The effect of oven drying on bioactive compounds, antioxidant activity, and phenolic compounds of white and red‐skinned onion slices

Abstract

Moisture amounts of the white and red onions of the control group were determined to be 91.59% and 87.32%, respectively. The highest decrease in moisture content occurred within the red onion (7.14%) dried at 90°C. The total phenolic, total flavonoid contents, and antioxidant activity values of the white and red onions dried at both temperatures increased significantly compared to the control groups. The highest increase for total phenolic and total flavonoid contents were established for white and red onions dried at 90°C. Caffeic acid, rutin‐trihydrate, p‐coumaric acid, trans‐ferulic acid, apigenin‐7‐glucoside, quercetin, and trans‐cinnamic acid contents of both the undried and dried red onions were found to be higher compared to the contents of the undried and dried white onions. Additionally, the amounts of phenolic constituents of white and red onions dried at 50 and 90°C temperatures were higher compared to those of the control groups. Practical applications Various types of dried onions forms include flaked onion, minced onion, chopped onion, and powdered onion, and are a product of substantial prominence and importance across the global trade landscape. Moreover, the onion plant enjoys widespread use as a flavor additive in copious amounts of food formulations including comminuted meats, sauces, soups, and salad dressings. By drying the plant materials, the moisture content of the product is brought to a suitable value for storage, and in addition to this, it is to prevent the losses in the flavor, taste, color, and nutrients of the vegetable materials.

Dehydrated at Different Conditions and Powdered Leek as a Concentrate of Biologically Active Substances: Antioxidant Activity and Phenolic Compound Profile

“…The lowest AA found in WH and GR samples dried at 60 °C might have probably resulted from the longer DT during FD. Additionally, other authors found that both drying temperature and drying time are the crucial factors that influence the antioxidant activity of leek [ 13 ] and other vegetables [ 55 , 56 ]. FD is considered to be one of the best but most expensive methods of food dehydration.…”

Recent Advances in Bioactive Compounds, Health Functions, and Safety Concerns of Onion (Allium cepa L.)

“…The influences of food processing on antioxidant capacities of onions were investigated as well, including drying (143,144), freezing (145), heating (41, 145), sautéing (38), and high-pressure processing (36). For instance, heating and freezing were found to reduce antioxidant activity of onion ( 145), while sautéing did not significantly change it (38).…”

Nutrients and antioxidant properties of red, yellow and white onions (Allium cepa L) in Ibadan, Oyo State, Nigeria

“…This study recorded a quercetin content of 0.19±0.01 to 0.32 ±0.02. This varies with the result of Salamatullah et al(30) that recorded a quercetin content ranging from 0.89 ± 0.18 to 1.09 ± 0.06 in the control (un-dried) group, whereas they recorded the highest quercetin content in red onions oven-dried at 50 0 C. It also varies with the work of Jung-Ho et al(31) who recorded total quercetin glycosides varying from 16.10 to 103.93 mg/g DW extensively among three varieties of onions. Interestingly, Majid et al(29) found out in their research that sprouted onion powders contained more phytochemicals than raw onion powder which can be of importance in product development.…”