Effects of ultrasonication, agitation and stirring extraction techniques on the physicochemical properties, health‐promoting phytochemicals and structure of cold‐brewed coffee

Ultrasonication, agitation and stirring or a combination of ultrasonication, agitation and stirring extraction techniques were applied to observe their effects on the physicochemical properties, health-promoting phytochemicals, and structure of cold brewed coffee. RESULTS All the extraction techniques led to significant (P < 0.05) increases in the color values, total soluble solids, antioxidant activities and most organic acids, while a combination of extraction techniques increased the chlorogenic acid and caffeine content significantly (P < 0.05) compared with that by conventional methods. Fourier transform infrared spectroscopy allowed us to identify the different compounds in the cold-brewed coffee extract rapidly. The partial least square regression model presented good predictability because experimental and predicted values were close to each other. Principal component analysis revealed that levels of all phytochemicals correlated with the use of non-conventional methods. CONCLUSION The combination of ultrasonication and agitation might be the best option to enhance the various phytochemicals in cold-brewed coffee. ? 2018 Society of Chemical Industry