Effect of UV-C light on anthocyanin content and other quality parameters of pomegranate juice

Pomegranate juice (PJ) was subjected to UV-C irradiation as a non-thermal technology and changes in major quality characteristics of juice such as anthocyanins, polymeric colour, antioxidant activity and total phenol content were determined. The results were compared with control (untreated) and heat treated (at 90 degrees C, 2 min) juice samples. UV-C treatment preserved the major quality characteristics of pomegranate juice better than heating process. After UV-C treatment, total monomeric anthocyanin content of pomegranate juice did not change significantly and decrease in individual anthocyanin pigments were between 8.1% and 16.3%. However, anthocyanin content of PJ was significantly affected by heat treatment (P < 0.05) and 15.4% and 28.3% of individual anthocyanin pigments were lost after this process. Also, differences between the control and UV-C treated PJ samples were small in terms of polymeric colour values (P > 0.05) while polymeric colour of PJ were significantly affected by heat treatment (P < 0.05). There were no significant changes in antioxidant capacity evaluated by trolox equivalent antioxidant capacity (TEAC) assay and total phenol contents of PJ after UV-C and heat treatments. The effectiveness of the UV-C system on the aerobic plate count, yeast and mould count and Esherichia coli ATCC 25922 as a surrogate microorganism of E. cola O157:H7 in PJ resulted in 1.8, 1.45 and 6.15 log reductions, respectively. (C) 2011 Elsevier Inc. All rights reserved.