Citrus Pellets

Infobox on Citrus Pellets
Example of Citrus Pellets
Facts
Origin	This table shows only a selection of the most important countries of origin and should not be thought of as exhaustive. Europe Africa Asia India America: Brazil Australia
Stowage factor (in m3/t)	1.68 m3/t
Angle of repose	approx. 40°
Humidity / moisture	Relative humidity: 70% Water content: 8 - 12% Maximum equilibrium moisture content: 70%
Oil content	0.1 - 1.0%
Ventilation	Recommended ventilation conditions: surface ventilation. As with bulk cargoes of expeller, pellets are also often not ventilated. In order to avoid moisture damage on the surface of the cargo, ventilation must not be performed with cold external air. The ventilation system must then be switched to return air.
Risk factors	Citrus pellets are liable to the risk of self-heating/spontaneous combustion.

Citrus Pellets

Description

Citrus pellets are an animal feed produced from byproducts of citrus processing. The pellets are composed of peel, pulp and seeds of several species of citrus, dried, to which binders (e.g. molasses, fat or colloidal clays) are added. Hence, the composition is pressed in pelletizing machines or extruders to form cylindrically shaped pellets. Pelletizing reduces the volume, thus enabling better utilization of transport/storage capacity. Another basic material is citrus extraction meal, which is obtained during oil extraction from the seeds and is then pelletized. Pellets generally have the same characteristics (i.e. particularly with regard to oil and water contents) as the original plant residues. However, there is a difference between expeller pellets and extraction meal pellets depending on their origin.

Quality / Duration of storage

Citrus pellets have a brown colour with yellow spots and should be well matured to allow overseas shipment. How long the product should mature is dependent on the oil content.

Shippers should provide certificates in which the moisture, residual oil content and maturing time is mentioned.
<1,5% oil content is extraction meal; >1,5% oil content is expeller.

Applications

Used for feedstuff, especially for dairy cattle, fattened beef cattle and sheep.

Shipment / storage

Citrus pellets are chiefly shipped in bulk and the stowage spaces should allow mechanical ventilation. The product is not to be stowed near/over heat sources (i.e. fuel tanks, hot pipework, engine-room bulkhead etc.)

The travel temperature should preferably be between 5 and 25°C. Temperatures of up to 30°C are admissible for short periods, providing the critical water content of the product is not exceeded - in order to avoid self-heating -.

Product temperatures of 25 - 55°C may occur in tropical ports. If rising >55°C and increasing further, closing of hatch openings and injection of CO₂ or inert gas should be considered.

At temperatures of 35 - 40°C within the stow, fat degradation and thus the self-heating process is activated.

Humidity/Moisture

Designation	Humidity/water content
Relative Humidity	70%
Water content	8 - 12%
Maximum equilibrium moisture content	70%

Pellets 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%), seawater, rain).

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

Ventilation
Citrus pellets require particular temperature, humidity/moisture and ventilation conditions. Recommended ventilation conditions: surface ventilation. As with bulk cargoes of expeller, pellets are also often not ventilated. In order to avoid moisture damage on the surface of the cargo, ventilation must not be performed with cold external air. The ventilation system must then be switched to return air.

Due to the principal causes of self-heating in vegetable pressing residues, two problems arise with regard to ventilation. At an excessively high product water content, localized overheating caused by enzymes or bacteria results in self-heating. The resultant heat must be dissipated by constant ventilation by means of a good ventilation system. Drying by ventilation is useful, but its effectiveness is questionable because, as heating proceeds, increasingly large quantities of water vapor are released. The activity of the initiating microorganisms is not suppressed by nonventilation of the hold as some of the thermophilic (= heat-loving) bacteria are anaerobic organisms (which require no oxygen supply to stay alive). In a product with an excessively low water content, which must be expected to undergo oxidative fat cleavage, the supply of oxygen must be interrupted as this process would otherwise be accelerated. Any attempt to cool the cargo by ventilation supplies air, so further promoting the oxidation process.

Ventilation is helpful in the first case, but hazardous in the second. The correct ventilation measures may only be implemented if the characteristics (loading temperature, water content, duration of prior storage) of the cargo are known. However, if a large batch is made up of various sub-batches, it is entirely possible for both the above-stated causes to occur in the same heap of cargo.

Solvent vapors from pellets made 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. 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.

Biotic activity
Citrus pellets display 3rd order biotic activity. They belong 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.

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 from extraction meal are denser than air and may thus accumulate in the lower parts of the hold.

Risk factors

Self-heating / Spontaneous combustion
Oil content: 0.1 - 1.0%. Citrus pellets are liable to the risk of self-heating/spontaneous combustion. Since oil content is of central significance to the risk of self-heating, it should be determined whether the pellets were made from expeller or extraction meal, as the residual oil content of extraction meal (< 1.5%) is substantially lower than that of expeller. The present oil content is indicative of a product based on extraction meal.

Smoking/open flames are prohibited during loading, discharge and access to holds. Causes and promoting factors of self-heating are moisture, oxygen, elevated residual oil content, high fiber content and grain size. Oxygen promotes oxidative fat cleavage. The principal cause underlying self-heating caused by oxidative fat cleavage is an excessively high residual oil content. In pellets, a residual oil content in excess of 7 - 10% promotes oxidation processes.

An elevated unsaturated fatty acid content in the residual oil constitutes a very serious storage risk as such Fatty Acids have a strong tendency to undergo autoxidation with (atmospheric) oxygen, plentiful supplies of which are also available in a feedstuff cargo, to form saturated fatty acids. This autoxidation, as a kind of flameless combustion, results in considerable evolution of heat which may result in a hazardous build-up of heat in the feedstuff cargo if the heat cannot be dissipated.

The maturing time before ocean transport is of great significance to the promotion of self-heating processes in pellets, with both excessively short and excessively long maturing times possibly being disadvantageous. On acceptance, pellets 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 pressing residues 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.

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
  
  

Odor
Active behavior: Citrus pellets have a pleasant, sweetish odor of fruit and should not be stowed together with odor-sensitive products.
Passive behavior: Citrus pellets are sensitive to unpleasant and/or pungent odors. Odor-tainted pellets are rejected by livestock (especially horses and cattle).

Contamination
Active behavior: Citrus pellets cause dusting during handling. There is a risk of dust explosion at a dust/ air ratio of 20 - 2000 g/m3.
Passive behavior: Citrus pellets are 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.

Toxicity / Hazards to health
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 (fatal) dose is approx. 0.1 vol.%.

Shrinkage / Shortage
Slight losses (trickle losses) may occur during cargo handling.

Insect infestation / Diseases
Insect infestation, especially by various species of beetles (e.g. khapra beetle), is more frequent in pellets based on expeller than those based on extraction meal. Increasing levels of humidity/moisture and heat promote mite infestation. If required by the consignor or import regulations, fumigation (e.g. with methyl bromide) must be performed.

Reference is made to the relevant IMO regulations on hazardous cargo ("Seed Cake").

Note:(Source including Transport Information Service of the GDV)