Extended harvest time improves the shelf life of celeriac (Apium graveolens var. rapaceum) through postharvest treatment and storage conditions

The purpose of this study was to examine the effect of harvest time (November or January) and postharvest treatments (hot water, H₂O₂, NaOCl and non-washed NDASH control) of celeriac (Apium graveolens var. rapaceum 'Mentor') on the changes in different storage conditions S-1 (0°C; >95% RH) or S-2 (0-5°C; 85-92% RH) during 180 or 120 days of storage period (SP). At the end of SP the percentage water loss ranged from 4.93% (from second harvest inside the S-1 with NaOCl treatment) to 39.29% (from first harvest in S-2 in control-unwashed root). The dry matter (DM) values (10.60-12.40%) increased gradually during cold storage up to 49.41% (in S-2 at first harvest with NaOCl treatment). During SP, total sugar content (1.74-3.03%) increased more in S-2 cooling room. Sucrose is the predominant sugar in celeriac roots (1.67-2.67%). Content of glucose (0.05-0.15%) and fructose (0.03-0.09) is much smaller. Depend on storage condition and postharvest treatment, glucose and fructose concentrations also increased significantly during SP but to a much lower level than sucrose. Nitrate levels at harvest time ranged from 430 to 675 mg kg^-1 fresh weight (FW). Storage condition (S-2) and stage of maturity (first harvest) resulted in nitrate accumulation up to 882.3 mg kg^-1 FW. Nitrate content in celeriac roots increased with prolonged storage in both storage rooms and all treatments. Storage at cold room (S-1) after different washing treatments is a practical strategy for reducing loss and maintenance quality in the celeriac during prolonged storage.