Investigation of Naringin Content and Antioxidant Activity in 14 Citrus Fruit kinds in Response to Freezing Stress

In this study, fruits of 14 citrus varieties which damaged by freezing and 6 non damaged fruits which obtained from commercial trees were collected from germplasm collection of Citrus Research Institute. After initial evaluation, two main parts of fruit tissues were separated (peel and pulp) and after extraction procedures stored at -80 oC. Evaluating characteristics included number of seeds, peel thickness, TSS, TA, TSS/TA, total phenol, antiradical activity and amount of naringin. The results showed that the peel thickness had a positive and significant correlation with naringin content. Phenolic compounds of peel and pulp taken from non damaged fruits was higher than thus damaged fruits under freezing conditions. There were a significant correlation between peel and pulp Phenolics and antiradical activity. Naringin levels in both tissues were higher in frozen fruits than non damaged fruits. Unshiu which is known as a resistance variety to chilling injury had lower rate of naringin than other damaged fruits. Conclusion, naringin was a main compound in bitter fruits under freezing conditions, which is capable used in the processing industries.