Effect of low‐temperature storage, gamma irradiation and iso‐propyl‐N‐(3‐chlorophenyl carbamate) treatment on the processing quality of potatoes

In Taiwan commercial storage of potatoes (CV Kennebec, Wu‐Foon, Cardinal) at 2°C. 85% RH, can supply the fresh market all year round. However, reducing sugar and total sugar which accumulate in the tubers will reduce the processing quality of potatoes. Reconditioning of tubers from cold stores was undertaken at ambient temperature (20°C) for up to 6 weeks. The optimum temperature for Kennebec and Cardinal reconditioning ranged from 20 to 25°C. However, after storage at 2°C for a long period, the sugar content of potato tubers cannot be reduced to a satisfactory level. When newly harvested potatoes were pretreated with CIPC (300–500 μg litre −1 ) and stored at 10°C, 80 % RH, sprouting was inhibited effectively. The quality of potatoes was retained well and reducing sugar remained at a low level for up to 8 months. MENA was found to be ineffective. Gamma irradiation of potatoes at 0.175‐0 20·0‐10–0.125 and 0.125 kGy for Cardinal, Kennebec and Wu‐Foon respectively was found to be effective in controlling the sprouting of tubers stored at 10°C, 80 % RH, for 9 months. A rapid increase in sugar content was found in irradiated Cardinal and Wu‐Foon after storage for 7 months, while the reducing sugar in irradiated Kennebec was still below 0°2 % after 8 month's storage. Gamma irradiation had no adverse effect on the ascorbic acid content, and higher firmness retention was obtained in irradiated tubers throughout storage at 10°C.