Soybean extraction meal [German version]

Table of contents

Product information
  Container transport
  Cargo securing

Risk factors and loss prevention:
Temperature Odor
Humidity/Moisture Contamination
Ventilation Mechanical influences
Biotic activity Toxicity / Hazards to health
Gases Shrinkage/Shortage
Self-heating / Spontaneous combustion Insect infestation / Diseases

Product information

Product name

German Sojabohnen-Extraktionsschrot
English Soybean extraction meal
French Extrait de soja
Spanish Extracto partido de semillas de soja
Scientific Glycina soja and Soja hispida
CN/HS number * 2304 00 00

(* EU Combined Nomenclature/Harmonized System)

Product description

Soybean extraction meal comprises residues arising from oil extraction from soybeans performed using an extraction solvent.

The starting materials for this solvent extraction process are oil seeds with a low oil content or expeller pulp produced by previous cold or hot pressing (Manufacture of vegetable pressing residues). The oil is extracted from the rough-ground product by chemical fat solvents (n-hexane), leaving a residual oil content of only 0.5 – 1.5%. These residues are then known as extraction meal.

After extraction of the fat, the solvent is removed from solvent-damp extraction residues in a toaster (desolventizer) using steam.

The primary advantage of n-hexane as an extraction solvent over other solvents is that it is readily removable from the extracted products; residues should be at most 0.05 – 0.1%. It has the disadvantage, however, of being readily combustible. Toasting of the product at temperatures of 60°C upwards has favorable side-effects:
  1. it leads to the deactivation of microorganisms and enzymes which may have deleterious effects on feedstuffs during storage and transport

  2. toasting converts the vegetable protein into a readily digestible form.

Toasted extraction meal leaves the production plant while still hot and with a variable moisture content. After toasting, the extraction meal is cooled and, since it is in large pieces, it is ground and adjusted to a water content suitable for storage and transport.

It is either held in intermediate storage in silo cells or sent for transport. It is transported as bulk cargo, being seldom handled as bagged goods these days.

Grain size: approx. 40 – 80% of the total volume of a bulk cargo is of a grain size of diameter < 2 mm

Oil content: 0.5 – 1.0% [1]

Quality / Duration of storage

Product intended for shipping must be adequately matured. The time required for maturing is determined by the oil content. On the other hand, however, product from the previous year’s harvest must not be accepted for shipping.

The consignor must provide certificates relating to the moisture and residual oil content and the maturing time of the product. Confirmation or certification should also be obtained that the product is extraction meal.

Soybean extraction meal consists of yellow to medium brown flakes of varying sizes. Upon acceptance of a consignment, dark, brown or reddish discoloration of the goods must be looked for, since this indicates overheating during toasting or excessively long storage.

Intended use

Due to its high protein content, soybean extraction meal constitutes a valuable concentrated feed additive for all kinds of animal. The protein content of soybean extraction meal is among the highest of any feedstuff. It is preferably fed to pigs, dairy cattle and poultry.

Countries of origin

This Table shows only a selection of the most important countries of origin and should not be thought of as exhaustive.

America USA, Brazil

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Extraction meal is mainly transported as bulk cargo. Only exceptionally is the product transported as bagged cargo (in very small quantities).

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Bulk cargo
Symbol, Class 4.1

Spontaneously combustible,
Class 4.2 IMDG Code

Means of transport

Ship, truck, railroad

Container transport

Bulk containers subject to compliance with lower and upper limits for water and oil content and the maturing time of the product and water content of the container floor (see RF Self-heating, possible fire hazard due to solvent residues).

Cargo handling

Do not unload very hot product with hydraulically operated grabs as the hydraulic lines are not capable of withstanding such elevated temperatures. Use only cable-operated grabs for spontaneously heated product.

Stowage factor

1.78 – 1.81 m3/t [1]

Angle of repose

> 35°

Grain size

approx. 40 – 80% of the total volume of a bulk cargo is of a grain size of diameter < 2 mm

Stowage space requirements

Cool, dry. Mechanical ventilation of the stowage spaces must be possible. Do not stow over heated double bottom tanks, close to the engine room bulkhead and pipework which may become hot.



Cargo securing

In the case of maritime transport, the IMO (International Maritime Organization) „Code of Safe Practice for Solid Bulk Cargoes“ must be complied with.

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Risk factors and loss prevention

RF Temperature

Soybean extraction meal requires particular temperature, humidity/moisture and ventilation conditions (SC VII) (storage climate conditions).

Favorable travel temperature: 5 – 25°C [1]

Up to a temperature of 25°C, meal may be loaded irrespective of the external temperature. At elevated external temperatures, the product temperature must be no more than 10% higher than the external temperature. Continuous temperature measurements should be taken during loading of the cargo. In tropical ports, temperatures of 25 – 55°C may occur in the products to be loaded.

The temperature must accordingly also be measured at various depths in the hold during the voyage. If the temperature rises above 55°C and any further increase is observed, countermeasures must be taken, e.g. tight closing of all hatch openings and injection of CO2 or inert gas (see RF Self-heating). Since extraction meal is deoiled by means of solvents, use of CO2 should be maintained until any fire hazard has been overcome and ignition of the solvent vapors by static electricity has been prevented.

The enzymes which initiate and intensify fat degradation and thus the self-heating process reach optimum levels of activity at temperatures of 35 – 40°C, i.e. temperatures which are easily reached within the heaped cargo. The travel temperature should thus be between 5 and 25°C. Temperatures of up to 30°C are also admissible for short periods. However, these conditions are difficult to maintain during an ocean voyage, as a consequence of which very careful attention must be paid to ensuring that the critical water content of the product is not exceeded in order to avoid self-heating to the greatest possible extent.

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RF Humidity/Moisture

Soybean extraction meal requires particular temperature, humidity/moisture and ventilation conditions (SC VII) (storage climate conditions).

Designation Humidity/water content Source
Relative humidity 70% [1]
Water content 5 – 12.5% [1]
Maximum equilibrium moisture content 70% [1]

The meal must be protected from all forms of moisture (seawater, rain and condensation water), since moisture encourages mold, mustiness and self-heating.

Moisture promotes self-heating brought about both by hydrolytic/enzymatic degradation and by microorganisms and may be the result of an excessively high product water content or alternatively of external influences (excessively high relative humidity (critical equilibrium moisture content 75%), water splashes, rain). Soybean extraction meal is also highly susceptible to mold growth due to an excessively high water content.

At a water content of < 5%, there is a risk of oxidative fat cleavage, dust formation/dust explosions and self-heating.

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RF Ventilation

Soybean extraction meal requires particular temperature, humidity/moisture and ventilation conditions (SC VII) (storage climate conditions).

Recommended ventilation conditions: surface ventilation.

Solvent vapors from extraction meal are heavier than air and do not take the form of surface vapors; as a result, they cannot rise upwards and be dissipated by surface ventilation. They may theoretically be eliminated by ventilation only if the temperature of the cargo rises due to self-heating, causing the vapors to rise in the cargo, in which case, however, direct surface ventilation would be inappropriate (see RF Self-heating).

In order to avoid moisture damage on the surface of the cargo (cargo sweat), ventilation must not be performed with cold external air. The ventilation system must then be switched to return air.

No access is permitted to the holds until they have been adequately ventilated and a gas measurement has been carried out. Since the solvent vapors are denser than air, they may have accumulated in the lower parts of the hold.

A certificate stating residual oil content, water content and maturing time should be demanded from the consignor.

If the oxidation processes under way in the hold are vigorous, it is not possible to dissipate the quantity of heat generated by ventilation. This particularly applies if a sub-batch susceptible to oxidation with a low water content is loaded next to a sub-batch with a high moisture content.

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RF Biotic activity

Soybean extraction meal displays 3rd order biotic activity.

It belongs to the class of products in which respiration processes are suspended, but in which biochemical, microbial and other decomposition processes still proceed.

Care of the cargo must be aimed at limiting the autoxidative fat cleavage process and so preventing possible self-heating of the product.

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RF Gases

An increase in CO2 and CO content in the hold air indicates that a cargo fire has begun. CO2 has a smothering action on the seat of the fire because it displaces oxygen.

The vapors of the solvent used during production are denser than air and may thus accumulate in the lower parts of the hold.

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RF Self-heating / Spontaneous combustion

Oil content: 0.5 – 1.0% [1]

Soybean extraction meal is liable to the risk of self-heating/spontaneous combustion.

Soybean extraction meal is assigned to class 4.2, pursuant to the IMDG Code. All types and varieties of pellets, expellers and extracts fall within the class „Seed Cake“ under UN numbers 2217 and 1386.

Due to the use of solvents, extraction meal is largely deoiled, as a result of which the oil content is relatively low in comparison with expeller, generally being < 1.5%.

Smoking/open flames are prohibited during loading, discharge and access to holds.

Causes and promoting factors of self-heating are moisture, oxygen, high fiber content and grain size. However, the residual vapors of the flammable solvents used for extraction are a hazard with extraction meal. Care must be taken to ensure that the extraction meal contains virtually no solvent residues.

The maturing time before ocean transport is of great significance to the promotion of self-heating processes in pressing residues, with both excessively short and excessively long maturing times possibly being disadvantageous. On acceptance, extraction meal should thus exhibit temperatures which are only insignificantly (approx. 10%) above external air temperature. It must be ascertained whether the batch is from the previous year’s production. Unfavorable storage conditions over the period prior to shipping may mean that the product is already at elevated temperature when it arrives on board. Continuous temperature measurements are thus required during loading of the cargo.

The main risk for transport of any cargo which has heated ashore is that the product is loaded at temperatures of above 55°C and retains this temperature in the hold and, due to the poor thermal conductivity of the product, areas with a permanent heat build-up form for the entire duration of transport. The longer the duration of transport, the greater are the consequential losses arising from heating.

In the areas with a heat build-up of above 60°C, the autoxidation process of the feedstuff containing residual oil gradually begins and continues as the unsaturated fatty acids oxidize. The hot spots do not spread much further. The product does, however, dry out, as a result of which moisture migrates upwards from below and water vapor collects in the space between the surface of the cargo and the underside of the hatch covers or weather deck. This accumulation of water vapor combined with maximally airtight hatch covers is the most effective method of fighting fire, as any external supplies of oxygen are blocked off.

Pursuant to the IMDG Code/IMO, ships must be equipped with systems for injecting CO2 or inert gas.

The poor thermal conductivity of extraction meal is also of significance to self-heating. Self-heating may occur simultaneously at various points within the cargo and continue to such an extent that carbonization (release of hydrogen, leaving carbon behind) occurs. The resultant fine-pored carbon has the characteristic of starting to smolder when exposed to oxygen.

Due to the poor thermal conductivity of the product, temperature measurements to detect seats of risk are very difficult. Numerous measurements must be performed and some must also be taken within the heap. Surface measurements alone are not adequate.

The poor thermal conductivity also explains late detection of the seat of a fire. The particular risk is that the cargo burns within the heap without generating appreciable quantities of smoke. The seat of the fire carves out a cavity with the result that fatal accidents may occur when someone steps onto the surface of the cargo and breaks through into such cavities.

In order to be able to detect a cargo fire in good time, it is recommended to make regular gas measurements of the hold air. A rapidly rising CO2 content indicates increased microbial activity combined with evolution of heat within the cargo. This evolution of heat ultimately leads to the spontaneous combustion of the cargo, with evolution of carbon monoxide (CO). The presence of CO gas is considered the most reliable indication of a fire. Levels of 0.002 – 0.005 vol.% of CO in the air are deemed normal, with values rising to above 1 vol.% in a cargo fire.

On unloading, small flames may appear on the exposed surface of a heated cargo: volatile gases which have formed in the cargo over the course of self-heating and have a flash point of around 60°C have spontaneously ignited. These flames do not cause the remainder of the cargo to burn as the ignition temperature of most organic cargoes is of the order of 300 – 500°C. If such small flames or glowing areas of the surface occur in isolated areas, it is helpful to tip the last grab load back down into the area of the hold concerned, so smothering the flames.

The subsequent phases of self-heating possibly culminating in a cargo fire and the action to be taken are described in the article by „Capt. R. Becker: Course of self-heating processes in feedstuffs of animal or vegetable origin containing residual oil, Hamburg, 1996“.

It is possible to conclude from characteristics observable in the ship’s hold, such as temperatures, appearance and odor of the cargo, whether the product was loaded at too high a temperature and whether it has undergone self-heating with microbial spoilage and subsequent autoxidation.

The following features must be observed and recorded for this purpose:

the flow behavior of the cargo in the heap (caked, free-flowing)
the color of the product (normal, brown to black) and the distribution of color differences in the product in the hold
the odor of the product (normal, healthy, fresh, musty, burnt)
the temperature and appearance of the cargo at various depths in the bulk load
the appearance of the cargo surface when the hatches are opened
the appearance of escaping smoke/fumes (steam is white, smoke from overheated product with a temperature of above 90°C is black)

On the basis of this information, it is possible to conclude on the spot whether:

the product was loaded too moist
the product was loaded at too high a temperature after a drying process (toasting)
the product was shipped shortly after production without complying with the maturing time
biogenic self-heating has occurred during the voyage as a result of metabolic processes in microorganisms
self-heating has occurred without a preceding biological self-heating process by chemical autoxidation of unsaturated fatty acids
the product was loaded in a discolored state (brown to black) as a result of drying processes (toasting) performed during manufacture

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RF Odor

Active behavior Soybean extraction meal has a slight, pleasant odor, but should not be stowed together with odor-sensitive products as residues of the solvent used may readily result in odor tainting. The odor of the solvent is, however, not always directly perceptible on the product.
Passive behavior Soybean extraction meal is sensitive to unpleasant and/or pungent odors. Odor-tainted extraction meal is rejected by livestock (especially horses and cattle).

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RF Contamination

Active behavior Soybean extraction meal causes severe dusting during cargo handling, such that there is a risk of dust explosion at dust/air ratios of 20 – 2000 g/m3.
Passive behavior Soybean extraction meal is sensitive to contamination by dust, dirt, fats and oils. The holds or containers should thus contain no residues of previous cargoes, such as ores, minerals, chemicals, salts, fertilizers.

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RF Mechanical influences

No risk.

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RF Toxicity / Hazards to health

Never walk on the surface of the cargo to investigate fires, as breaking through into the cavities carved out by smoldering fires could be fatal.

An increase in CO2 and CO content in the hold air indicates that a cargo fire has begun. Danger: Risk of asphyxiation and poisoning on inhalation. No access is permitted to the hold until it has been adequately ventilated and the atmosphere tested with a gas detector. The CO content may rise from 0.002 – 0.005 vol.% to 1 vol.%. The lethal dose is approx. 0.1 vol.%.

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RF Shrinkage/Shortage

Slight losses (trickle losses) may occur during cargo handling.

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RF Insect infestation / Diseases

Insect infestation, especially by various species of beetles (e.g. khapra beetle), is widespread. On extended storage, there is a risk of mite infestation, which is promoted by heat and moisture.

If required by the consignor or import regulations, fumigation (e.g. with methyl bromide) must be performed.

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