In 2023, the global soya bean market (also known as soybeans and soyabeans) was valued at over USD 200.37 billion, and it is projected to grow to USD $259 billion by 2032.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.
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.
The article also goes into detail at what moisture content soya beans become unstable. It also includes information on recent development: industry shifts in moisture standards. Read the article in full: here