic amino acids [77], while another concludes that only methionine and cysteine increase
alongside temperature [78]. Increased solar radiation and greater available water appeared to
have a negative relationship with amino acid content [77]. These favorable conditions would
increase yield which has been shown to have a negative correlation with overall protein con-
tent [57]. The multitude of agronomic factors that aect amino acid proles in soybean make
it exceedingly important to compensate for variables when researching.
8. Processing impacts
The diversity in food, feed, and industrial used for soybean require the whole seed or seed
components to be processed. Processing can aect the nutritional value of soybean protein
and presence of amino acids in food and feed. Processing procedures can either separate seed
components for dierent purposes or convert the entire seed into a product (usually human
food). Some human soy foods such as edamame and soybean sprouts need lile to no process-
ing. Others including soymilk, tofu, nao, and soy sauce involve more processing. Soymilk
and tofu processing are interconnected. Soymilk is a water-extract of whole or crushed soy-
beans that is coagulated and pressed into tofu [48]. While not all seed proteins convert into
protein in tofu, 11S/7S storage protein ratios have been shown to be both positively and nega-
tively correlated with tofu hardness [79, 80]. Nao is a soy food created by fermenting whole
soybeans with Bacillus subtilis. Fermentation time aects nal amino acid concentrations, and
proper fermentation length could potentially increase nutritional values [81]. Soy sauce is
produced by traditional and commercial methods, but both are based around whole seed or
meal fermentation with Aspergillus sp. However, commercial methods have a lower amino
acid to nitrogen ratio [48].
Soybean meal processing also impacts the level of amino acids in livestock feed. The rst step
in soybean meal processing is essentially separating protein from oil. A variety of methods
Soybean for Human Consumption and Animal Feed6
exist including solvent extraction, screw pressing, and extruding [48, 82, 83]. All three pro-
cesses have three nal products: oil, meal (usually toasted to lessen anti-nutritional factors),
and hulls. Over processing of solvent extracted soymeal has been shown to decrease lysine,
cysteine, and arginine levels [84, 85]. Protein solubility and dispersibility measurements may
be a useful indicator of over processing [86, 87]. Soybean hulls are sometimes added to live-
stock feed for additional ber, however an increase in hull/meal ratios decrease the digest-
ibility of amino acids [88]. While soybean is renowned for its protein and amino acid content,
actual nutritional values can be decreased through certain processing methods.
9. Evaluation methods
All previously mentioned aspects of soybean production in regard to amino acid levels and
human and animal nutrition depend on a single common denominator: amino acid quanti-
cation. Amino acids must be reliably, eectively, and accurately identied, measured and
evaluated. A Google Scholar search of “amino acid analysis” will display over 1 million results.
Several reviews have been published regarding the development of amino acid analysis [8991].
In general, contemporary analysis of amino acids from any source will be performed by chroma-
tography or near-infrared reectance spectroscopy. Chromatography is the common method
with specic techniques including ion exchange chromatography (IEC), high-performance
liquid chromatography (HPLC), and gas chromatography (GC). HPLC is the more validated
method for soybean amino acid analysis. It is more ecient than IEC, and it does not require the
transformation into volatiles like GC [9194]. Near-infrared reectance spectroscopy (NIRS) is a
more recent addition to amino acid analysis, and it has the potential to drastically improve the
eciency in soybean feed evaluation [19]. The inability to actually measure amino acid levels is
main hindrance for NIRS amino acid analysis. NIRS methods must be developed from a calibra-
tion set of raw data (often from HPLC) [9597]. Nonetheless, eciency improvements should
persuade researchers to continually explore future NIRS amino acid analysis applications.
10. Conclusion
Soybean is a valuable source of protein and amino acids for humans and livestock. Soybean’s
well-balanced amino acid prole provides all essential amino acids as well as most nones-
sential. However, there is much room for nutritional improvement. Proteinogenic sulfur-
containing amino acids, methionine and cysteine, are decient in soybean and are especially
needed in livestock rations. Increased levels of these amino acids would augment soybean
meal value and lessen the need for synthetic amino acid supplements. Breeding eorts have
made lile progress in adjusting amino acid proles thus far, however signicant develop-
ments in understanding genomic control regions promise future success. Genetic engineering
eorts have shown promising amino acid improvements, but regulations and public opinion
made commercialization dicult. New gene-editing technology could be the key to unlock-
ing true nutritional improvement.
Soybean Amino Acids in Health, Genetics, and Evaluation 7
Agronomic properties and processing methods both impact the nal quantities of amino acids
available to humans and livestock. Understanding these impacts are essential to improve the
nutritional quality of soybeans. Amino acid evaluation through HPLC provides reliable and
ecient quantication, yet even quicker measurements are possible through NIRS. As the
world’s population continues to grow, soybeans will be essential to both human and livestock
for amino acid requirements. Wholesome approaches that understand the complexities of
amino acids in soybean will be required to maximize overall success and feed the world with
balance soy proteins.
The authors would like to acknowledge Virginia Polytechnic Institute and State University’s
Open Access Subvention Fund for funding the publishing fee.
Conict of interest
The authors declare there is no conict of interest.
Author details
William Monte Singer1*, Bo Zhang1, M.A. Rouf Mian2 and Haibo Huang3
*Address all correspondence to:
1 School of Plant and Environmental Sciences, Virginia Polytechnic and State Institution,
Blacksburg, Virginia, USA
2 United States Department of Agriculture, Agricultural Research Service, Raleigh,
North Carolina
3 Department of Food Science and Technology, Virginia Polytechnic Institute and State
University, Blacksburg, Virginia, USA
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Soybean Amino Acids in Health, Genetics, and Evaluation 15
... The "beany taste" of soy milk has been considered to be a major hurdle of soy milk promotion (Berk, 1992). Soy protein allergy is another hurdle despite of high quality protein with nine essential amino acids (Cordle, 2004;Singer, Zhang, Mian, & Huang, 2019). Besides the preference of soy milk to cow's milk in Asian countries, soybean is in high demand in Asian countries as a common ingredient in their cuisines. ...
Soybean is a food crop in high demand in Northeast Asia. Besides protein and oil, soybean is also a rich source of health-beneficial secondary metabolites such as flavonoids, terpenes, and alkaloids. The long history of soybean domestication resulted in a rich collection of soybean germplasms, which could be generally categorized as wild, landrace, and cultivated soybeans. Previous research has shown that soybean seeds from diverse genetic backgrounds exhibited different metabolite profiles. Germplasms originating from different geographical regions, i.e., at different latitudes and longitudes, probably experienced different selective pressures and evolved different secondary metabolite profiles. Domestication has generally led to a reduction in secondary metabolite contents in seeds since many of these compounds are related to the bitter taste or other agronomic traits that may hinder the ease of farming and harvest. These selection forces have possibly rendered the different flavors of soybean germplasms. Due to the popularity of soy food products, the post-domestication selection of soybean based on flavor is a common phenomenon. In Northeast Asian countries, soy foods such as soy milk, tofu, and fermented soy products are popular. Based on the consumer preference for the flavors of these products, soybean germplasms with different metabolite profiles are selected for different commercial uses. However, the breeding of soybeans for maximizing health benefits and for the preferred flavors of food products may create contradictions. Industrial methods to remove undesirable flavors and molecular breeding to produce cultivars with desired metabolite profiles may be the solution.
... Many components in the mixture are regulated by the stationary phase, forcing them to move at a slower rate than the mobile phase. The relevance of component interactions with the moving or stationary phases controls component mobility in the mobile phase [23]. ...
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The article review discusses a variety of methods for determining amino acid concentrations. The process used to assess the amino acid composition or content of proteins, peptides, and other pharmacological preparations is known as amino acid analysis. Proteins and peptides are macromolecules made up of linear polymers of covalently bound amino acid residues. The qualities of a protein or peptide are determined by the sequence of amino acids in the molecule. On the basis ofrecent publications, this review discusses recent methods developments in amino acids analytics. It aids in the updating and systematisation of knowledge in this field. The advancement of analytical methods is highlighted, along with the benefits and limitations of the numerous procedures used for the manufacture, separation, and determination of amino acids. The preparation requirements for methods analysis vary depending on the type of material. As a result, the focus of the review has beenon detection and estimation of amino acids, including: ninhydrin method, ion exchange chromatography, liquid chromatography, gas chromatography and other methods
... Edamame is source of carbohydrate, protein, fiber, bioactive peptides, omega-3 fatty acids, minerals (potassium, calcium, phosphorous, magnesium, iron), folic acid and phytochemicals components, namely isoflavone (0.1-3.0%), sterols (0.23-0.46%), and saponin (0.17-6.16%). Edamame is only one legume that contains essensial amino acids such as phenylalanine, isoleucine, lysine, threonine, tyrosine, valine, tryptophan, methionine, and cysteine [1,2]. ...
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Edamame soybeans have excellent prospects for development in the lowlands. In order to grow well, edamame soybeans need liquid organic fertilizer as a nutrient supply and proper spacing. The objective of the research was to evaluate the effect of spacing treatment and application of liquid organic fertilizer (LOF) on soybean edamame growth and production. A field research was conducted in Medan from September until December 2019, using a factorial randomized block design with two factors and three replications. The first factor is spacing treatment of edamame, namely 40cmx20cm; 30cm x 20 cm and 20cm x 20cm. The second factor is LOF application consisting of 40; 60 and 80 mL/L of water. Research result showed that spacing of 30cm x 20cm treatment increased the number of productive branches. LOF treatment of 40mL/L of water increased the dry weight of 100 seeds. The interaction between plant spacing and LOF application had no significant effect on all observed variables.
... Soybean supplies the majority of the protein content that humans consume and is a leading source of high-quality and essential amino acids derived from plants [138]. Although there have been numerous studies discussing the technical use of soy protein since the 1950s, the consumption of the protein has yet to draw level with its production [139]. ...
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In addition to providing nutrients, food can help prevent and treat certain diseases. In particular, research on soy products has increased dramatically following their emergence as functional foods capable of improving blood circulation and intestinal regulation. In addition to their nutritional value, soybeans contain specific phytochemical substances that promote health and are a source of dietary fiber, phospholipids, isoflavones (e.g., genistein and daidzein), phenolic acids, saponins, and phytic acid, while serving as a trypsin inhibitor. These individual substances have demonstrated effectiveness in preventing chronic diseases, such as arteriosclerosis, cardiac diseases, diabetes, and senile dementia, as well as in treating cancer and suppressing osteoporosis. Furthermore, soybean can affect fibrinolytic activity, control blood pressure, and improve lipid metabolism, while eliciting antimutagenic, anticarcinogenic, and antibacterial effects. In this review, rather than to improve on the established studies on the reported nutritional qualities of soybeans, we intend to examine the physiological activities of soybeans that have recently been studied and confirm their potential as a high-functional, well-being food.
... In most poultry and swine diets soybean meal provides 80% of the dietary amino acids. Ideal protein describes the profile of dietary amino acids that are in perfect harmony with the animal's nutritional requirements (Dei, 2011;Singer et al., 2019). The determined amino acid profiles of soybean meal, soybean cake and sunflower meals are presented in Table 2. ...
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A global increase in the demand for livestock products suggests that there will be a consequent rise in demand for feed, not only of cereals but of other feeds and particularly proteins. In the present study, oil industry by-products such as soybean meal, soybean cake and sunflower meal were analysed as sources of amino acids in animal nutrition. From among oilseed by-products, the soybean meal content the most of crude protein up to 44% and the best of amino acid composition, while content of crude cellulose (about 6%) is lower in comparison to other oilseed meals. The results showed that the total amino acids in the examined samples ranged from 31.87 to 41.01%, and the total essential and nonessential amino acids varied from 13.41 to 17.38% and from 18.46 to 23.76%, respectively. Generally, the protein contained in soybean meal and cake was rich in essential amino acids. However, because of the lowest amino acid score, methionine was considered as a limiting amino acid in both soybean by-products. On the other hand, soya's meal contained higher level of lysine than other protein-based vegetable alternative to soya like sunflower meals examined in this study. Glutamic acid, aspartic acid, leucine and valine were the most abundant amino acids in all tested by-products of the oil industry. Therefore, partial substitution of protein sources in feeds with proteins from the oil industry by-products may improve feed quality.
... The author concluded that there was no significant correlation between the tofu hardness and the 11S:7S ratio. Both positive and negative correlations between the 11S:7S storage protein ratios and tofu hardness were reported by different group of researchers (Singer, Zhang, Mian, & Huang, 2019). ...
Tofu is a traditional product made mainly from soybeans, which has become globally popular because of its inclusion in vegetarian, vegan, and hypocaloric diets. However, with both commercial production of tofu and scientific research, it remains a challenge to produce tofu with high quality, high nutrition, and excellent flavor. This is because tofu production involves multiple complicated steps, such as soybean selection, utilization of appropriate coagulants, and tofu packaging. To make high‐quality tofu product, it is important to systematically understand critical factors that influence tofu quality. This article reviews the current research status of tofu production. The diversity of soybean seeds (the raw material), protein composition, structural properties, and nutritional values are reviewed. Then, selection of tofu coagulants is reviewed to provide insights on its role in tofu quality, where the focus is on the usage of mix coagulants and recent developments with new coagulants. Moreover, a comprehensive summary is provided on recent development in making high‐fiber tofu using Okara (the major by‐product during tofu production), which has a number of potential applications in the food industry. To help encourage automatic, environmental friendly, and high‐efficient tofu production, new developments and applications in production technology, such as ultrasound and high‐pressure process, are reviewed. Tofu packaging, including packaging materials and techniques, is evaluated as it has been found to have a positive impact on extending the shelf life and improving the quality of tofu products. Finally, the future research directions and potential areas for new developments are discussed.
... Soy milk is also well known for its high amino acid quality (Abbaspour et al., 2019). The well-balanced amino acid profile of soy milk protein in which it contains all nine essential amino acids makes the milk a significant nutritional foundation to the dietary needs of humans (Singer et al., 2019). While raw soybean protein has poor digestibility due to the presence of endogenous inhibitors of the protein digestive enzymes, protein in soy milk, on the other hand, can be easily digested by the body as the heat treatment destroys most of the inhibitors (Friedman and Brandon, 2001). ...
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Coconut milk is widely used in Malaysia as one of the essential ingredients in preparing traditional baked cake or ‘kuih bakar’. Increased demand for coconut milk affects its availability and cost. Thus, it is important to study a possible alternative ingredient to ensure the continuity of this traditional dessert. This project aimed to determine the physicochemical and sensory properties of ‘kuih bakar’ produced with coconut milk and soy milk. In the present study, ‘kuih bakar’ was prepared with fresh coconut milk (FCM) (positive control), fresh soy milk (FSM), commercial coconut milk (CCM), commercial soy milk (CSM), and without milk (negative control). Proximate analysis showed that substitution of coconut milk with soy milk reduced the fat and increased the protein content of ‘kuih bakar’ significantly (p < 0.05). However, the substitution of coconut milk did not show a significant effect (p > 0.05) on the colour properties and water activity of the sample. There were significant differences (p < 0.05) in scores during sensory evaluation between the samples but the ‘kuih bakar’ produced with FSM showed no significant difference (p < 0.05) as compared to FCM and CCM. This study demonstrated that physicochemical and sensory attributes of traditional ‘kuih bakar’ can be maintained by using FSM as a substitution of the traditional coconut milk used in producing ‘kuih bakar’.
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Soybean (Glycine max) is a major plant protein source and oilseed crop. However, plant-parasitic nematodes (PPNs) affect its annual yield. In the current study, in order to better understand the regulation of defense mechanism against PPNs in soybean, we investigated the role of long non-coding RNAs (lncRNAs) in response to two nematode species, Heterodera glycines (SCN: soybean cyst nematode) and Rotylenchulus reniformis (reniform). To this end, two publicly available RNA-seq data sets (SCN data set and RAD: reniform-associated data set) were employed to discover the lncRNAome profile of soybean under SCN and reniform infection, respectively. Upon identification of unannotated transcripts in these data sets, a seven-step pipeline was utilized to sieve these transcripts, which ended up in 384 and 283 potential lncRNAs in SCN data set and RAD, respectively. These transcripts were then used to predict cis and trans nematode-related targets in soybean genome. Computational prediction of target genes function, some of which were also among differentially expressed genes, revealed the involvement of putative nematode-responsive genes as well as enrichment of multiple stress responses in both data sets. Finally, 15 and six lncRNAs were proposed to be involved in microRNA-mediated regulation of gene expression in soybean in response to SNC and reniform infection, respectively. Collectively, this study provides a novel insight into the signaling and regulatory network of soybean-pathogen interactions and opens a new window for further research.
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Soybean is important throughout the world due to its high seed protein and oil, while the quality and quantity of seed amino acids need to be improved. To improve the multiple amino acid concentrations in soybean simultaneously, detecting and utilizing the pleiotropic quantitative trait loci (QTL) and related genes become increasingly important. In view of this, a F6:7 recombinant inbred line population was genotyped using 1739 polymorphic SNP and 127 SSR markers in the present study and was phenotyped for seventeen types of amino acids simultaneously. In total, twelve co-located or overlapped pleiotropic additive QTL clusters, which explained 2.38–16.79% of the amino acid variation, were identified. Of them, one novel pleiotropic QTL cluster with a phenotypic variation explained ranging from 8.84 to 16.79% for ten kinds of amino acid contents (glycine, alanine, isoleucine, leucine, valine, methionine, aspartic acid, glutamic acid, lysine and phenylalanine), was located at the same position on linkage group D2, and the confidence interval was only 0.8 cM. Moreover, the individuals in this family-based population (345 lines) and another cultivar-based population (254 varieties) with different genotypes at the common flanking markers for this QTL cluster showed significantly different amino acid contents, which further validated the QTL mapping results. Additionally, some candidate genes that might participate in the amino acid biosynthesis process were found in these pleiotropic QTL regions. Thus, novel pleiotropic QTL clusters could be applied in marker-assisted selection breeding or map-based candidate gene cloning in soybean for multiple amino acid genetic improvements in seed in the future.
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In recent years, the application of natural substances on crops has been intensified in order to increase the resistance and yield of the soybean crop. Among these products are included plant biostimulants that may contain algae extracts, amino acids, and plant regulators in their composition. However, there is little information on the isolated effect of each of these constituents. The objective of this research was to evaluate the effect of the application of isolated amino acids on the antioxidant metabolism of the soybean crop. Experiments were carried out in a greenhouse and in the field with the application of the amino acids glutamate, phenylalanine, cysteine, glycine in seed treatment, and foliar application at V4 growth stage. Antioxidant metabolism constituents evaluated were superoxide dismutase, catalase, peroxidase, hydrogen peroxide content, proline, and lipid peroxidation. In addition, resistance enzymes as polyphenol oxidase and phenylalanine ammonia-lyase (PAL) were evaluated. In both experiments, the use of cysteine, only in seed treatment and in both seed treatment and foliar application increased the activity of the enzyme PAL and catalase. Also in both experiments, the use of phenylalanine increased the activity of the enzyme PAL when the application was carried out as foliar application or both in seed treatment and foliar application. In the field experiment, the application of glutamate led to an increase in the activity of the catalase and PAL enzymes for seed treatment and foliar application. The use of the set of amino acids was only efficient in foliar application, which led to a greater activity of the enzymes peroxidase, PAL, and polyphenol oxidase. The other enzymes as well as lipid peroxidation and hydrogen peroxide presented different results according to the experiment. Therefore, glutamate, cysteine, phenylalanine, and glycine can act as signaling amino acids in soybean plants, since small doses are enough to increase the activity of the antioxidant enzymes.
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Amino acid NIR calibrations were developed in our Physical Chemistry of Foods Laboratory of the University of Illinois at Urbana for three selected amino acid groups that include essential amino acids for identified soybean accessions. Conventional “wet chemistry” analytical methods are time-consuming and costly. As a result, soybean breeders and researchers have an imperative need to utilize faster and less expensive methods. NIR Spectroscopy is a rapid and inexpensive method for composition analysis for academia and industry. Recent advancements in instrumentation design, such as the application of the Diode Array (DA) technique and the Fourier Transform (FT) IR and NIR techniques, have significantly improved overall instrument performance and advancement in the field of grain analysis.Novel results are presented for amino acid calibrations for US soybean accessions relevant to the food and agricultural industry.
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Soil-borne amino acids may constitute a source of nitrogen (N) for plants in various terrestrial ecosystems but their importance for total N nutrition is unclear, particularly in nutrient-rich arable soils. One reason for this uncertainty is lack of information on how the absorption of amino acids by plant roots is affected by the simultaneous presence of inorganic N forms. The objective of the present study was to study absorption of glycine (Gly) and glutamine (Gln) by wheat roots and their interactions with nitrate (NO<sub>3</sub><sup>−</sup>) and ammonium (NH<sub>4</sub><sup>+</sup>) during uptake. The underlying hypothesis was that amino acids, when present in nutrient solution together with inorganic N, may lead to down-regulation of the inorganic N uptake, thereby resulting in similar total N uptake rates. Amino acids were enriched with double-labelled <sup>15</sup>N and <sup>13</sup>C, while NO<sub>3</sub><sup>−</sup> and NH<sub>4</sub><sup>+</sup> acquisition was determined by their rate of removal from the nutrient solution surrounding the roots. The uptake rates of NO<sub>3</sub><sup>−</sup> and NH<sub>4</sub><sup>+</sup> did not differ from each other and were generally about twice as high as the uptake rate of organic N when the different N forms were supplied separately in concentrations of 2 mM. Nevertheless, replacement of 50% of the inorganic N with organic N was able to restore the N uptake to the same level as that in the presence of only inorganic N. Co-provision of NO<sub>3</sub><sup>−</sup> did not affect glycine uptake, while the presence of glycine down-regulated NO<sub>3</sub><sup>−</sup> uptake. The ratio between <sup>13</sup>C and <sup>15</sup>N were lower in shoots than in roots and also lower than the theoretical values, reflecting higher C losses via respiratory processes compared to N losses. It is concluded that organic N can constitute a significant N-source for wheat plants and that there is an interaction between the uptake of inorganic and organic N.
Soybean [Glycine max (L.) Merr.] is the primary source of meal used in animal feed in the U.S. However, few studies have been conducted to evaluate genomic regions controlling amino acid composition is soybean. Designing soybean seed compositions that will benefit animal production is essential. The objective of this study was to identify genomic regions controlling essential and non-essential amino acid composition in soybean seed proteins. To achieve this objective, 282 F5:9 recombinant inbred lines (RILs) developed from a cross of Essex × Williams 82 were used. Ground soybean seed samples were analyzed for amino acids and statistically significant differences (p < 0.05) were found among genotypes in the population for all amino acid concentrations. The Universal Soy Linkage Panel (USLP) 1.0 of 1,536 single nucleotide polymorphism (SNP) DNA markers were used to genotype the 282 RILs and identify 480 useful genetic markers. The software R/qtl was used to identify candidate quantitative trait loci (QTL), which were validated using R/MQM. A total of ten QTL were detected on chromosomes 5, 7, 9, 10, 13 and 20 that explained 5 to 14% of the total phenotypic variation for a particular amino acid. Using SNPs from the USLP 1.0 to detect QTL for amino acids in soybean provides additional information to select genotypes with enhanced amino acid profiles that will benefit animal production.
The methionine-rich seed storage proteins of maize have been expressed in transgenic plants as a means to improve the overall sulfur amino acid content of seed. Previous attempts to increase the sulfur amino acid content of soybean seeds by this approach has met with limited success. It has been shown co-expression of different class of zeins can result in their stable accumulation in transgenic plants. In this study, conventional crosses between transgenic plants individually expressing 11, 18 kDa δ-zeins and 27 kDa γ-zein were made to obtain plants that simultaneously express both the δ-zein and γ-zein. Transmission electron microscopic observation of thin-sections of transgenic soybean seeds revealed that the zeins accumulated in ER-derived protein bodies (PBs) which were found sparsely scattered in cytoplasm. The size of these PBs varied from 0.2 to 0.6 μm in soybean plants individually expressing 11, 18 kDa δ-zeins and 27 kDa γ-zein. In contrast, soybeans co-expressing the 18 kDa δ-zein and 27 kDa γ-zein the PBs was 3–4 times larger. Electron microscopic observation also revealed the sequestration of PBs inside the vacuoles where they could be subjected to degradation by vacuolar proteases. Amino acid analysis of transgenic soybean individually expressing 11, 18 kDa δ-zeins and 27 kDa γ-zein revealed only a minimal increase in the overall methionine content compared to the wild-type. In contrast, plants co-expressing 18 kDa δ-zein and 27 kDa γ-zein showed a significant increase (27%) in the methionine content compared to the control seeds.
Soybean [Glycine max (L.) Merr.] produces a high-quality protein that provides an appropriate balance of amino acids for monogastric animals. It has been reported that the relative abundance of some essential amino acids may be reduced in soybean with high protein concentration. A dilution of essential amino acids in soybean protein would lead to a reduction in the value of that protein to the end user, and undefined variation in amino acid balance of soybean would lead to poorly balanced animal rations. The objective of this work was to determine whether amino acid balance is affected by seed protein concentration and to characterize any putative changes in the relative abundance of each amino acid across a range of soybean protein concentrations. We created a wide range of protein concentrations in soybean seed by imposing managed stress treatments previously shown to lower or raise protein concentration. We found that the amino acid composition of soybean protein was affected by protein concentration. The relative abundance of amino acids that are often limiting for animal growth, such as lysine, methionine, cysteine, tryptophan, and threo-nine, were reduced with increasing seed protein concentrations, whereas arginine and glutamic acid were increased. However, treatments used in this study uncovered a potential role for the availability and source of reduced C and N to impact the relative abundance of each amino acid independently, highlighting the complexity of this interrelationship. © Crop Science Society of America | 5585 Guilford Rd., Madison, WI 53711 USA All rights reserved.