Mushroom extracts keep fish fresher and pinker
Scientists in Japan have discovered that supplementing the diet of salmonids with mushroom extracts can stabilise the pink pigment astaxanthin during post-harvest storage at low temperatures.
The researchers at Tokyo University of Marine Science and Technology also found that using ergothioneine-rich mushroom extracts (ME) had a positive effect on the prevention of lipid oxidation.
Quality losses, production of unpalatable flavour and odour, shortening of shelf life, losses of nutritional values and possible production of unhealthy molecules are among the consequences of lipid oxidation.
The in vivo study was carried out on coho salmon (Oncorhynchus kisutch), which were fed a diet supplemented with ME of the fungus Pleurotus cornucopiae at different concentrations (0, 1 and 5 per cent) for two months. After euthanasia, muscle samples were obtained and stored at temperatures ranging from -2 to -18 ° C for four weeks.
Rainbow trout
The researchers also carried out an in vitro study in which ME of Flammulina velutipes was added to chopped rainbow trout (Oncorhynchus mykiss) fillets in concentrations of 0, 3 and 5 per cent, and then stored at -10 ° C for four weeks.
The in vivo investigation showed a significant increase in the weight of the fish at the end of the two months, without adverse effects on growth or pigmentation. At the end of the four-week storage period for both experiments, the groups treated with the different ME concentrations had lower lipid oxidation values ??and higher astaxanthin levels in the muscle samples, compared to the levels of the control groups.
The in vitro study also showed that the higher levels of astaxanthin retained in the muscle are directly related to a lower loss of natural colour.
The study concluded that the addition of ergothioneine from MEs successfully controlled lipid oxidation and stabilised astaxanthin during post-harvest storage at low temperatures.
