Comparative effect of cold and freezer storages on physicochemical and bioactive-related parameters of purple carrot ( Daucus carota L.)

Purple carrots are known by their health benefits, which are mainly attributed to their high content in anthocyanins. However, these compounds are often lost during the post-harvest period. In the present study, we compared the effects of refrigeration and freezing on quality and bioactive-related parameters, particularly anthocyanin content, of purple carrots during their storage for 4 weeks. For refrigeration, the storage time was additionally evaluated whereas the sample pre-treatment (whole or sliced) was in detail studied for freezing. In terms of quality, refrigeration at 4 °C for 2 or 4 weeks exhibited better results (i.e., 25% improvement in maturity index). Also, higher polyphenol content was obtained from refrigeration at 4 °C for 4 weeks (535 μg GAE/g DW versus 281 μg GAE/g DW in the fresh-control sample). Similar results were measured for anthocyanins (1,298 μg EC3G/g DW for refrigeration for 4 weeks versus 632 μg EC3G/g DW in fresh-control sample) and for antioxidant activity as DPPH (17.83 mg eq Trolox/g DW versus 11.41 mg eq Trolox/g DW in the control) and FRAP (27.05 versus 16.34 mg eq Trolox/g DW in the control). These results indicate that refrigeration at 4 °C enables physicochemical and bioactive-related properties of purple carrot to be better preserved than freezing.