Widely favoured by consumers worldwide, the seafood segment in Asia is no different, where increasing affluence has been fuelling the taste for fresh seafood products.
According to Mary Larkin, group VP of Diversified Business Communications, seafood consumption will continue to grow and most countries will end up being net importers instead of exporters. This is especially so for China and Japan.
Observing a rising demand in Asia for premium species like sea urchin, mussels, lobster, abalone, and salmon, she said, “There has also been significant demand for outsourcing these products, specifically from countries like New Zealand, Australia, Canada, France, and the US. As disposable incomes grow, the demand for non-traditional species grows.”
These consumption patterns will inadvertently lead to a greater demand for live seafood transportation, as items like lobsters spoil quickly after death. With consumption overriding supply in Asia, intercontinental deliveries will increase too.
This will influence developments in cold chain logistics that emphasise on minimising the mortality rates of live seafood, extending storage life, and maintaining quality.
Keeping It Alive
When transporting live seafood, key considerations in limiting mortality include the animals’ respiratory rates, stress handling ability, excrement levels and temperature tolerance.
For instance, reducing temperature helps to reduce the seafood’s metabolic rate and puts it into pseudo-hibernation, thereby enhancing its storage life.
In addition, pseudo-hibernation helps to relieve the stress that live seafood is exposed to during long-distance transport, which has a negative effect on shelf life and quality, resulting in lower market value.
Some stress factors for lobsters include temperature shifts and inadequate warmth or cooling, low humidity, low oxygen, rough handling, and overcrowding due to their nature as solitary animals. As such, they should be packed in individual compartments.
Also integral to the survival of seafood during transportation is managing excrement levels. Waste materials release ammonia over time and have fatal effects when left to build up. For fish, this can also cause increased bacterial levels that result in clogged gills and respiratory problems. To circumvent this, feeding is eliminated the few days prior to shipping.
Chilling is also used to reduce metabolic rates so that fish and other shellfish can achieve lethargy or pseudo-hibernation. This reduces their susceptibility to stress and makes handling easier.
Temperature reduction should be done gradually to help the animals acclimatise, as it may backfire when done too rapidly (eg: prawns losing their claws or legs). Finding the right balance is crucial as over-chilling can easily lead to mortality. Suppliers must take into account the variance in temperature tolerances between species.
Packed For Freight
When preparing live shipments of seafood, it is important to ensure that there is sufficient oxygen for enhanced survival, and minimised movement to prevent damage.
Oxygen is essential for survival across all species, even though this need may manifest in different ways. Among finfish alone, some species make do with natural ventilation while others require the injection of pure oxygen that amounts to 2/3 or 3/4 of the bag volume.
Live shrimps have better survival odds when packed in water and pure oxygen, while live abalones can survive transit times of up to 36 hours with proper packaging and oxygen infusions, as opposed to only six hours without oxygen. Live oysters, on the other hand, require air circulation and should not be packed in containers that are fully sealed.
As oxygen consumption increases at higher temperatures for finfish, the amount of fish packed into each container has to be adapted according to climates.
Adrian F, Melbourne, Australia
Moisture and humidity levels are also integral factors when transporting shellfish. This is maintained by shavings, saw dust and sponges, which prevent excessive wetness that can lead to suffocation.
For example, water is sprayed into shavings when transporting live shrimps, while live abalones are packed into plastic bags filled with pure oxygen and a thin sponge containing seawater.
To prevent damage, movements should also be minimised and interactions reduced. For example, live shrimps should be packed such that they are suspended and unable to move, but not compressed. The claws and pincers of live lobsters and crabs should also be pegged or banded shut to prevent cannibalism or physical damage, especially in the case of crabs where warm temperatures often result in cannibalism.
Cool & Secure
Packaging is crucial in providing satisfactory insulation and refrigeration to maintain low temperatures. This includes the types of bags, coolants, and containers used—all pre-chilled—and their placements.
The items are double bagged in minimum 2-mil watertight plastic bags, before being placed in an insulated foam container with walls that are at least 1.5 inches thick. This in turn, sits inside a corrugated cardboard box for added security. Meanwhile, absorbent pads are placed at the bottom of the foam container to prevent leakages.
Coolants are used to refrigerate the product, as well as to provide insulation from external temperatures. Typically, wet ice is discouraged as it adds on weight and is more susceptible to leakage. Gel packs are used instead, which are commonly placed on the top, bottom and sides of the boxes. Side placements
reduce heat exchange from ambient temperatures, while top and bottom placements help maintain optimal holding temperatures.
Because direct contact with coolants can potentially cause stress and mortality, in most cases a buffer is created by wrapping it with newspaper. Shellfish may also be packed in sawdust or wood shavings to prevent over-chill.
Apart from the functional aspect of packaging, labels are important for ensuring that packages are handled properly. This includes using clear symbols that indicate what is needed eg: refrigeration instead of freezing. To cater for external unforeseen circumstances, bags should not be permanently sealed but twisted, looped, folded over and tied so that re-oxygenation can be provided if delays occur.
Ultimately, cold chain logistics play an indispensable role in exporting live seafood. Yet with the challenge of reducing mortality rates, costs and shipment time while maintaining quality, logistics suppliers have no choice but to innovate, which have also resulted in the use of automated processes like wireless sensors for monitoring temperatures and the development of cavitation techniques to increase survival rates while lowering costs.
Tried & Tested: Ultra Performance Liquid Chromatography
With the increasing popularity of seafood, it is essential that measures are in place for detecting lipophilic marine biotoxins.
Tom Thai, New York, US
Shellfish contaminated with biotoxins may cause diarrhetic shellfish poisoning (DSP) when consumed, resulting in intestinal tract inflammation and diarrhoea. This is caused by lipophilic marine biotoxins, which include okadaic acid (OA) and its derivatives, dinophysistoxins (DTX1, DTX2 and DTX3) that are all regulated under EU legislation. Nonetheless, other unregulated toxins exist, where detection is made complex due to the variety of physiochemical properties found in biotoxins.
The official method before July 2011 was a mouse bioassay, but it was deemed unethical and not robust enough for determining trace amounts of specific toxins. Time consuming and expensive, accuracy was also subjected to interferences by other lipids.
It was eventually replaced with liquid chromatography mass spectrometry (LC/MS/MS), which comprises a fixed extraction procedure followed by conventional LC separation with either an acidic or alkaline mobile phase and detection by tandem quadrupole MS.
To speed things up however, Waters has developed the UPLC/MS/MS system that produces a faster routine analysis—five minutes instead of 20—than the conventional LC method under alkaline conditions. It is also capable of tracking additional non-regulated compounds.
The system utilises an Acquity ultra performance liquid chromatography (UPLC), which allows reduced analytical run times without compromising peak resolution and quality, and the Xevo TQ-S, a tandem quadrupole mass spectrometer. The latter provides ultra-high sensitivity for the detection and simultaneous acquisition of multiple reaction monitoring (MRM) transitions in alternating electrospray positive (ESI) and negative ionisation modes (ESI)—a requirement for analysing lipophilic marine biotoxins.
The UPLC method has been shown to provide good results for the various toxins classes. It has a good sensitivity for various toxins with a validation level that is 0.125 times that for regulated toxins, and is capable of achieving a signal-to-noise ratio above three.
More importantly, it can determine toxins for which standards are still unavailable. Those are determined by MRM transitions and based on the structural relation with toxins that have an available standard.
This ultimately results in a fourfold increase in speed, in part due to the IntelliStart technology, which simplifies the use of LC/MS systems by automating instrument setup, compound tuning and performing system suitability checks. These settings can also be easily implemented into other laboratories as it is included in the Quanpedia database.