New Scientific Breakthrough: Key Technologies for Meat Quality Improvement and Freeze‑Thaw Preservation of Freshwater Drum

Freshwater drum (Aplodinotus grunniens), also known as freshwater large yellow croaker, is an emerging freshwater aquaculture species with great market potential. It features no intermuscular bones and fast growth rate. The Innovative Team for Breeding and Cultivation of Yangtze‑Endemic Aquatic Organisms at the Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, has carried out joint research with Jiangsu Haorun Biological Industry Group Co., Ltd. Focusing on two major pain points — muscle quality regulation and quality retention during frozen processing, the team has completed a series of studies. Relevant findings have been published in international journals, offering technical support for the industrial‑scale processing of this fish.

Salinity Temporary Rearing: An On‑farm Strategy to Enhance Umami Taste

Salinity acts as a critical environmental factor affecting fish metabolism and muscle quality. Through salinity‑gradient temporary rearing trials, the research team systematically investigated how different salinity levels and rearing durations alter the flesh quality of freshwater drum.

Studies confirm that temporary rearing under appropriate salinity conditions promotes the accumulation of umami amino acids and flavour‑active nucleotides in fish muscle, which directly improves flavour profiles. This technique can be applied in the late aquaculture phase without reformulating feed, providing a practical solution for enhancing seafood flavour at the farming end.

Salting Pretreatment Mitigates Quality Deterioration upon Freezing‑Thawing

Frozen storage is the mainstream logistics approach for aquatic products. Nevertheless, ice crystals formed during freeze‑thaw cycles may rupture muscle cells, trigger protein denaturation, degrade texture and cause juice loss, limiting the product quality of processed freshwater drum.

The team unravelled the protective mechanism of salting pretreatment: salting reduces mechanical damage inflicted by ice crystals on muscle cells and myofibrillar networks, and inhibits freezing‑induced protein denaturation. Consequently, the textural quality of thawed fish is improved. This addresses quality decay in frozen processing and facilitates the development of prepared aquatic food products.

Multiple Papers Published in International Journals with Multi‑project Funding

Three high‑quality research papers have been released in Antioxidants, Foods and Fishes respectively:

1. Effect of different salinities on the biochemical properties and meat quality of adult freshwater drum (Aplodinotus grunniens) during temporary rearing (Antioxidants)

2. Impact of pickling pretreatment on the meat quality of frozen‑thawed freshwater drum (Aplodinotus grunniens) (Foods)

3. Rearing time‑salinity synergy in osmoregulation: Ionic homeostasis and textural enhancement in adult freshwater drums (Aplodinotus grunniens) (Fishes)

The research received financial support from the Basic Scientific Research Operating Expenses of the Chinese Academy of Fishery Sciences, Jiangsu Provincial Independent Innovation Fund for Agricultural Science and Technology, Science and Technology Innovation Teams of CAFS, and the Key Technology Research on Artificial Breeding of Freshwater Large Yellow Croaker, among other programs.

Industrial Implications

Covering flavour regulation in aquaculture and quality protection for frozen processing, this set of findings forms a complete technical chain spanning late‑stage farming to frozen processing. On one hand, temporary salinity rearing helps raise the commercial value of live fish. On the other hand, salting pretreatment upgrades the quality of frozen prepared products. These advances support further deep‑processing and ready‑to‑cook product development for freshwater drum and accelerate industrialisation of this emerging aquaculture species.