Characterization of onion (Allium cepa L.) by-products as food ingredients with antioxidant and antibrowing properties
Special Symposium - Innovations in Food Technology (LMC Congress)
Meals - Convenience, Gastronomy & Quality (Food-1b)
Keywords: onion by-products, total phenols, quercetin, antioxidant activity, antibrowning properties
Onion is the second most important world horticultural crop after tomatoes.
Onion is one of the major sources of dietary flavonoids in many countries and it has been shown to have beneficial effects on human health. They have been found to have effects on the cardiovascular system and in the prevention of cancer. More than 450,000 tonnes of onion waste is produced each year in Europe. Thus, there is a great disposal of onion wastes which could be processed and stabilized to obtain onion by-products.
Our objective was to evaluate onion by-products (juice, paste, bagasse) from two Spanish cultivars (`Recas´ and `Figueres´) stabilized by temperature (freezing, pasteurization and sterilization) in order to evaluate their potential use for the food industry as natural food ingredients: sources of antioxidants, antibrowning or bioactive compounds.
Total phenols were determined spectrophotometrically and quercetin was determined by HPLC. The antioxidant activity was evaluated by the measurement of the DPPH• radical scavenging. The inhibition of the polyphenoloxidase (PPO) activity was measured spectrophotometrically in avocado extracts.
Onion by-products were supplied by an onion industry in Catalonia (Spain) and their stabilization was held in the CNTA (Food Technology National Center) in La Rioja (Spain).
Our results showed that `Recas´ cultivar, paste onion by-product and pasteurization stabilization technique offered significantly (p < 0.05) higher content of total phenols and quercetin. Analysing the radical scavenging and PPO inhibition parameters measured, the pasteurized `Recas´ paste also offered the best antioxidant and antibrowning characteristics.
It can be inferred that processing Spanish `Recas´ onions to obtain paste by-products and stabilizing them by a mild treatment, such as pasteurization, could represent a useful alternative to food industry that add a new value to onion wastes.
Presented Wednesday 19, 17:10 to 17:15, in session Meals - Convenience, Gastronomy & Quality (Food-1b).
