Why Are There So Many Soya Bean Claims?

In 2023, the global soya bean market (also known as soybeans and soyabeans) was valued at over USD 200.37 billion¹, and it is projected to grow to USD $259 billion by 2030². The shipping industry plays a significant role in supporting this global industry, but behind these impressive figures lies a perilously narrow window for safe ocean transport. Despite being loaded in sound condition and carried by well-maintained vessels on unexceptional voyages, soya beans continue to arrive in a deteriorated condition far too often. Claims related to spoilage frequently run into millions of dollars, exposing shipowners, operators, and marine insurers to significant financial risk.

Why are soya bean claims becoming so frequent??

The answer lies in the unstable nature of soya beans themselves. The oil-rich composition that makes them valuable also makes them highly susceptible to spoilage. Even when fully compliant with moisture specifications at the time of loading, soya beans have a much shorter shelf life than other grains and are prone to self-heating. Risk increases significantly with longer voyages, and when spoilage occurs, it can escalate rapidly, leading to severe damage, caking, mould growth, and discolouration.

Given the vastness of the soya bean trade and the financial consequences of spoilage claims, how can operators ensure the safe transportation of this unstable cargo and mitigate the associated commercial risks?

Why are soya beans more susceptible to self-heating than other grain and oilseed cargoes?

Unlike cereal grains such as wheat, barley, rice, and sorghum, which have stable moisture content and are rarely subject to self-heating, soya beans are inherently more unstable due to their high oil content. Soya beans consist of one-fifth (20%) oil, and the oil is completely immiscible with water, which means that moisture in soya beans is concentrated in the non-oily parts of the seed. Although soya beans are traded on comparable commercial moisture specifications as cereal grains, typically 13-14%, the risk of spoiling is actually the same as if the moisture content was one-fifth higher, i.e. around 16.5-17.5%.

Mould spores are present in all grain cargoes, but typically remain dormant when moisture content is low.

In soya beans, however, the higher moisture concentrated in the non-oily part of the bean creates excess humidity within the cargo. As a result, mould spores will break dormancy and begin to proliferate. Mould growth is microscopic. It’s not usually visible, at least in the early stages, but it generates a lot of heat, and as the heat is generated, the temperature goes up, and higher temperatures generate even faster mould growth, producing a self-accelerated process referred to as “self-heating”.

Once this process has started, the only way of preventing further deterioration is to discharge the cargo as soon as possible and to commence processing immediately thereafter.

At what moisture content do soya beans become unstable?

Soya beans are unique amongst oilseeds as they are traded at comparable moisture levels as non-oily cereals.

It is widely accepted that oilseeds like rapeseed, with around 40% oil content, have a safe moisture threshold of about 8%-9%, and are accordingly usually traded on contracts reflecting this.

It follows that soya beans, with 20% oil, should have a maximum safe moisture content of roughly 11.5%, and indeed this is confirmed by published data. However, soya beans are often traded at moisture levels up to 14%, making them highly susceptible to self-heating, particularly on long voyages.

The vast majority of Brazilian soya beans are shipped under standard contracts drawn up by the Brazilian Association of Grain Exporters ANEC (ANEC 41), in accordance with standards set by the Ministry of Agriculture, Livestock, and Supply (MAPA).

The moisture content allowed under ANEC contracts is an average of 14%. It’s important to note that a cargo with a 14% average temperature might be made up of soya beans with a moisture content as high as 17% in some locations, or as low as 11% in others, and these figures will not appear on the cargo specifications.

So, the risk depends on how homogeneous the cargo is as well as what the average moisture content is.

Even when cargo is loaded completely on-spec, with a uniform moisture content throughout and exhibiting no identifiable problems, at least in commercial terms, soya beans have a limited shelf life.

The primary trade route for soya beans is from South America, particularly Brazil, to China, accounting for nearly three-quarters of Brazil's soybean exports. These voyages typically take around 40 days or more, depending on loading and discharge speeds.

In addition to moisture levels, other important factors involved in the safe carriage of soya beans are storage time and loading temperature, with mould growth and spoilage accelerating the higher the moisture and temperature.

Researchers from the University of Georgia considered the moisture and temperature thresholds that make soya beans vulnerable to spoilage. According to their data, even at a temperature as low as 15.6°C (60°F), soya beans with a moisture content of 12.6% reach the stability limit of 70% equilibrium relative humidity (ERH), which refers to the relative humidity of the air in the interstitial spaces between the individual soya beans making up a cargo.

At higher temperatures, such as 26.7°C (80°F), this stability threshold drops to around 11.5%, indicating that soya beans are increasingly unstable at typical moisture levels.

Tables published by North Dakota State University³ estimate the storage life of soya beans loaded at approximately 27°C (80°F), with 13% moisture having a shelf life of 40 days, and soya beans loaded at 14% moisture having only 20 days. Soya beans meeting sale contract specifications can arrive undamaged in Europe, but extended voyage times to China increase the risk of spoilage.

Because of the contractual moisture specifications and typical load port cargo temperatures, soya bean cargoes are almost always loaded in an unstable condition and are liable to self-heat and deteriorate if they remain on board for too long.

Although most cargoes arrive in acceptable condition, the reality is that many shipments are already in the early stages of self-heating by the time they reach their destination. They typically arrive just in time before visible signs of damage appear. However, any voyage delays dramatically increase the risk of widespread heating, caking, mould growth, and discolouration. Even without delays, each cargo behaves differently, making spoilage unpredictable.

How can shipowners effectively manage the risk of spoilage in transit?

Ventilation will not prevent self-heating in soya bean cargoes. When the equilibrium relative humidity (ERH) exceeds 65-70% at loading (which is generally the case for soya beans traded under customary contract specifications), self-heating becomes inevitable if given enough time.

Natural ventilation can only affect the surface layers and cannot prevent mould growth or heating within the bulk of the stow.

Receivers often confuse ship and shore-based ventilation. Forced ventilation, used in shore silos, involves powerful fans pushing cool, dry air through the bulk of the cargo to temporarily stabilise it. However, this method is not available on ships even if equipped with mechanical ventilation. Only surface ventilation is available during bulk carriage by sea.

Ventilation serves only to reduce ship sweat, referring to condensation caused when the temperature of the vessel's steel structures falls below the dew point of the headspace air.

While natural ventilation can reduce condensation, it cannot prevent the deeper effects of self-heating. In fact, excessive ventilation with much colder air can lead to surface crusting, creating localised moisture gradients that result in mould formation just below the surface.

Ultimately, the underlying cause of both self-heating and ship sweat is the inherent instability of the cargo and the duration of the voyage, not the cargo ventilation during the voyage.

Notwithstanding the wealth of evidence to the contrary, receivers frequently point to ventilation issues as the primary cause of damage, and ventilation records often come under intense scrutiny.

Some courts can be persuaded by evidence alleging inadequate ventilation practices, even when the root cause of damage can lie in the inherent instability of the cargo itself.

Any allegations of problems relating to the way the cargo has been ventilated during the voyage can result in findings of carrier responsibility. To mitigate this risk, ventilation records must be meticulously maintained to demonstrate that the cargo was properly cared for.

If a Master suspects cargo damage, an independent expert should be appointed to attend to the ship as soon as possible. Potential shipboard problems, like seawater ingress or fuel tank heating, need to be excluded, and representative sampling should begin as soon as discharging commences.

Finally, it is imperative that the discharged product is processed without delay.

Most soya beans are crushed to extract crude soya bean oil, and the losses incurred in terms of refined oil yield and extra consumables, as a result of self-heating, are generally relatively modest and straightforward to verify through daily production data from the crushing and refining processes.

The solid residue remaining after crushing – the soya bean meal – is rich in protein and valuable as animal feed. Prolonged exposure of the protein to high temperatures can result in discolouration or denaturing of the protein, affecting nutritional and hence commercial value. Again, this can be verified through daily production data from the production process.

Recent developments: industry shifts in moisture standards

Recent changes in grain safety standards, including updates to China's domestic soybean standard for grain safety storage, reflect a growing recognition that moisture thresholds must account for temperature fluctuations.

The new Chinese national standard came into effect in November 2024, introducing stricter guidelines, with maximum moisture content dropping to as low as 11.0% at 35°C (95°F). This is a significant development.

Despite efforts made in 2023 to lower the maximum permitted grain moisture content from 14% to 13%, Brazil has maintained higher moisture content standards, permitting up to 14% moisture. This divergence in moisture regulations could lead to significant trade frictions.

Disputes between shippers and buyers may arise more frequently as cargoes with higher moisture levels fail to meet China’s new safety thresholds upon arrival, further complicating an already volatile trade and impacting future claims for self-heating and spoilage.

So far, Brookes Bell has seen an upsurge in 2024 soybean damage cases, with a notable number of instances of highly unstable beans loaded with sound beans, which gives a much more polarised pattern of damage. This is probably due to the extreme rainfall that caused destructive floods in Brazil earlier this year, with associated logistics issues and delays.

Assistance with soya bean cargo claims is here

Brookes Bell has extensive experience with claims arising from self-heating of soya beans in many countries worldwide. If you suspect or are dealing with a spoiled soya bean cargo, our scientists can provide comprehensive, evidence-backed advice and solution-based assistance.