Emerging science: onion skins a salmon preserver? By Jerome Smail Onion skins could be effective in extending the shelf life of fresh fish, researchers at the University of Florida have found.
Senem Guner led a team of scientists from the university s Institute of Food and Agricultural Sciences (UF/IFAS) focusing on the preservation of salmon.
First, the researchers extracted bioactive antioxidant compounds – anthocyanins and polyphenols – from onion skins by keeping them in hot water for around 80 minutes and then filtering the skin.
The skin and flesh of red and yellow onions were extracted with water mixed with ethanol and acetone at 25°C, 45°C, 65°C and 90°C. Anthocyanin and polyphenol levels and antioxidant capacity were determined after extraction. Then extract was then spread over the salmon.
Onion skins may offer a way to reduce food waste and keep fish fresh.
Fresh salmon is good for about two days on the market shelf because it is a fatty fish. In the study, untreated minced salmon started to spoil after the first day because mincing increases the rate of oxidation. The best package application in the experiment increased this period to almost 10 days.
“For fish, freshness is not only about taste,” says Senem Guner, a former doctoral student in the University of Florida/Institute of Food and Agricultural Sciences College of Agricultural and Life Sciences.
“If the fish is going bad, foul odors, color, and even taste warn us not to consume it. If we minimize the risk from the beginning, we can produce healthier and safer food as well.”