Effects of Steeping Particle Size on the Chemical Composition, Antioxidant Activity, and Lipolysis Inhibitory Ability of Tea Infusions From Black Highland Barley Roasted at Different Temperatures.

Roasted barley is traditionally valued as a tea ingredient for its flavor and health-promoting benefits, which are governed by steeping and roasting conditions. This study investigated the effects of particle size (>4.0 mm (S0), 1.0-4.0 mm (S1), 0.5-1.0 mm (S2), 0.25-0.5 mm (S3), 0.125-0.25 mm (S4), and <0.125 mm (S5)) on the release patterns of constituents, as well as the antioxidant and lipolysis inhibitory properties of black highland barley (BHB) roasted at different temperatures (180-240°C) during tea infusion preparation. Results revealed that constituent leaching generally increased with decreasing steeping particle size, with β-glucan, free glucose, and polyphenols peaking at S4, but total sugar and protein at S5. The release levels of constituents during steeping were mainly governed by roasting temperature, with BHB roasted above 200°C significantly enhancing their contents in the tea infusions (p < 0.05), whereas roasting at 240°C resulted in decreases in β-glucan, protein, and free glucose. Consequently, the steeping cycle and color characteristics were shaped by the interactive effect of grinding and roasting. Relatively higher radical scavenging activities were observed in tea infusions at S4, with the highest rates found in those roasted at 240°C. However, tea infusions of BHB roasted at 200°C exhibited the strongest lipolysis inhibition. These results suggested that steeping at S4 was preferred for roasted black highland barley (RBHB) beverages, with functional benefits primarily determined by roasting temperature.