Thermal Processing via Air Frying Improves the Antioxidant Properties of Brassica Vegetables

Abstract

Brassica vegetables has demonstrated many health benefits over the years due to its composition of phenolic, flavonoid, and glucosinolate content. However, these bioactive molecules can be easily depleted during gastronomic operations. Therefore, a sustainable method which improves the phenolic content and antioxidant activity is required at large for the processors and consumers. Thermal processing has demonstrated as a method to improve the phenolic content and antioxidant status of Brassica vegetables. In the current study four different thermal processing methods, including freeze drying, sauteing, steam and air frying, were employed for five different Brassica vegetables, including kale, broccoli sprout, brussels sprout, red cabbage, and green cabbage. Total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activities were assessed using radical scavenging activity (DPPH and ABTS•+), reducing power (FRAP), and chelating ability of the metal ions. Among tested, air frying at 160oC for 10 minutes showed the highest TPC, TFC, and antioxidant activity of the Brassica vegetables, while sautéing showed the lowest. Steam treatment was preferred over the freeze-drying treatment. Within the vegetables tested, both kale and broccoli sprout contained higher antioxidants properties in most processing treatment employed. Results also indicated that there is a strong correlation between TPC, TFC, and the antioxidant activity (p<0.05). This study indicates that air frying could be a choice of sustainable thermal processing method for improving biomolecules for Brassica vegetables.

The effect of pH on the phenolic content and antioxidant properties of three different mustard extracts

“…Extraction of phenolic compounds from oilseeds, including mustard, has been carried out for many years using a wide variety of methods in which canolol has gained considerable attention lately. Canolol is a thermally generated phenolic compound that is not naturally present (Fadairo et al., 2022; Nandasiri, Fadairo, et al., 2023; Nandasiri, Semenko, et al., 2023). However, with the application of thermal treatments, canolol is formed via decarboxylation of sinapic acid (Nandasiri, Fadairo, et al., 2023; Nandasiri, Semenko, et al., 2023).…”

“…Canolol is a thermally generated phenolic compound that is not naturally present (Fadairo et al., 2022; Nandasiri, Fadairo, et al., 2023; Nandasiri, Semenko, et al., 2023). However, with the application of thermal treatments, canolol is formed via decarboxylation of sinapic acid (Nandasiri, Fadairo, et al., 2023; Nandasiri, Semenko, et al., 2023). Prolonged thermal treatments have been reported to have detrimental effects on the concentration of canolol as it undergoes dimerization (Nandasiri & Eskin, 2022; Nandasiri, Fadairo, et al., 2023; Nandasiri, Semenko, et al., 2023).…”

“…However, with the application of thermal treatments, canolol is formed via decarboxylation of sinapic acid (Nandasiri, Fadairo, et al., 2023; Nandasiri, Semenko, et al., 2023). Prolonged thermal treatments have been reported to have detrimental effects on the concentration of canolol as it undergoes dimerization (Nandasiri & Eskin, 2022; Nandasiri, Fadairo, et al., 2023; Nandasiri, Semenko, et al., 2023). The decrease in canolol when extracted at 180°C for 20 min could be due to its conversion to other forms (Aachary & Thiyam‐Hollander, 2012; Fadairo et al., 2021; Nandasiri et al., 2019; Nandasiri et al, 2021a, 2021b; Nandasiri & Eskin, 2021, 2022).…”