Hazelnuts [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 Haselnüsse
English Hazelnuts, cobnuts, filberts
French Noisettes
Spanish Avellanas
Scientific Corylus avellana, Corylus maxima
CN/HS number * 0802 21 ff.

(* EU Combined Nomenclature/Harmonized System)

Product description

The hazelnut is the single-seeded indehiscent fruit of the hazel tree (filbert family, Corylaceae), which grows to a height of 7 m. The nut ripens from mid-August, sits in a slit, cupule-type husk formed from bracts and has a relatively thick, hard, woody shell, which constitutes approx. 55% of its weight. The edible kernel within consists of delicious-tasting hard flesh enclosed in a brownish seat coat.

The hazelnut kernel is surrounded by a brown seed coat, which contains antioxidants which protect the oil-rich seed from atmospheric oxygen so preventing it from becoming rancid (oxidative rancidity).

Hazelnuts are shell fruit (nut types). Because of their similar characteristics with regard to transport, particularly their high oil content, their requirements regarding care during storage and transport are the same as those of oil-bearing seeds/fruits.

To harvest them, sheets of cloth are laid beneath the trees and the branches of the trees are then shaken. The nuts are subsequently dried in a well-ventilated place.

German-produced hazelnuts are generally sold with their shell on, but can only meet a small proportion of German demand. For this reason, unshelled and shelled hazelnuts (hazelnut kernels) are imported into Germany from the countries of origin listed below.

Oil content:

hazelnuts (unshelled) 50 – 62% [1]
hazelnut kernels 60 – 68% [1]

Quality / Duration of storage

Depending on shape, a distinction is drawn between European hazelnuts or filberts (cobnut, Corylus avellana), which are roundish, and Lambert’s nuts (giant filbert, Corylus maxima), which are oblong.

Hazelnuts must be clean, tender and fresh to the taste and have a large kernel and a thin shell; they must not taste bitter, sour or rancid. Mixtures of nuts from various years‘ harvests are inadmissible.

Hazelnuts may be kept for approx. 12 months at temperatures of -3 – 0°C [5] (cold storage) and a relative humidity of 65 – 70% [1].

Hazelnut kernels, on the other hand, may be kept for just a few weeks at temperatures of 2 – 8°C and approx. 65% relative humidity. At room temperature there is a risk of the highly fatty kernels turning rancid.

It is very important for the surveyor to ascertain the year of harvest: it must be taken into consideration that the nuts may be mixed with nuts from the previous year’s harvest. This possibility must not be disregarded when determining whether or not loss has occurred in transit. Nuts from the previous year’s harvest have a tendency to beetle infestation and rancidity.

Intended use

Most of the nuts produced are processed by the confectionery and bakery industries (lebkuchen, macaroons, hazelnut puree, hazelnut oil => nougat, etc.).

Apart from this industrial processing, hazelnuts are also eaten raw as snacks (trail mix) and sold as kernels and grated or ground etc. for use in muesli, salads and the like.


(Click on the individual Figures to enlarge them.)

Photo, hazelnut

Figure 1
Photo, hazelnuts

Figure 2
Photo, hazelnuts

Figure 3

Countries of origin

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

Europe Turkey, Italy, France, Spain, Greece, Cyprus, Russia
America USA

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Hazelnuts are packaged in, among other things, woven polysacks (5 – 25 kg), flat jute fabric bags (10 – 50 kg) and cartons (10 kg).

Vacuum packaging is best, as it protects the nuts from atmospheric oxygen.

The risk of rancidity is reduced if the packaging is lined with plastic.

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Symbol, general cargo

General cargo


Means of transport

Ship, truck, railroad

Container transport

Ventilated containers (coffee containers), if the lower limits set for the water content of goods, packaging and flooring and the oil content of the goods are complied with and if protection against solar radiation is ensured (risk of self-heating).

Cargo handling

In damp weather (rain, snow), the cargo must be protected from moisture, since it may lead to mold, spoilage and self-heating as a result of increased respiratory activity.

No hooks should be used with bagged cargo, so as to prevent damage to the bags and loss of volume.

Stowage factor

2.00 m3/t (flat jute fabric bags, 10 – 50 kg) [1]
1.98 – 2.12 m3/t (shelled in bags) [14]
2.41 m3/t (unshelled in bags) [14]

Stowage space requirements

Cool, dry, good ventilation


Fiber rope, thin fiber nets

Cargo securing

In order to ensure safe transport, the bags must be stowed and secured in the means of transport in such a manner that they cannot slip or shift during transport. Attention must also be paid to stowage patterns which may be required as a result of special considerations, such as ventilation measures.

In the event of loading as general cargo, dunnage should be used to protect against damage:

Floor dunnage: criss-cross dunnage and packing paper
Side dunnage: lining with wooden dunnage and mats or jute coverings: protection from metal parts of the ship, since traces of metal promote cargo rancidity due to autoxidation.
Top dunnage: important for voyages to cold regions (winter), since sweat may drip onto the cargo.

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Risk factors and loss prevention

RF Temperature

Hazelnuts require particular temperature, humidity/moisture and ventilation conditions (SC VII) (storage climate conditions).

For this reason, precise details should be obtained from the consignor as to the travel temperature to be maintained.

Designation Temperature range Source
Favorable travel temperature range 2 – 4°C [1]
2 – 8°C [3]
-3 – 0°C [5]
2 – 4°C [14]

The stated travel temperatures are the ideal temperatures for achieving the longest possible storage life, but travel temperatures of approx. 5 – 25°C are also feasible (depending on journey length), so it is not absolutely necessary for the product to be transported as chilled goods.

Temperatures > 30°C should not prevail for a long period, as such temperatures promote respiration of the cargo and cause self-heating.

Heated nuts become inedible due to rancidity. Light turns shelled nuts (hazelnut kernels) rancid more quickly than unshelled nuts.

Shelled nuts must not be stowed near heat sources. Stowing next to the engine room bulkhead or on heated oil tanks causes drying-out or „roasting“ of the hazelnut kernels.

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RF Humidity/Moisture

Hazelnuts require particular temperature, humidity/moisture and ventilation conditions (SC VII) (storage climate conditions).

Designation Humidity/water content Source
Relative humidity 60 – 70% [1]
Water content 4.3 – 12% unshelled [1]
11 – 13% unshelled [14]
5 – 6% shelled [1]
6% shelled [14]
Maximum equilibrium moisture content 65% [1]

Precise details should be obtained from the shipper as to the relative humidity to be maintained during the journey.

Water contents of 4 – 12% are common; 6% is deemed dry for shipment. At water contents > 12%, hazelnuts may become rancid. Damage due to moisture and mold may be caused by ship and container sweat.

Sodden bags must be rejected. Seawater, rain and condensation water promote hydrolytic/enzymatic fat cleavage, which may lead to self-heating as a result of increased respiration (see RF Self-heating/Spontaneous combustion). Avoid wettening liquids.

Hazelnut kernels should have a water content of 6% max., as an excessively high water content may lead to self-heating, rapid spoilage due to anaerobic respiration and mold.

The sorption isotherm for fresh hazelnuts rises gently, indicating relatively weak sorption behavior. However, hazelnuts with a water content of 5 – 6% are at equilibrium with a relative humidity of 70 – 75%, i.e. the mold growth threshold is reached even at these low water contents.

Sorption isotherm

Figure 4

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RF Ventilation

Hazelnuts require particular temperature, humidity/moisture and ventilation conditions (SC VII) (storage climate conditions).

Recommended ventilation conditions: air exchange rate: at least 10 changes/hour (airing)

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RF Biotic activity

Hazelnuts display 2nd order biotic activity.

They are living organs in which respiration processes predominate, because their supply of new nutrients has been cut off by separation from the parent plant.

Care of the cargo during the voyage must be aimed at keeping decomposition processes at the lowest possible level, so as to keep within limits any losses in quality caused by the emission of CO2, heat and water vapor.

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RF Gases

Hazelnuts (especially when fresh) produce ripening gases (particularly CO2) as a result of the respiration processes which continue postharvest. 

If ventilation has been inadequate (frost) or has failed owing to a defect, life-threatening CO2 concentrations or O2 shortages may arise. Therefore, before anybody enters the hold, it must be ventilated and a gas measurement carried out. The TLV for CO2 concentration is 0.49 vol.%.

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RF Self-heating / Spontaneous combustion

Oil content:

hazelnuts (unshelled) 50 – 62% [1]
hazelnut kernels 60 – 68% [1]

Because of their tendency to self-heating, hazelnuts may behave like substances from Class 4.2 of the IMDG Code. See also IMO Code of Safe Practice for Solid Bulk Cargoes.

However, self-heating occurs relatively seldom with hazelnuts and, if it does, it is generally as a result of external influences such as heat and moisture.

Excessive stack pressure leads to self-heating, especially in the case of fresh, crushed hazelnuts. Oils which have accumulated in the jute packaging fabric encourage this behavior.

As a basic principle, a high oil content (especially in hazelnut kernels, see above) encourages the tendency to self-heating.

Nuts from the previous year’s harvest have a particular tendency to rancidity.

Fat decomposition in hazelnuts leads to the risk of self-heating and, ultimately, to a cargo fire.

Fat decomposition may proceed as follows:

by hydrolytic/enzymatic fat cleavage or
by oxidative fat cleavage

Hydrolytic/enzymatic fat cleavage:

If the critical water content of the hazelnuts is exceeded, this promotes hydrolytic/enzymatic fat cleavage. Fat-cleaving enzymes are activated by the elevated water content. The additional action of light and heat may accelerate this process. Free fatty acids sometimes have an unpleasant odor and taste. In the event of extended storage or improper cargo care, these cause the cargo to become rancid.

The free fatty acids formed are consumed by respiration processes in the hazelnuts to form carbon dioxide and water, a process which is associated with considerable evolution of heat.

Self-heating of hazelnuts is an extremely vigorous process, as the consumption of fatty acids by respiration processes is associated with a considerably greater evolution of heat than is the case with the respiration equation for carbohydrates. Here too, as with cereals, the spoilage process proceeds in a type of chain reaction, because heat and water are formed by the fatty acids consumed by respiration, which in turn contribute to an intensification of the process.

The self-heating of hazelnuts requires only a small seat of moisture, so that within just a few hours heating may occur at moist points for which weeks or months would be required in goods dry on shipment.

Fresh hazelnuts with a high water content tend in particular towards rapid self-heating and may also ignite. Self-heating of hazelnuts leads not only to a reduction in the utility value of this product (rancid odor and taste) but also has a qualitative and quantitative effect on oil yield. The color and bleachability of the oils are also negatively affected. The oil obtained complicates refining of the crude oils in subsequent processing, because a higher free fatty acid content makes decolorization substantially more difficult.

Hydrolytic/enzymatic fat cleavage and respiration may be limited by low temperatures; however, this may only be affected to a limited degree during transport. It is therefore important to ensure storage stability by complying with the limit values for the water content of the goods.

Oxidative fat cleavage:

Food components frequently react with atmospheric oxygen in spoilage processes. Atmospheric oxygen may enter into an addition reaction with unsaturated fatty acids through the simultaneous assistance of light, heat and certain fat companion substances, and possibly also traces of heavy metals. Rancidity caused by oxidative fat cleavage is particularly noticeable in the case of shelled hazelnuts, because the shelling process results to a certain degree in exposure to atmospheric oxygen or to the steel parts of the ship or the container walls, if not carefully covered. It is therefore absolutely essential to store hazelnuts in the dark and to protect them from oxygen and metal parts, since otherwise they become brown-colored and develop a rancid odor and taste.

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RF Odor

Active behavior Hazelnuts do not release any odor.
Passive behavior Hazelnuts are sensitive to unpleasant and/or pungent odors.

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RF Contamination

Active behavior The high oil content of the goods frequently causes dark fat stains to appear on the bags, which must therefore be kept from coming into contact with goods sensitive to contamination, such as baled goods, tea chests, marble etc..

Hazelnuts in bags must not be stowed together with fibers or fibrous materials, either, since oil-impregnated fibers accelerate self-heating processes.

Hazelnuts often also contain a high proportion of fine dust or sand.
Passive behavior Hazelnuts are sensitive to dust, dirt, fats and oils. The holds or containers must accordingly be clean and in a thoroughly hygienic condition before loading.

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RF Mechanical influences

Hazelnuts are impact-sensitive and fragile and it is therefore necessary to avoid particularly high stack pressure.

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RF Toxicity / Hazards to health

Evolution of CO2 due to respiration, especially with fresh goods. Take care when entering the hold. Use gas detector.

Danger: hazelnuts may contain aflatoxin. The molds Aspergillus flavus and Aspergillus parasiticus produce the toxin aflatoxin, which may be present in the cargo as a result of an attack by the above-mentioned mold types (see risk factors Humidity/Moisture and Ventilation). In general, this is „country damage“, i.e. the toxin is already present in the hazelnut at the time of harvesting. As a rule, aflatoxin is only found in individual nuts. If batches of hazelnuts intended as a human foodstuff are affected by this toxin, the product can no longer be approved for human consumption. Hazelnuts affected by aflatoxin cannot readily be distinguished from the other nuts in a batch. The toxin may be detected using UV light.

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RF Shrinkage/Shortage

Weight loss of up to 1% occurs due to moisture loss.

In the case of nuts which are empty, rotten or infested with the hazelnut weevil, acceptable losses of approx. 7 – 12% per packing drum may occur.

Valuable cargo, so at high risk of theft.

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RF Insect infestation / Diseases

On acceptance, the cargo must be inspected for insect infestation. An inspection certificate should be issued.

Insect infestation (hazelnut weevil) is a problem occurring particularly frequently in hazelnut kernels. It generally originates in the producing country and makes the cargo inedible and worthless. Imports from Turkey exhibit an elevated susceptibility to damage in the early summer (products from previous harvest). As a consequence, the goods must be fumigated and often also mechanically post-treated.

On acceptance of a consignment, particular attention should be paid to „hidden“ or „internal“ infestation. Consult a surveyor and ensure that an inspection certificate is issued.

During the voyage, infestation may also occur due to „defectors“, but then the insects are to be found in the sacking and not in the product.

Mites, cockroaches, sawtoothed grain beetles, flour beetles, meal moths, dried fruit moths and rats and mice may attack hazelnuts. Nuts from the previous year’s harvest have a particular tendency to beetle infestation.

The quarantine regulations of the country of destination must be complied with and a phytosanitary certificate and fumigation certificate may have to be enclosed with the shipping documents. Information may be obtained from the phytosanitary authorities of the countries concerned.

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