Evaluation of potato germplasm for cold chipping ability and cold sweetening

A total of 907 potato germplasm accessions along with four processing varieties (two indigenous and two exotic) stored in the cold store at 2-4°C for 6 months were reconditioned for 7 days and evaluated for chip colour. None of the cultures produced acceptable chip colour (colour score up to 5). Fourteen accessions having chip colour score between 6-8 were further reconditioned for 21 days and re-evaluated for chip colour and certain processing related biochemical parameters. Two accessions, viz., Azul Soucco (Peru) and B 6561-4 (USA) produced acceptable chip colour of 4 and 5, with a dry matter content of 24.9 and 19.4% and reducing sugars content of 0.087 and 0.185% on fresh weight basis, respectively, as compared to the best control Frito Lay 1625 (score 7). The mean chip colour improved following reconditioning from 7 to 21 days, while a decline of 30 and 38% was observed in the mean contents of reducing sugars and free amino acids, respectively. Azul Soucco (Peru) was identified as the best accession for cold chipping and could be used for the development of indigenous cold chipping varieties. As regards, cold sweetening, except Dore (The Netherlands) and PSP 30-10 (Peru), the tubers of remaining 12 accessions and all the four processing varieties after 21 days of reconditioning contained lower levels of total sugars than the prescribed limit (>1.25% on fresh weight) which imparts sweet taste in table potatoes and can be used as parents for breeding table potato varieties with low or no sweetness.