Extracts from the fungi would extend shelf-life by up to six days during cold storage, compared to un-treated meat, according to results published in the Journal of Food Science.
And since oxidative spoilage of the fish is linked to colour, the extract was associated with improved colour stability of the meat, report the researchers from the Tokyo University of Marine Science and Technology.
Riding the ‘natural’ wave
Oxidation processes in food can lead to organoleptic deterioration in taste, colour and texture. And fish products are particularly susceptible to oxidation processes because of the high unsaturated lipid content.
The food industry has long been aware of this, and is increasingly seeking natural solutions rather than artificial additives, such as like butylhydroxyanisole (BHA) and butylhydroxytoluene (BHT), to extend the shelf life of milder-tasting products.
According to a 2003 report by Frost and Sullivan, the synthetic antioxidant market is in decline, while natural antioxidants, such as herb extracts, tocopherols (vitamin E) and ascorbates (vitamin C) are growing, pushed by consumer desire acceptance and easier market access.
The study builds on an earlier report from the same researchers published in the Journal of Agricultural and Food Chemistry. On that occasion, they reported that extracts from the same mushroom could prevent browning of tuna and beef meat when the mushroom extract was used as an additive.
New data
The researchers, led by Huynh Bao, formulated four preparations of the minced tuna meat, containing 0, 1, 3, or 5 millilitres of mushroom extract per 100 grams of meat. A dose-dependent response was observed, with the tuna meat’s shelf-life under ice storage being increased by 2, 4, and 6 days, respectively, compared to the meat without the extract.
Furthermore, five millilitres of the mushroom extract was found to be more effective than addition of a vitamin C salt at a level of 500 ppm or vitamin E at the same levels.
Beneficial effects on the colour of the meat were also identified, and linked to the level of lipid oxidation and the formation of metmyoglobin in the fish meat.
“F. velutipes, a traditional edible mushroom, has been used as a culinary vegetable without any known toxic effects,” wrote the researchers.
“This study clearly showed that the hydrophilic extract prepared from F. velutipes is a promising source of natural antioxidants for food and food stuffs,” they added.
Commenting on the formulation quantities, the researchers did add that at a dose of five millilitres per 100 grams of meat, this would scale up to 50 millilitres, prepared from 500 grams of mushroom, would be needed for one kilogram of meat.
“This amount of the extract seems not small for further practical application in the food industry,” they stated. “We have already found similar suppressing effects of a
hydrophilic extract prepared from the mushroom cultured media which has been mainly discarded or merely used as fertilizer of low-cost performance so far.
“The value-added utilization of the waste cultured media of F. velutipes for the preparation of functional extract would be more valuable than the use of edible fruiting body in terms of not only economic aspects but also environment-friendly resolution of the industrial waste treatment,” wrote Bao and co-workers.
Source: Journal of Food Science Published online ahead of print, Early View, doi:10.1111/j.1750-3841.2009.01069.x“Antioxidative Activities of Mushroom (Flammulina velutipes) Extract Added to Bigeye Tuna Meat: Dose-Dependent Efficacy and Comparison with Other Biological Antioxidants”Authors: H.N.D. Bao, H. Ushio, T. Ohshima