Comparative Evaluation of Ultrasonic and Water Bath Extraction on Bioactive Compounds, Phenolics, Fatty Acids, and Lipid Indices of Raw and Roasted Chia Seeds at Different Temperatures.

In this study, the effects of roasting and extraction conditions on the bioactive compounds, antioxidant capacity, fatty acid profile, and lipid quality of chia seed extracts were investigated. The oil content of roasted chia seeds ranged from 25.67% to 29.67% with ultrasonic extraction and from 23.82% to 26.00% with water bath extraction. Total phenolic content varied between 153.61 and 191.67 mg GAE/100 g for ultrasonic extraction and 154.26 and 186.06 mg GAE/100 g for water bath extraction. Total flavonoid content ranged from 48.50 to 64.88 mg/100 g and from 45.45 to 54.07 mg/100 g for ultrasonic and water bath extraction methods, respectively, indicating generally higher extraction efficiency with the ultrasonic method. Roasted chia seeds generally exhibited improved extractable bioactive compounds compared with the control. Both ultrasonic and water bath extraction increased oil yield and the concentrations of total phenolics and total flavonoids, with ultrasonic extraction consistently providing slightly higher values than the water bath. The highest oil yield was obtained by ultrasonic extraction at 40°C, whereas the greatest total phenolic content was achieved at 25°C for 20 min. Total flavonoid content also reached its maximum under ultrasonic extraction at 25°C for 40 min. In raw chia seeds extracted using the ultrasonic bath system, gallic acid and 3,4-dihydroxybenzoic acid contents ranged from 18.72 to 33.93 mg/100 g and 6.14 to 40.79 mg/100 g, respectively. In roasted chia seeds, catechin and caffeic acid contents ranged from 19.59 to 116.46 mg/100 g and 3.09 to 12.53 mg/100 g, respectively, with the highest values generally obtained at 40°C for 40 min. For individual phenolic compounds, ultrasonic extraction markedly increased gallic acid, 3,4-dihydroxybenzoic acid, catechin, and caffeic acid contents compared with the control. In general, longer extraction time (40 min) and, for some compounds, higher temperature (40°C) promoted greater phenolic recovery, with the highest catechin and caffeic acid concentrations observed at 40°C for 40 min. Linolenic acid content in oils extracted from roasted chia seeds ranged from 69.32% (control) to 69.71% (40°C/20 min) using ultrasonic extraction, and from 69.46% (25°C/40 min) to 69.81% (40°C/40 min) using water bath extraction. The fatty acid composition was only minimally affected by the extraction method or processing conditions. Linolenic acid remained the predominant fatty acid, with only slight variations among treatments, indicating that neither ultrasonic nor water bath extraction, nor the tested extraction temperature and time, substantially altered the lipid profile. Overall, extraction treatments produced higher values than the control, indicating that both extraction methods enhanced the recovery of these compounds, with ultrasonic extraction showing superior performance.