Respiratory activity and phenolic compounds in pre-cut celery

The effect of temperature on respiratory activity and total phenol and flavonoid contents in pre-cut celery was assessed within the 24 h following this minimal processing. To this end, celery petioles were cut as strips, conditioned in crystal polyethylene tereplithalate trays covered with PVC film and stored at 0, 10 and 20 degrees C. Samples were removed at 0, 2, 4, 6 and 24 h after processing to analyse respiratory activity and concentrations of total phenols and flavones. For the samples kept at 0 degrees C for 24 h, chlorogenic acid was also determined, along with total flavonoids and antioxidant power. At this temperature, the total phenol contents remained basically constant, though at 10 degrees C it increased considerably two hours after applying the cutting stress. At 20 degrees C the increase observed was less important. The flavones, identified by HPLC in pre-cut celery were apigenin and luteolin, whose concentrations also increased between two to six hours after processing. However, exposure for 24 h at 0 degrees C produced a considerable decrease in total flavonoids. (c) 2006 Elsevier Ltd. All rights reserved.