Carbohydrate changes in parsnip (Pastinaca sativa L.) during long-term cold storage

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 – control) of parsnip roots (Pastinaca sativa ‘Banatski dugi’ – old domestic cultivar) and effects on the quantitative and qualitative changes during different storage conditions (S-1 0±1°C; >95% RH or S-2 0-5°C; 85-92% RH). Water loss and quality changes in parsnip taproot were monitored after 60, 120 and 180 days of storage. At the end of storage the percentage water loss ranged from 4.71% (from second harvest inside the S-1 unwashed-control roots) to 26.0% (second harvest in S-2 with H2O2 treatment). Dry matter (DM) values varied from year and harvest time (21.36-23.83%). The DM content of parsnip roots increased gradually during cold storage up to 33.3% (in S-2 with hot water treatment). This increase in DM was followed by a significant (P£0.05) increase towards the end of cold storage, indicating water loss. Total sugar content is highly dependent on year and harvest time (9.57-10.69%). During storage, sugar content increased more in S-2 cooling room. Reducing sugar to non-reducing sugar (R/NR) ratio was around 1:10 and showed an increasing trend during storage. Sucrose is the predominant sugar in parsnip roots (8.51-10.05%). Content of glucose (0.35-0.40%) and fructose (0.10-0.33%) is much smaller. Depending on storage condition and postharvest treatment, glucose and fructose concentrations also increased significantly during cold storage, but to a much lower level than sucrose. Starch concentrations (4.50-5.43% at harvest time) during first month in cold storage declined to <10% of their initial level. The total conversion of starch into sucrose occurs after the second month of storage and starch level almost completely depleted (0.04%). Accumulation of sucrose may raise the culinary quality of cold-stored parsnip.