258
where urchin roe is still a relatively new product, quality is not as important as in
Japan (Sun and Chiang 2015).
Uni may be sold fresh, but is also steamed, baked, sautéed, or frozen. Uni used
for sushi is brined and treated with alum. It may also be coloured. Colour and condition are important for determining grades of uni, and a bright orange product is the
most desirable. The salted gonadal tissue from the sea urchin may also be fermented,
producing a paste (neriuni). Also, a more watery preparation, mizuuni, is prepared
using a dry cure process. Doro uni is made by washing the gonadal tissue with dilute
alcohol, then draining it, and mixing with salt. Sea urchins are cultured in China,
and some wild harvested animals are held in raceways where they are fed a highnutrition diet. Proper husbandry and nutrition can yield over a 40% increase in
gonadal production (Batista 2007).
Sea urchin processors have little control over the quality of extracted roe, as this
mainly depends on where and when the sea urchins were harvested. Buyers for
processing companies try to assert some quality control dockside by sampling the
catch before they agree to purchase, which allows them to either reject the harvest
outright or pay the fishermen a lower or higher price depending upon the quality
(Sun and Chiang 2015).
In a study examining the quality and shelf life during refrigerated storage of
fresh roes of Paracentrotus lividus sold in Palermo, Italy, it was determined that roes
were sensorially acceptable for up to 72 h, Listeria and Salmonella were not isolated, Vibrio was isolated in 71.43% of the samples (Panebianco et al. 2011).
4.2.3 Postharvest Handling of Sea Urchins
4.2.3.1 Live Transport of Sea Urchins
Sea urchins are relatively hardy animals, and if handled correctly, they can survive
considerably out of the water without suffering high mortality and quality loss, even
after immersion in sea water. In a previous trial, green sea urchins collected were
transported to a live holding system. They were held in this system until the beginning of the experiment (approximately 6 h). Two temperature regimes were applied
(ambient and 4 °C up to 28 h) and (5 and 3 °C up to 56 h). They were held in an
insulated plastic container. Inside the container the urchins were covered with hessian sacks that had been soaked in seawater. The maximum transport period for an
average transport temperature of 14 °C was found 14 h, at 5.0 °C was 36 h, and at
3.0 °C was 44 h. If the transport period is longer then it becomes necessary to transport sea urchins immersed in cool, seawater. There are systems designed to carry
live seafood in chilled shipping containers and although they are not specifically
designed for sea urchins, they may also be suitable for transporting sea urchins for
long distances and over extended periods (James and Evensen 2018). Holding and
shipping of sea urchins in recirculating sea water may open options on keeping
them alive for long periods especially if ammonia stripping is carried out. Still, such
4 Echinoderms
where urchin roe is still a relatively new product, quality is not as important as in
Japan (Sun and Chiang 2015).
Uni may be sold fresh, but is also steamed, baked, sautéed, or frozen. Uni used
for sushi is brined and treated with alum. It may also be coloured. Colour and condition are important for determining grades of uni, and a bright orange product is the
most desirable. The salted gonadal tissue from the sea urchin may also be fermented,
producing a paste (neriuni). Also, a more watery preparation, mizuuni, is prepared
using a dry cure process. Doro uni is made by washing the gonadal tissue with dilute
alcohol, then draining it, and mixing with salt. Sea urchins are cultured in China,
and some wild harvested animals are held in raceways where they are fed a highnutrition diet. Proper husbandry and nutrition can yield over a 40% increase in
gonadal production (Batista 2007).
Sea urchin processors have little control over the quality of extracted roe, as this
mainly depends on where and when the sea urchins were harvested. Buyers for
processing companies try to assert some quality control dockside by sampling the
catch before they agree to purchase, which allows them to either reject the harvest
outright or pay the fishermen a lower or higher price depending upon the quality
(Sun and Chiang 2015).
In a study examining the quality and shelf life during refrigerated storage of
fresh roes of Paracentrotus lividus sold in Palermo, Italy, it was determined that roes
were sensorially acceptable for up to 72 h, Listeria and Salmonella were not isolated, Vibrio was isolated in 71.43% of the samples (Panebianco et al. 2011).
4.2.3 Postharvest Handling of Sea Urchins
4.2.3.1 Live Transport of Sea Urchins
Sea urchins are relatively hardy animals, and if handled correctly, they can survive
considerably out of the water without suffering high mortality and quality loss, even
after immersion in sea water. In a previous trial, green sea urchins collected were
transported to a live holding system. They were held in this system until the beginning of the experiment (approximately 6 h). Two temperature regimes were applied
(ambient and 4 °C up to 28 h) and (5 and 3 °C up to 56 h). They were held in an
insulated plastic container. Inside the container the urchins were covered with hessian sacks that had been soaked in seawater. The maximum transport period for an
average transport temperature of 14 °C was found 14 h, at 5.0 °C was 36 h, and at
3.0 °C was 44 h. If the transport period is longer then it becomes necessary to transport sea urchins immersed in cool, seawater. There are systems designed to carry
live seafood in chilled shipping containers and although they are not specifically
designed for sea urchins, they may also be suitable for transporting sea urchins for
long distances and over extended periods (James and Evensen 2018). Holding and
shipping of sea urchins in recirculating sea water may open options on keeping
them alive for long periods especially if ammonia stripping is carried out. Still, such
4 Echinoderms