Indian J. Plant Physiol., 2003 (Special Issue) pp. 489-494 PROCESSING QUALITY AND CIPC RESIDUES IN POTATOES STORED AT lO-12°C IN COMMERCIAL COLD STORES APPLYING CIPC R. EZ EKIEL 1 ' , BRAJESH SINGW, DINESH KUMAR2AND VIj AY PAUV " 'Cen tral Potato Research Institute, Shimla- 17100I, H.P. 2Central Potato Research Institute Camp us, Modipuraf!l-250 110, V.P. SUMMARY Potatoes stored at 10-12°C and 85-95 % llH in commercial cold stores at five cities in northern and central India were analysed periodically for processing quality and I sopropyl N-(3-chlorophenyl) carbamate (CIPC) residue levels. Tubers stored at 10-12°C produced chips of acceptable colour as compared to dark coloured, unacceptable chips produced by tubers stored at 2-4°C. The lighter chip colour could be related to lower level of reducing sugars. Cultivar Kufri Bahar accumulated excessive reducing sugars resulting in d ark colour chips. Tuber s of culti vars Kufri Jyoti and Kufri Lau vkar , produced and stored at Indor e and Ujjain respecti vely were found to be suitable for processing. CI PC re sidue levels va rl- d con siderabl y and th e maximum CIPC residue level observed in peel ranged from 0.2 to 16.1 mg/kg fw and in unpeeled tubers, it ranged from 0.03 to 2.7 mg/kg fw. This is within the acceptable limit of 30 mg/kg tuber. Key words: CIPC residue, potato, processing quality, storage INTRODUCTION level does not exceed the recommended maximum limit. The'aim of this study was to determine the effect of CIPC CIPC (Isopropyl N-(3-chlorophenyl) carbamate) also on the processing quality of pot atoes and residue known as chlorpropham is used for sprout inhibition in concentrations of CIPC in potatoes, stored in com mercial stored potatoes meant for processing and table purposes cold stores at 10- 12°C . in many countries (Kleinkopf et al. 1997). The advantage of this sprout suppressant on potatoes is that it is cost MATERIALS AND METHODS effective and can be used as post-harvest application unlike sprout suppressants like Maleic Hydrazide which Processing quality of potatoes and CIPC residue levels is used as a pre-harvest spray. CIPC was registered for were monitored in commercial cold stores located at five use in India as a sprout suppressant on potatoes only in cities in three states in northern and central India, during 1998 and therefore, its effect on the storage behaviour of 200 1. The details of the cold stores are given in Table 1. Indian potato varieties is not well documented. Small In these cold stores, well-cured potatoes were stored scale studies have been done under non-refrigerated at 1O-12°C and 85-95% RH. CIPC was applied twice on storage using dust formul ation of CIPC (Singh and Kaul the dates given above. CIPC was applied as a thermal 1999) but large scale storage studies using aerosol aerosol (fog) through an inlet fixed at about 3 feet above formul ation for fogging potatoes in large commercia l cold the ground level. A fogger (Dyna fog, USA) was used stores have not been carried out in India so far. CIPC for CIPC application and the dose applied was 35 ml residue analysis is necessary to make sure that the residue (50% a.i.) of a commercial preparation of CIPC called "O orja" manufactur ed by United Phosphorus Ltd., *Corresponding author; e-mail: rezekiel@cpri.hp.nic.in **Present address: Division of Plant Physiology, IARI, New Delhi- Mumbai. After application, the stores were closed for 48 110012 hours to allow CIPC aeroso l to settle on the potatoes and Indian J. Plant Physiol. , 2003 (Special Issue) pp. 489-494 489