Research aims to improve quality of Australian farmed seafood

A Southern Cross University marine science student is hoping to utilise Japanese expertise in fisheries to improve the quality of Australian farmed seafood.

Shiori Naka is completing a Master of Marine Science and Management with the University’s National Marine Science Centre in Coffs Harbour and has recently returned from the island of Kyushu in Japan where she attended the autumn meeting of the Japanese Society of Fisheries Science at Kyushu University Hakozaki campus.

Dr Jeff Guy, who is a co-supervisor from the University’s Marine Ecology Research Centre, said Ms Naka’s research was aimed at investigating methods such as ‘Ikijime’, that could maximise the freshness of farmed seafood.

“The Japanese are the world experts on seafood quality. This knowledge is built on decades of scientific research; however most of the literature is only published in Japanese and as a result many of the advances in methodology and species specific data remain lost to the English speaking world,” Dr Guy said.

“Ms Naka’s work is essentially to bridge this gap, modernise our methods while also building our understanding of seafood freshness in Australian farmed and wild species."

Ikijime is a method of killing fish which immediately stops any muscle movement, reducing the loss of the Adenosine triphosphate (ATP) in the muscle.

“Through this research we will gain a better understanding of how fresh farmed and wild caught fish are when they reach the plate. Ikijime is used by many recreational fishers, but not in commercial fishing or farming,” Dr Guy said.

Assisting Ms Naka in her laboratory work is Southern Cross Plant Science manager Ashley Dowell and Japanese scientist Dr Makoto Terayama of the Miyazaki Prefectural Fisheries Experimental Station.

“Our current method of determining ATP and its breakdown products in fish muscle is almost 30-years-old and this is now being examined and modified for a modern approach with the help of Japanese scientists,” Mr Dowell said.

Another outcome of the project is the determination of levels of ‘umami’, a Japanese word which can be translated as "pleasant savoury taste". Umami was first identified as a separate and distinct taste in 1908. The taste-active components are due to free glutamate and the nucleotides inosinate (IMP) and guanylate (GMP).

“It has been known in Japan for a long time that the initial sweet, meaty and species-characteristic flavours of fresh fish reflect the combination of IMP and free amino acids present in the flesh. Knowing when levels of IMP are at their highest in seafood will therefore ensure the best eating quality,” Ms Naka said.

Ms Naka’s principal supervisor is Dr Danny Bucher and co-supervisors include SCU researchers Professor Les Christidis, Dr Steve Provost and Sue Poole, Seafood Team Leader, Health and Food Sciences precinct, Brisbane.

The research has Animal Research Authority from the Southern Cross University Animal Care and Ethics Committee.

Photo: Shiori Naka at the National Marine Science Centre.