Cluster analysis of antioxidant compounds in dates (Phoenix dactylifera): Effect of long-term cold storage

Both soft (SD, Bam) and dry (DD, Kharak) date varieties were stored at 4 °C for six months followed by an additional one week storage at 18 °C. Antioxidant compounds (total phenolic content (TPC) and total flavonoid content (TFC)) of the dates increased following storage. Cluster analysis applied on TPC and TFC data before and after storage obtained two statistically significant clusters of SD and DD indicating that TPC and TFC had different behaviors according to the types of dates. As antioxidant concentration in dates was dependent on type of dates, selection of variety with high antioxidant compounds may be recommended. Further cold storage of up to six months followed by one week storage at 18 °C may further improve the level of antioxidant compounds.