Treat Obesity and Diabetes with Wasted Red Onion Peel


Treat Obesity and Diabetes with Wasted Red Onion Peel

Glucose intolerance can lead to type II diabetes, which is very prevalent along with obesity. Obesity if left unaddressed can lead to complications like diabetes and hypertension. Since Onions are a common food in many regions of the world and their peel goes into waste, so Red Onion Peel Extracts (ROPE) were studied for their effects on obesity and blood sugar levels in Egypt, which showed promising results.

Red onions are native to and highly consumed vegetable crops in Egypt. The plant is found well distributed in the temperate regions. This vegetable has been used for years to treat stomach ulcers, hypertension, and fever due to infections like malaria. The onion peels get wasted in the market during trading and selling, also the peels get wasted by the food industry. There should be a proper way to take advantage of the many benefits these peels have to offer. The peel of onions is abundant in organosulfur, anthocyanin, flavonoids, quercetin, kaempferol, and polyphenols. Some flavonoids like polyhydroxyphenols (Tannin) have been identified in the inner layers of red onion peels. These tannins have a known antioxidant effect. Since onion skin has been so dense in nutrients, it can become a functional ingredient if its antioxidant activity is well studied.

Due to the presence of flavonoids, the onion’s skin becomes a strong antioxidant. Especially Red onion peel (ROP) has a good reservoir of antioxidant, antimicrobial, and anti-cancerous properties, thereby reducing the risk of cardiovascular and oncological diseases.ROP is different from yellow onion due to the presence of Anthocyanins (the most biologically potent antioxidant). Nanotechnology has transformed many fields including food sciences.

A group of researchers tried to extract bioactive compounds in wasted EgyptianROPs and used nanotechnology for the preparation of Nano-capsules in an attempt to use them as a functional or supplemental food against obesity and blood sugar.

For extraction of bioactive compounds, ROP was collected from the local market, from which ethanols and water was extracted and ROPEE (Red Onion Peel Ethanol Extract) was encapsulated using natural polymers separately like chitosan, sodium alginate, and gelatin by nanotechnology. The total phenolics, flavonoids content, and antioxidant activity were also observed. In rats, the oral glucose tolerance test was observed against ROPEE.

The result showed that the total phenolics and flavonoids content was higher in ROPEE than ROPWE (Red Onion Peel Water Extract), and after micro-encapsulation and nano-emulsions, the best efficiency was of sodium alginate of ROPEE. Similarly, ROPEE showed better antioxidant activity than ROPWE. After using Scanning Electron Microscopy for studying physical characteristics of ROPE and sodium alginate forms, they found that the nano-emulsification process protects the extract against heat by elevating its heat resistance potential, making red onion peel extract nano-emulsion fit for use in the bakery products as its antioxidant potential will prevail under high temperature. The cake made from these proved to be beneficial in lowering blood sugar levels and for weight reduction in rats.


Red Onion Peels, antioxidants, anthocyanins, flavonoids, tannin, nano-capsules, nanotechnology, diabetes, hypertension, sodium alginate, nano-emulsification