Effect of Tray Drying on Antioxidant, Total Phenols and Total Flavonoid Content of Red Skinned Onion

Sonia Morya, Arno Nuemann, Promila Godara, Sharvary Arun Vichare, Rajesh Venkata Vaddi, Sahithi Rajaboina, Varsha Kothapally, Tanushree Das, Yashdeep Rao, Ashar K Muhammed and Vinod Kumar


The onion holds significant importance as a key ingredient in nearly all types of dishes. Adding onions not only improves the taste, but also, they have some medicinal, anti-inflammatory, and anti-microbial characteristics. Various forms of dehydrated onions are available, such as flaked, minced, chopped, and powdered. These products hold considerable value and play a significant role in the worldwide trading arena. Moreover, the onion plant is extensively utilized as a flavoring element in a diverse range of food creations, including minced meats, sauces, soups, and salad dressings. Drying the plant material serves to lower the moisture content of the product to an appropriate level for storage, while also leading to the diminishment of flavor, taste, color, and nutritional elements. Mainly dried onions have the more content of flavonoids, phenols and antioxidants than fresh onions. There are many ways to dry the onions such as sun drying, microwave drying, tray drying. This study is aimed to assess the quantities of flavonoids, phenols, and antioxidant properties in tray dried onions. Slices of red onions underwent drying on a tray dryer set at 60 °C for a duration of 6 h. The present study proves the effect of during at 60 °C to reduce the moisture content to 11.50%. The assessment of antioxidant effectiveness was carried out using the DPPH assay, while quantification of overall phenolic and flavonoid contents was determined through the Folin-Ciocalteu (FC) and aluminum chloride methods, respectively. The findings indicated that the total carotenoid content and the total phenolic content were estimated at 0.11 g/100 g and 528.89 mgGAE/100 g respectively. The total concentration rose from 9.78 mg/100 g (control) to 159.56 mg/100 g capable of demonstrating 14.23% antioxidant potential. Further analysis from Fourier Transform Infrared (FTIR), colorimetry as well as the thermal degradation of the red onion showed that the concentration of total phenols, flavonoids, and antioxidants was highest at the temperature of 60 °C compared to other temperatures. These findings suggest that tray drying can be an effective method for enhancing the antioxidant properties of red onions.

Published on: November 15, 2023
doi: 10.17756/jfcn.2023-s1-081
Citation: Morya S, Nuemann A, Godara P, Vichare SA, Vaddi RV, et al. 2023. Effect of Tray Drying on Antioxidant, Total Phenols and Total Flavonoid Content of Red Skinned Onion. J Food Chem Nanotechnol 9(S1): S641-S646.