Food Commodities Soybeans

Soybeans account for about 50% of the global oilseed production

Temperate climates are better suited for soybean production

• Prefers soil pH ranging from 6-6.5
• Alkaline soils; may be necessary to adjust pH with acid treatment (usually acetic acid)

Due primarily to the presence of CaCO3

Treatment with acid will use up the CaCO3 and when the latter is depleted, the pH of the soil falls until the desired level

Acidic pH due to emissions producing oxides of C, S, and N into the atmosphere that become part of rain

Spherical to elongated and flat

The beans used for oil production tend to be yellowish in color, small in size and spherical in shape

The beans used as vegetables tend to be larger in size, elongated in shape and of varied colours (yellow, green, brown, black)

• Mature seeds are left on the plants to dry out until a moisture content of 12-13% is reached.
• 12-13% moisture content is the best or storage stability of the beans as well as the handling characteristics

Makes beans susceptible to mould and fungal growth

Moisture content <12% makes beans very brittle and break easily

Composition of soybeans is expressed in moisture-free basis because the seeds are practically dried when they are picked and stored

Has 2 seeds leafs covered by an outer layer known as the testa

Approximately 4.5 tons of soybean oil meals with a protein content of about 44%

Mostly due to the sharp increase in the US production between 1950 and 1970, and to the introduction of the soybean to Brazilian agriculture in the 1960s

Late spring to early summer

early-to-mid autumn

the cotyledon represents ~90% of the seed weight and contains practically all the oil and protein in its cells

In the cotyledon

Consists of the seed coat (testa), 2 cotyledons, the radicle and plumule

Obtained by solvent (hexane) extraction, used as cooking oil, but also used in the chemical industry as starting material for bio-diesel, inks, plasticizers, crayons, paints, and even candles

Ground flakes after oil extraction, used for feed (cattle, swine, poultry, and fish)

Refers to defatted soybeans where special care was taken during solvent removal in order to minimize denaturation of the protein (minimum 50% protein content), starting material for protein enriched soy products

SPC has 65% to 85% protein content

Usually manufactured by using alcohol to remove the soluble carbohydrates from the de-oiled soy flakes, resulting in a protein with low solubility, good water holding capacity, but incapable to forming gels or emulsifying fat.  Traditional alcohol-washed soy concentrates are used

• disaccharide of glucose and fructose
• glycosidic bond
• The glycosidic bond for the sucrose is sometimes referred to as an a-b-1-2 bond, because there's an alpha-OH from the glucose bonding to a beta-OH from the fructose, and we're going from the #1 carbon on the glucose to the #2 carbon on the fructose
• not a reducing sugar

• trisaccharide of galactose, fructose, and glucose
• galactose and glucose are linked by alpha-1,6-glycosidic bond and glucose is linked to fructose by an alpha,beta-1,2-glycosidic bond
• not a reducing sugar

• tetrasaccharide
• two α-D-galactose units, one α-D-glucose unit, and one β-D-fructose unit sequentially linked as gal(α1→6)gal(α1→6)glc(α1↔2β)fru
• reducing sugar (=has an aldehyde group or is capable of forming one through isomerism, allowing the sugar to act as a reducing agent)

• Storage (80%)
• Bioactive (20%)

High solubility in salt solutions but dissolves to some extent in H2O

Proteins very soluble at extreme pHs but with limited solubility at pH 4.2-4.5

Based on size (weight)

• Proteins with sizes ranging from 8-20 kDa
• Alpha conglycinin (storage protein) and soybean trypsin inhibitor (bioactive protein)
• Alpha-conglycinin elicits allergic type reactions in some individuals

• Molecular weights ranging from 120-150 kDa
• main proteins include beta and gamma- conglycinins (storage proteins) and enzymes like LOX, amylases, cysteine, proteases and urease

• 320-350 kDa
• Glycinin

• 7S and 11S are the most abundant and account for about 70% of the soy proteins
• Ratios in which the 7S and 11S occur (0.5:3.0) are distinct features of different varieties of soybeans and is used as a basis for classification

80% storage proteins serve as nutrient/energy source

Soybean protein of comparable nutritive value as egg or meat proteins

Lipoxygenase

Can cause breakdown of soybean lipids to form carbonyl compounds that impart objectionable 'beany' flavour or taste to soy products so the need for LOX to be removed or inactivated

LOX breaks down carotenoid pigments and this feature is exploited in decolourizing of wheat flour

Breaks down proteins (uric acid) to liberate NH3, which can impart objectionable flavour to soybeans and its products

• Urease is heat stable and its inactivation is used as a measure of the effectiveness of heat treatment for soybeans
• If heat treatment is not adequate, enzymes like LOX and urease can survive and cause objectionable flavour

• Lytic enzymes
• Amylases
• Proteases
• Other biological components

Break down cell walls to permit germination

• A proteolytic enzyme found only in animals
• Causes pancreas to overproduce trypsins
• (Why? Trypsin is an enzyme produced by your pancreas used in digesting protein, and is critical for antibody production. An inhibitor is something that disables. Think of it like having one foot on the gas and another on the brake of your automobile at the same time. Your car’s engine would blow-up. So a trypsin inhibitor will irritate your pancreas, stressing it to produce hormones when it can’t, leading to decreased oxygenation from the irritation. Soy prevents the protein you eat from being fully utilized and digested. Your immune system can’t get fueled with proper antibodies and lymphocytes — a double whammy. Therefore, soy is cancer-causing to your pancreas and cancer of the pancreas is typically a death sentence.)

• Protein molecules with strong adhesive properties
• They are known to cause agglutination of blood cells

They can bind to the surfaces of the intestine at the distal end and interfere with intestinal metabolsim

• Both SBTI and lectins are denatured by the heat treatments normally applied to soybeans
• Thus, their harmful effects are curtailed by heat treatment

High pressure treatment can also denature lectins, however this technique is not used commercially to denature lectins because of the expense

• Non nutrients
• Some elicit hormonal effects in mammals (including humans) 
• Some elicit anti-oxidant and/or anti-cancer effects

• Not efficient
• Costly and low yield

Solvent extraction

• Cleaning
• De-hulling
• Flaking
• Solvent extraction
• Purification
• Bleaching

• Undesirable components like twigs, stones, empty or free hulls are removed
• Magnetic separation to remove small pieces o metals that may become part of the beans during harvesting

• Wash to remove dirt
• Dry

Entails cracking beans open to remove the seeds and exclude the hulls

• Involves heating the seeds in water to facilitate slicing into flakes
• This is important to increase surface area for the extraction step with the solvents

Hexanes

Soyflakes are treated with hexanes by soxhlet extraction- to recover oil in the solvent phase while the solid residue (mainly proteins and carbohydrates) are retained

• Filtration to remove undesirable components
• Filtration to remove insoluble material
• Degumming by hydrating phosphatids dissolved in oil with water and with acid (phosphoric acid)
• The phosphatids hydrate, expand and agglomerate to form large peptides that are removed in a separation step using separations
• Alkaline treatment to form soaps with the FFA
• Water wash to remove soaps
• Vacuum drying to remove moisture

• Alkaline treatment to form soaps with FFA
• Water wash to remove soaps

• Hydrating phosphatids dissolved in oil with water and with acid (phosphoric acid) 
• The phosphatids hydrate, expand, and agglomerate to form large peptides that are removed in a separation step using separations

Steam stripping or vacuum, evaporation of oil to exclude volatiles

• To remove coloured pigments that may be present in the oil
• Usually involves heat treatment to degrade the pigments which are then adsorbed onto adsorbents like activated charcoal or bentonite

• May be treated further to remove waxes and triacylglycerides.  These latter components have high melting points, so by slowly cooling the purified oil, we can get them to crystallize out and separate
• This process is known as WINTERIZING or WINTERIZATION

• Hardens the oils to various degrees
• Hydrogenation stabilizes the oils (via reduction in degree of unsaturation in the oils)

• Results in reduced unsaturation and formation of cis-and trans- isomers
• Trans fats are considered not desirable for health

• High in PUFAs 587-60%
• MUFA- 23-26%
• SFA- 16%

• Linoleic acid (50%)
• Linolenic acid (7-10%)

Oleic acid (23%)

• Palmitic acid (10%)
• Stearic acid (4%)

This solid residue may be treated to remove solvents (de-solventization) and fed as soy meal to animals (cattle, fish, poultry, etc)

Made from the whole non de-fatted beans

• Produced with low-mild heat treatment so it retains enzymes like LOX in active forms
• Produced with regular high heat treatment

Produced by washing defatted soy flour with ethanol to remove CHO

• N-fixing capacity through symbiosis with soil bacteria
• It is estimated that up to 50% of the total nitrogen of the plant may be supplied by the nitrogen fixing mechanism

• Sucrose
• Raffinose
• Stachyose
• Cellulose
• b-Glycans
• Pectins
• Gums
• Hemicelluloses

• Evaluated by its chemical score (by comparing its essential amino acid composition to that o a standard reference protein such as whole egg protein
• Chemical score of soybean protein is 70%

Exceptionally rich in lysine and can sere as a valuable supplement to sereal foods where lysine is a limiting factor

By their solubility in various media

4.2-4.6

The bulk of soybean proteins are globulins, characterized by their solubility in salt solutions

Soy protein is heterogeneous, and when centrifuged (at pH 7.6 and 0.5 ionic strength), produce fractions 2S, 7S, 11S, 15S.

Soy proteins are fractionated by ultracentrifugation, gel filtration and electrophoresis

Responsible for oxidative rancidity in soybean oil

• Kunitz inhibitor (20kDa)
• Bowman-Birk inhibitor (80kDa)

When soybean is properly heated

Impair protein digestibility and utilization

• Increase pancreatic secretion and hypertrophy of the pancreas
• Increased secretion of enzymes into the GIT represents an internal loss of protein

Can bind to the surfaces in the distal part of the small intestine to damage small intestine villi and disrupt small intestinal metabolism

Not digestible and produce gas and cause bloating and abdominal discomfort

HPP is capable of altering the molecular structure of antigens (proteins) which are the starting point of food allergies

• Roasted whole soybeans and their flour are used as ingredients in confectionery products and snacks
• The immature whole green soybeans are also consumed as a vegetable

First, because of their high protein content and low starch content, soybeans require much longer cooking than most other beans, generally 5-6 hours without pressure (but only 25-30 minutes at 15 pounds pressure), and even after this they never get as soft as most beans. Also, this long cooking uses lots of fuel, which has always been relatively expensive in densely populated areas. Moreover, the water in China is generally hard (rich in calcium), which further increases the required cooking time. Second, boiled or baked whole soybeans are more difficult to digest than most other soyfoods and than some other dry beans; the oligosaccharides they contain, which are removed in the processing of most soyfoods, can cause flatulence. And third, most East Asian people prefer the flavor and versatility of other soyfoods. (People in countries that have not traditionally consumed soybeans often describe them as having a "beany" flavor). Yet throughout East Asia, whole dry soybeans have long been used in certain dishes at certain times.

Made from powdered roasted soybeans

Principle use of FFSF and grits is in the bakery industry

• Enzyme-active: prepared without heat treatment and used mostly in bakery products (white bread and rolls), mainly for its LOX activity
• Enzyme-inactive: prepared with heat treatment and used in the heavier types of cake batters, such as sponge cakes and pound cakes)

Used as a protein supplement in bread, tortillas, pasta and other cereal products

Bakery products, meat products, and as stabilized dispersions in milk-like beverages and simulated dairy products

• Dry beans are rehydrated by soaking in water overnight (min 3 hrs)
• Beans are then wet milled with water to form a slurry
• The resulting slurry or puree is heated close to boiling for ~15-20 min (to improve nutritional value by heat inactivating soybean trypsin inhibitor, improve its flavour and to sterilize the product)
• The boiled slurry is cooled and filtered to remove the insoluble residue (soy pulp fiber or okara)