RESUMO
The method of ultrasound-assisted extraction (UAE) was utilized to extract polyphenols from Jerusalem artichokes tuber (JAT). To determine the ideal values for ultrasound power (UP), extraction time (ET), and temperature (TP), a response surface methodology was utilized. JAT extracts were prepared using UAE and their content of total flavonoids (TFC), total polyphenols (TPC), ferric reducing-antioxidant activity (FRAP), and 2, 2'-diphenyl-1-picrylhydrazyl (DPPH) were determined. Accordingly, optimal settings were obtained where TP = 80.0 °C, ET = 14.99 min, and UP = 99.2 °C. These conditions caused TPC, TFC, FRAP, and % DPPH values to reach 4163.6 mg GAE/kg, 2731.6 mg RE/kg, 2.16 mmol/L, and 85.2% respectively, with general-desirability values of 1.00. In addition, DPPH (R = 0.950) and FRAP (R = 0.962) correlated with TPC, indicating that TPC contributed significantly to antioxidant activity. It was found that UAE extraction yields were higher than conventional extraction yields.
RESUMO
The artichoke tuber is full of nutrients, inulin, and phytochemicals. It has been used to treat illnesses including diabetes and colon cancer, as well as in food product formulation, but limited information on the Jerusalem artichoke tuber (JAT) powder characterization exists in the literature, hence in this paper, JAT was freeze and oven-dried. It was powdered into JAT-freeze-dried-(FD)-powder and oven-dried (OD)-powder. This enabled the JAT powder's functional and physical properties to be studied. As a result, JAT powder's morphology, microstructure, and functional groups, as well as the powder foaming, swelling, solubility, antioxidant, color pasting, bulk, packed, and particle distribution properties were studied. Results indicated that the average particle distribution size at Dx90 and Dx80 displayed a distinct difference at p ≤ 0.05, while the bulk (0.39 g/cm-3) and packed (0.48 g/cm-3) densities recorded a lower value for FD powder. The FD powder's foaming capacity (24.0%) was significantly distinct (p ≤ 0.05) from the OD powder. Also, the solubility of FD powder was 6.2 g/g at 50 °C, and that of OD powder was recorded as 2.3 g/g. Again, the FD powder had a higher ABTS+ (34.3 mM (TE)/g dw) and CUPRAC (94.61 mM (TE)/g dw) capacity. Besides, a significant (p ≤ 0.05) dissimilarity among the powder color parameters (L∗, a∗, b∗, C∗, and whiteness) was observed. More so, the XRD and FT-IR characterization established a semi-crystalline or amorphous nature of the powder containing polysaccharides, and a broad halo pattern 2 θ at an angle 19.3° and 20 ° for FD powder and OD powder respectively. The FD powder particles were more agglomerated than those of OD powder. This was seen as a microscopic image, again FD powder revealed a higher pasting temperature and a drop in peak viscosity. Based on the results obtained, JAT (FD and OD) powder has all the quality attributes required of a powder for culinary product formulation.