Impact of drying and micronization on the physicochemical properties and antioxidant activities of celery stalk.

BACKGROUND

The influence of convective drying and ball-mill treatment of celery stalk on particle size distribution, physicochemical properties, bioactive compounds and antioxidant activities were analyzed in this study.

RESULTS

Ball-milling of celery stalk dried at temperatures of 50, 75 and 100 °C resulted in decreased average particle sizes of 48.8, 10.5 and 7.2 µm, respectively. Bulk density was increased with reduced particle size. Darker (L*) and reddish (a*) powders were formed at higher temperatures, while ball-milling increased greenness (-a*) of powders dried at 50 and 75 °C. Total content of phenol compounds increased with increasing temperature. 2,2-Diphenyl-1-picrylhydrazyl radical scavenging activity and reducing power were affected by ball-milling for 24 h and drying at elevated temperatures. Iron chelating ability was unaffected by increasing temperature or reduced particle size.

CONCLUSION

Increasing drying temperatures not only decreased the average particle size of powders, but also increasingly reduced particle size after ball-milling. Micronization of celery stalk dried at the highest temperature had the best antioxidant activities. Drying and ball-milling were not highly deleterious to the major phenolic structures. © 2017 Society of Chemical Industry.