Improvement of the Ultrasound-Assisted Extraction of Polyphenols from Welsh Onion (Allium fistulosum) Leaves Using Response Surface Methodology

Abstract

Welsh onion (Allium fistulosum) leaves contain several bioactive compounds that can be extracted and used to develop new value-added products (e.g., functional foods and dietary supplements). In the current work, optimal ultrasound-assisted extraction (UAE) conditions to obtain extracts with high polyphenols content and DPPH (1,1-diphenyl-2-picrylhydrazil) scavenging activity were identified using response surface methodology. A complete 3k factorial design was used to evaluate the effect of different variables of the UAE (extraction temperature, time, and ethanol concentration) on the polyphenols content and the DPPH scavenging activity of the extracts. The best conditions for UAE to reach both the highest values of total polyphenols content (51.78 mg GAE/100 g) and DPPH scavenging activity (34.07 mg Trolox equivalents/100 g) were an extraction temperature of 60 °C, time of 10 min, and ethanol concentration of 70% v/v. The antioxidant activity of the extracts obtained at the optimal conditions was also evaluated by 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) and ferric reducing antioxidant power (FRAP) assays obtaining values of 155.51 ± 2.80 μM Trolox/100 g and 1300.21 ± 65.55 μM Trolox/100 g, respectively. Moreover, these extracts were characterized by UHPLC-ESI+-Orbitrap-MS analysis finding that cyanidin (6.0 mg/kg) was the phenolic compound found in the highest amount followed by quercetin-3-glucoside (4.4 mg/kg).

Optimization of microwave-assisted extraction of antioxidant compounds from spring onion leaves using Box–Behnken design

“…Recently, optimal conditions for ultrasound-assisted extraction (UAE) have been identified to obtain extracts from Welsh onion leaves. These extracts exhibit high polyphenol content and 2,2-Diphenyl-1-picrylhydrazyl (DPPH) scavenging activity 31 . UAE technique has gained popularity due to its ability to reduce solvent consumption, shorten extraction time, and improve extraction yields.…”

Establishment of a Sonotrode Ultrasound-Assisted Extraction of Phenolic Compounds from Apple Pomace

“…Although there is little research about the use of ultrasound technology for extracting phenolic compounds [ 27 , 28 ], it has been applied previously to apple pomace with other aims such as isolating xyloglucans [ 29 ], or extracting pectin [ 30 ]. Further, ultrasound technology for optimizing the extraction of bioactive compounds has been performed by other authors in other matrices such as eggplant [ 31 ], orange peel [ 32 ], tangerine [ 33 ], cashew apple bagasse [ 34 ] or onion leaves [ 35 ].…”

Green Onion (Allium fistulosum): An Aromatic Vegetable Crop Esteemed for Food, Nutritional and Therapeutic Significance

“…These vitamins are vital for energy metabolism, nervous system function, DNA synthesis and overall human well-being [45]. Vitamin A in green onions is primarily present in the form of beta-carotene, a precursor to active vitamin A [48], which, as a component of the light-absorbing molecule in the eye's retina, plays a critical role in maintaining healthy vision [45]. Vitamin A is also essential for cellular differentiation, gene expression, growth, healthy skin, healthy immune system function, bone development and reproduction [49].…”

“…Plants play a crucial role in providing essential minerals necessary for maintaining a healthy human body [2]. A variety of vegetables and fruits serve as abundant sources of major minerals like potassium and calcium, both of which are integral to various physiological functions [48]. Green onions, like many other fresh vegetables, are noted for their rich source of these vital minerals, including potassium, magnesium, phosphorus and calcium, making them a valuable addition to a balanced diet [68].…”

“…Calcium, on the other hand, is crucial for bone health, blood clotting and muscle function. Both of these minerals are integral to maintaining overall health, and green onions contribute to meeting the body's requirements for these minerals [48]. Incorporating green onions into one's diet not only adds flavor and nutrition but also helps ensure an adequate intake of essential minerals, further emphasizing the importance of including a variety of plant-based foods to support human health and well-being.…”